Palm tree root system

Our 2010 blog entry by James Urban, FASLA, on the topic of how deep tree roots grow is consistently one of our most popular. Obviously there is a curiosity about this topic and a need for useful data about it. But the original post is a little technical and not as image-heavy as we’d like. So today we’re bringing you a new and improved version of the original post, with additional pictures and more simplified explanation of the factors that really influence how deep tree roots grow.

How deep tree roots grow depends on three simple factors. To answer this question I contacted Jim Urban, FASLA, a noted tree and soil expert. He contributed to the following post.

Roots require three things: water, oxygen, and soil compaction levels low enough (or with void spaces sufficiently large enough) to allow root penetration. If all these conditions are met, roots can grow to great depths. Under ideal soil and moisture conditions, roots have been observed to grow to more than 20 feet (6 meters) deep.

Early studies of tree roots from the 1930s, often working in easy-to-dig loess soils, presented an image of trees with deep roots and root architecture that mimicked the structure of the top of the tree. The idea of a deeply-rooted tree became embedded as the typical root system for all trees. Later work on urban trees that were planted in more compacted soils more often found very shallow, horizontal root systems. Urban foresters have successfully spent a lot of energy trying to make people understand that tree roots have a basically horizontal orientation, to the point that even many tree professionals now believe that deep roots in trees are a myth. The truth lies somewhere in between deep roots and shallow roots.

This totally horizontal root system formed on top of poorly drained soils. Photo courtesy of Miles Barnard.

Simply put, by Jim: “Trees are genetically capable of growing deep roots, but root architecture is strongly influenced by soil and climate conditions.”

The most typical limitations to tree rooting in urban areas are soil compaction and poor drainage. These are often related, with a compaction layer creating a poorly-draining hard pan. This results in a perched water layer that restricts roots. Hard pans and perched water tables can also be found in nature. In fine-grained clay soils and fine-grained silty soils, pore space — and therefore and rooting depth — is often limited. Since these conditions are quite common in urban areas, shallow rooted trees are often seen as “typical.”

Six foot long sinker or striker roots in well-draining soils. Note the remnant of horizontal roots at the trunk flare. Photo courtesy of Miles Barnard.

Orjan Stahl, a tree researcher in Stockholm, made an exhaustive study of over 500 trees that had root and utility conflicts. He regularly found roots at depths of 7 to 9 feet (2.1 to 2.7 meters) and the deepest root he encountered was at 23 feet (7 meters). In their 1991 paper, “On The Maximum Extent of Tree Roots,” E.L. Stone and P.J. Kalicz summarized previous root depth studies of 49 genera and 211 species growing in a wide variety of soil types. They found numerous examples of trees reported to be growing roots to over 33 feet (10 meters), and one report of a tree that grew roots to a depth of 174 feet (53 meters). Clearly, a tree’s ability to grow deep roots is not a significantly limiting factor in soil design.

4 foot deep rooting in loam soil that was on top of a hard pan. Photo courtesy of James Urban.

Given all this, and the unpredictable site constraints of the urban environment, urban trees need flexible solutions that can enable roots to grow out or down. In some sites, increasing soil depth is not a problem, while expanding may be limited by other constraints. The opposite can also be true. This is why the Silva Cell system is flexible in all three dimensions to respond to different spatial limitations.

These roots go at least 4 feet deep. This tree fell over after the irrigation contractor installed a line on the up wind side. Photo courtesy of James Urban.

The designed maximum depth of the system is 45 inches (1150mm). This is a strategic compromise between the system’s structural requirements, soil volume, and cost and constructability issues. The Silva Cell was designed to provide a deep soil volume because roots will grow to these depths. For urban sites where deep excavation is limited, one- or two-layer systems can provide the same total soil volume across a shallower profile.

Two other factors are absolutely critical to the ability of roots to grow though the entire soil profile: the type of soil that is used, and designing the system to permit adequate water into and to drain out of the soil. These features must be designed to reflect the environment in which the Silva Cells are to be placed, the types of soil resources available and the project performance expectations of trees, soil and water.

Horizontal rooting to about 4 foot depth in loam soil over river wash till. Photo courtesy of James Urban.

How to Transplant Indoor Palm Trees

There comes a time in every houseplant’s life when its pot is just getting to be too small. When a plant or tree begins to outgrow its pot, the roots can become cramped and bound. This leads to stress, and in a potted palm, stress manifests as browning leaves, leaf loss and general poor health. The difficulty in transplanting an indoor palm tree to a new, larger pot is dependent on the size of the palm; for larger trees, you might need a hand. Transplanting an indoor palm is an important part of caring for the plant, and your tree will be happy with the extra room to wiggle its roots in.

Take the potted palm outdoors or into a shop or work room where you don’t have to worry about making a bit of a mess.

Turn the pot on its side. If it is a large, heavy pot that you do not want to break, lay the pot on a soft towel or pad before turning it onto its side.

Grasp the base of the trunk and gently wiggle it free from the pot. It the palm is reluctant, take a knife or other flat, long surface, and slide it between the root ball and the side of the pot. Run the knife around the diameter of the pot to loosen the root ball.

Pull the tree free of the pot. Have a plastic bag or tarp ready to catch the root ball when it comes loose.

Fill the new pot one-half full with a mixture of potting soil and perlite or coarse sand. This will create a well-draining environment for your palm tree’s roots.

Hold the palm tree over the pot; when resting on the soil in the pot, the top of the root ball should be about 1 inch below the rim of the pot. Fill in or remove soil when necessary.

Using your potting soil and perlite mixture, fill in the space around the roots and cover the top of the root ball with 1/2 inch of soil.

Water the pot until water seeps out from the drainage holes in the bottom. Drainage holes are vitally important because they allow water to soak the soil and then seep out. This prevents a buildup of moisture around the roots, which can lead to root rot.

Transplanting

Welcome to the wonderful world of transplanting. If you have found yourself here reading this, you must either have a question about transplanting or may need some help upon the subject of transplanting. Either way, it is an important step to the growth and maturity of a palm tree or a necessity in many cases. All palm trees start out as seedlings and at one time or another, need to be transplanted into a larger pot or a yard, field, or whatever have your meduim may be. Transplanting can be made into a fun outdoor activity for the family or an individual way of bringing harmony and serenity to your landscape and/or interior design.

What is transplanting?

Transplanting is the technique of moving a plant to either a another pot or area. There are many different methods to transplanting a palm tree, so you have to be aware of the risks and hazards associated with transplanting. Transplanting is essential for mostly all palm trees which are container grown. Sooner or later the palm trees which are in the container need to be placed into a larger pot or area. This is because the roots of the palm tree have already absorbed most of the nutrients in the original pot and have amassed roots in the process. Transplanting is usually noticeably needed when the roots of the palm are exiting the drainage holes from the pot or container. If you find that your palm tree has found out an escape route through the holes, then it is time for a new pot or container. If the palm tree is too large for a pot or container, then transplanting into your yard or field is the next best thing.

Why transplant is needed?

Transplanting is needed for essential growth and longevity. Whether the palm tree has asked you, by the physical demonstration of its roots growing out of the holes or by the mere sight of the unequalled portion of palm tree to pot, it is time for a new home. Many people make mistakes and believe that there palm tree can last in the same pot for the rest of its life, this is a misconception. Most palm trees will die and whither away if not transplanted. The roots are what bring nutrients up into the palm tree itself and without the proper nutrients the palm tree will begin to yellow or brown, and then soon die. Talk about roots.

Where should one transplant?

If you have chosen to transplant the palm into a larger pot, ensure that the pot has holes at the bottom for good drainage. Almost all palm trees need good drainage for them to grow and thrive. If you have chosen to transplant your palm outdoors then take the following precautions prior to making a hole. First do some research on the particular palm tree which you are transplanting and make sure that the palm tree is not to sensitive to transplanting and if it is, then take your time. When you have decided to transplant, imagine the area in which the palm tree would be placed and how it will grow. An easy method of imagining is actually taking the palm tree out to the area and observing it from a distance. Be cognizant of the over-all growth of the palm tree, whether in a couple of years it is going to grow outward or upward, it is very important. Also, the amount of sunlight it will now be receiving in its new area is a key factor to the overall health and well-being of the palm tree. Irrigation also plays a dire roll in the overall outcome of the transplant. Some palm trees need plenty water and some don’t need hardly any water at all. Some palm trees can die if watered on the trunk and some palm trees thrive when watered on the trunk. So, it is important to have in mind the amount of water your palm tree will need and make the adequate adjustments to provide that water needed.

When should one transplant?

The ideal time or season to transplant is during the spring; however palm trees can be planted year round under the right conditions. Many people purchase their palm trees during fall season in order to receive fall prices. Many discount nurseries and farms provide fall prices for the shortage of sales. These prices in turn provide the customer a great opportunity for not only a great price but also some time with having the palm tree placed indoors. Many people have also become more courteous to the environment by purchasing live palm trees such as the Christmas Palm tree for Christmas. By purchasing a palm tree instead of an actual Christmas tree, you save the environment from losing a tree. At the same time you help the environment by planting the palm tree in your yard or keeping it in the pot for the next year, it’s a more eco-friendly approach to the New Year. During the night time to plant!

In order for a palm tree to thrive it is fundamentally important it has three necessities; soil, water, and sunlight. All other procedures and additives provide great benefits for the palm trees success in its new home. Remember that transplanting is a fun activity whether its for your self or with your family. So go out and enjoy yourself!

Transplanting Palm Pups – Propagate Palm Trees With Pups

A wide variety of palms, like sago palms, date palms or ponytail palms, will produce offshoots that are commonly known as pups. These palm pups are an excellent way to propagate the plant, but you need to know how to transplant a palm pup from the mother plant. Below you will find the steps for transplanting palm pups and tips for growing palm pups once you have transplanted them.
How to Transplant a Palm Pup
Before you remove a palm pup from the mother plant, you need to make sure that the palm pup is large enough to be taken from the mother plant. A palm offshoot should stay on the mother plant for at least one year. Allowing it to stay two to five years is ideal though, as this will allow the palm pup to develop its own healthy root system, which will in turn increase your success rate with transplanting the palm pups.
Also, the more pups a palm tree has, the slower the pups will grow. If you plan on transplanting palm pups from a palm tree that has several pups, you may be best off selecting one to two of the strongest pups and removing the others.
To check to see if a palm pup is ready to be transplanted, remove some of the dirt around the palm pup. Do this carefully, as damage palm pup roots tend to die back and this will set the pup back. Look for developed roots on the palm pup. If the pup has roots, it can be transplanted. But keep in mind, more roots equals a better transplant so if the roots are sparse, you may want to wait longer. Once the palm pups have a sufficient root system, they are ready to be removed from the mother tree. First, remove the dirt from around the palm pup, making sure not to damage the roots. We recommend that you leave a ball of soil intact around the main root ball to help minimize damage to the roots. After the soil is removed, use a sharp knife to cut the palm pup away from the mother plant. Make sure that the palm pup comes away from the mother plant with plenty of roots.
Tips for Growing Palm Pups
Once the palm pup is removed from the mother plant, move it immediately to a container filled with damp, nutrient rich potting soil. When you plant the palm pup, it should sit with the base with the start of the leaves above the soil line. After the palm pup is in the container, cover the container with a plastic bag. Do not allow the plastic to touch the growing palm pup. Using sticks to keep the plastic off the palm pup is helpful. Place the palm pup in a location where it will get bright but indirect light. Check the transplanted palm pup frequently to make sure the soil stays moist.
Once you see that the palm pup is putting out growth on its own, you can remove the plastic bag. You can transplant your established palm pup into the ground in either the spring or the fall. Make sure to provide plenty of water to your palm pup for at least the first year after it has been moved into the ground.

10 Drain Clogging Plants that Will Cost You Thousands

Spring has officially sprung (in the southern hemisphere anyway) and with that people are starting to garden and plant new plants. But most people don’t take into account their plumbing when planting until it’s too late. Whilst all trees have root systems that can be potentially dangerous to plumbing, some are much more likely than others.

Plants can’t be all to blame though, the root system of a plant is designed to track down moisture, and that’s exactly what plumbing transports, moisture. There are some types of plants that you should avoid planting near your plumbing.

10Birch Trees

Birch trees can be big, very big, in excess of 50 feet straight up. This massive height contributes to the problem, a Birch Trees root system wide and flat and covers a substantial area and causes havoc on pipes.

09Willow Trees

Willow Trees natural habitat is one of high levels of moisture such as river banks. Because of this most backyards don’t have a suitable supply of water to sustain a Willow and the root systems go hunting for your pipes causing huge amounts of damage and blockages.

08Oak Trees

Oak Trees are some of the biggest and oldest trees in the world. They are slow growing and so are their root systems. Oak trees how ever have a main root called a “tap root” which grows straight down into the ground in search of moisture. Once the tree begins to mature, other roots start growing laterally from the plant and these are the roots that cause havoc for plumbing.

07Magnolia Trees

Magnolia Trees have an amazing fragrance, and an amazing systems of roots that cause massive damage to plumbing. Magnolia roots are long, thick and rope like in appearance and structure. They grow along the ground and create havoc on plumbing that is relatively shallow.

06Citrus Trees (Lemons, Oranges, Mangoes etc.)

Like willow trees, citrus tree require large amounts of water to grow successfully, and most backyards don’t have substantial moisture in the soil, so the root systems hunt down your plumbing and get the moisture you need elsewhere. Citrus trees are such a big problem, that some home owner associations actually ban them from being planted in yards.

05Boxwood Shrubs

Boxwood shrubs are often planted on property boundaries as a makeshift fence, this is also where some of the most venerable plumbing is and due to their shallow root system the two clash quite often.

04Palm Tree’s

Unlike the other plants on this list the issues with palm trees isn’t the roots, it’s the fruit and seeds. These fruits and seeds get dropped and block utters downpipes and drains. This causes blockages, flooding and damage to pipes.

03Liquidambar

This tree is a popular choice due to its stunning appearance, but plant it near pipes and you will have problems, Liquidambar has fast growing invasive roots which can infiltrate and damage pipes fast. In addition this tree is deciduous and drops its leaves in the autumn, cause blocked gutters and down pipes.

02Eucalyptus Trees (Gum Tree)

There are a number varieties of gum tree’s growing in Australia, and has a far-reaching and aggressive root system. These trees can be prone to topple in strong wind and storms and the root systems are known to rip out undergrownd pipes in the process.

01Gingko Biloba

Prehistoric tree with fan shaped leaves able to grow 21 metres tall. The fruit can drop and not only does it smell disgusting (like dog poo or vomit) but it can block guttering and drains.

Whilst these species of plant are just some of the ones that can cause problems, essentially any tree or plant can block your pipes. But that’s not to say that you shouldn’t be gardening or planting plants, just be aware of what you are planting and its location in relation to your plumbing.

If it’s already too late and your plumbing has already been infiltrated by roots, Jetset Plumbing High Pressure Water Jetter and CCTV cameras can locate and blast away any blockages in no time. Contact your local Brisbane plumber today.

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This will be the first post in an ongoing series that will be dedicated to palm tree growing tips. I remember back when I first started growing palm trees and tried doing research on the subject, a lot of the advice I am going to share wasn’t readily available. Much of it I had to experience on my own. Over the last ten years I have learned quite a bit through both trial and error and by having such good friends that have been growing palm trees much longer than I have. First up in the series of palm tree growing tips: Mounding.

I define “mounding” as the method of adding a moisture-retaining layer around the base of the palm tree to stimulate new root growth and protect new root initials that will develop. The desired outcome with mounding is to create a larger, more robust root zone, which proves crucial to a palm tree’s overall health. A larger root zone will also vastly improve drought tolerance in your palm. I recognize two defined instances with palm growth habit where mounding is needed.

The first instance of a palm that will benefit from the mounding method is an “Exposed Root Planting.”

The second instance of a palm that will benefit from the mounding method is an “Air-girdled Planting.”

What I consider to be the exemplar of palm growth habit in Mediterranean climates is when no palm roots are exposed and where the base of the palm is wider than the stem above it. It is to this example below that we should strive.

Before I can discuss the concept of mounding, a little understanding of palm root biology is needed. To start with, all palm roots are adventitious. Simply put, this means that they grow directly from the stem rather than from other larger roots like in most other plants. This adventitious root system is made up of numerous nonwoody, primary roots that grow directly out of the base of the palm trunk in an area that we call the root initiation zone (RIZ). The root initiation zone is actually a restricted area. No roots can form above an indeterminate point on the stem, and palm trees can not create new primary roots from older, larger established roots below it. Having insight into the RIZ is key to understanding the method of mounding.

Palm roots emerge from the stem at their final thickness. This means they are incapable of any secondary growth like you find in most other plants. Most palm tree roots do branch, but remember that the primary root can not expand. This is one of the reasons a palm tree won’t crack your sidewalk like a Ficus tree will. The roots you see in the photo below will never get any fatter.

The stub of a new root that emerges from the RIZ is called a “root initial.” If these root initials are in soil or some other moist environment (compost, mulch, leaf litter, water) they will continue to develop and grow into functioning roots that the palm tree needs for water and nutrient uptake, plus stability in the ground. Because Mediterranean climates have dry periods and/or low humidity, keeping these root initials “wet” is much more important than if the palm tree were growing in a wetter environment.

Some palm tree species actually have root initials that will develop from the above ground part of the RIZ. An example of this phenomenon can be found on older Canary Island Date Palms (Phoenix canariensis) like below.

In these two Canary Island Date Palms above, this mass of aerial root stubs (inactive root initials) did not come in contact with the soil, so they became arrested. However, if you threw some mulch or soil over them, they would become active again and start growing.

Now that you have an understanding of palm roots, I can explain the mounding concept and its importance. Earlier I told you that I describe mounding as the method of adding a moisture-retaining layer around the base of the palm tree to stimulate new root growth and protect new root initials that will develop. When you mound, this moisture retaining layer you are adding can include things such as native soil, mulch, compost, sand, rock or straw. Which you choose depends on two factors: 1) If the palm tree already has visibly active or inactive root initials showing, or has exposed roots showing, you can use a heavier option for the mounding layer like native soil or compost. 2) Plants that are air-girdled should have a more airy and faster draining layer mounded around its base. Something like mulch or decomposed granite (DG) will work great. When in doubt on what to use, err on the side of a faster draining option.

The first infographic diagramed an “Exposed Root Planting.” This basically means that anytime you have a palm tree cultivated in your yard and you see exposed roots or root initials, it is not an ideal growing condition. Some palms are stilt-root palms and in that case this would be irrelevant. However, in a Mediterranean climate there are maybe only one or two stilt-root palms that grow here, so I wouldn’t worry about them. The bottom line is that palms want to have their roots covered—whether it be with mulch in cultivation or leaf-litter in habitat.

Some palm trees, like the Canary Island Date Palm for example, come from drier areas so the root can handle being exposed. However, many palm trees do not come from dry environments and when their roots or root initials hit dry air, it can cause them to stop growing or even die. Below, this Ravenea rivularis in my garden shows how exposed roots and root initials became damaged when not protected from the environment. In this case, direct sun and low humidity were the causes of the damage and death of many of the roots shown. However, damage can also come from gardening tools, foot traffic or other means.

Mounding an “Exposed Root Planting” not only helps generate more roots from the RIZ, but the added protection from injury also helps with overall plant health. Anytime a plant is injured it greatly increases its chances of picking up a pathogen. Fungus loves entering palms through damaged roots and trunks. In fact, some of the worst palm fungus like Fusarium wilt, Thielaviopsis trunk rot and Pink rot enter palms through injuries.

The second infographic from above diagramed an “Air-girdled Planting.” This is a term I coined describing the phenomenon in palm development where the stem of the palm grows fatter than its base found at the soil level. The palm tree will actually display a pinched (girdled) look to it. Some species of palm trees growing in Mediterranean climates will actually not send out any new root initials due to the fact there is no moist area for these new root initials to develop into. However, while the palm may not be pushing out any new roots to fatten the base of the stem, the trunk is still expanding above the RIZ. This is mostly seen in the more tropical palms that we grow, where the palm tree is planted a little too high above the soil line. Because of this, much of the RIZ is actually above ground.

Here we see a slight air-girdling of a Roystonea borinquena found in my yard just before I mounded it. You can see a slight pinching of the base at the soil line.

I believe that most palm trees will not send out new root initials because the tree knows they can not develop while exposed to the environment. It is our job to alleviate this, and mounding does just that. Mounding increases the moisture-retaining layer to a height where we guesstimate the top of the RIZ is located. Once the palm has been mounded it will quickly provide the right environment for new root initials to develop. By bringing the moisture-retaining layer up, you have also increased the surface area from where the palm roots can grow. The red line in the picture below of my Archontophoenix alexandrae illustrates the larger surface area where the new soil level would be mounded above the current soil level (blue line).

The height of your mounding will depend on the palm tree on which you wish to initiate additional root development. A palm tree with visibly active or inactive root initials showing, or one that has exposed roots showing, should be mounded two inches above the visible root line. For air-girdled palms you should mound up to a point just below where the girdling first appears. The red line in the photos above and below represents the height to which you would mound. You will most likely find that after a few years your once air-girdled palm will develop exposed roots or root initials and need to be mounded once again. When in doubt as to what height to mound, err on the side of lower rather than higher. Mounding too high can lead to stem rot in some palm trees. So play it safe.

Now for some proof. Here are a few examples showing the benefits mounding has provided in my garden.

The first comparison is of an air-girdled Foxy Lady Palm. The palm below clearly shows air-girdling and also the beginning stages of an exposed root planting. The red line diagrams how far up the stem I will be mounding this palm in the future.

For comparison, about four years ago this Foxy Lady Palm below looked just like the one in the last photo. You can see how fat the base of the stem is now compared to the air-girdled palm shown above. Thanks to mounding, this palm is so happy that the “bark” has actually flared out. This is the direct result of the development of numerous new roots underneath it that had more soil to grow into. If you look closely you can see a few roots becoming exposed. I will actually be mounding this palm again with another few inches of DG and mulch.

Earlier I wrote that stability in the ground is another of the benefits of mounding. This stability from mounding comes from forcing the development of more roots to help anchor the palm into the ground. One palm tree that is notorious for being wobbly and easily blown over in high winds is Syagrus botryophora. A year ago my palm below was showing signs of needing mounding, as it had exposed roots and inactive root initials coming out the base. So I built up four inches of DG and two inches of mulch as the mounding layer around the base.

Pulling away that mounding layer, you can now see the results. Numerous fresh new roots with many more developing. Only one short year ago I could rock this palm in the ground. It was that wobbly. Now it is so locked into place that it no longer sways in high winds.

Here is the last example in this palm tree growing tips post to show you how well mounding works. This Roystonea regia had a slight air girdle showing three months ago. I put down some DG and mulch around the base and you can now see it has already started to develop new roots. These new roots can only benefit this palm.

What are we looking for as an end result of the mounding process? Something like this Archontophoenix alexandrae in my yard that is showing off the almost perfect shape to the base of a trunk of an ideally grown palm. This is what I consider an exemplar of palm growth from the third infographic at the beginning of this post. I mounded this palm two years ago and you can see how fat the base of the trunk is on this palm in comparison to the other Archontophoenix alexandrae I posted a few pictures up. Cheers.

As you gain experience over time from mounding, you will learn what works best for you in your garden. If you have any additional tips or comments about mounding, I would love for you to share them below.

Tagged: Gardening Tips, Palm Trees

September 3, 2014

The Four Worst Trees To Plant In Your Garden

1. Eucalyptus tree (gum tree)

Eucalyptus has many varying types, differing in height, shape, and colour, but they all have similar characteristics that make them unsuitable for planting near a home on your property:

  • This species of tree can grow quite large, and both root system and canopy will pose possible issues.
  • Eucalyptus trees’ root systems can be quite aggressive and far-reaching, and it is common for retaining walls or building foundations to be disturbed by searching roots. Roots can travel dozens metres, and further than their dripline.
  • Branches are likely to die off but not fall straight away. This leaves dangerous objects that may damage a person or property during storms or times of strong wind. Often eucalyptus branches can just become weak and fall to the ground without any external help.
  • Often, single large gum tree specimens are lone survivors of development. Where once they were a part of a larger stand of trees, naturally designed to withstand strong wind and storms, now alone and possibly structurally weak.
  • It is vital to have a qualified arborist to maintain your tree at least every two years to remove dead branches and check the structural integrity of the tree for safety.

2. Ficus species (fig tree)

Ficus plants are common as house ornament specimens in pots, and as neat topiary ‘lollipop’ shapes by the front door. They have lush green leaves and straight white trunks – they really are a beautiful plant. But as most potted plants go, once neglected they are thrown out to the yard where the roots break through the pot to the ground. Sometimes they are planted neatly in the ground, and maintained as a topiary.

  • These are rainforest giants that will grow 20-30 metres tall and wide. It is not a tree for a suburban yard.
  • The root system is very aggressive and strong and will easily knock down a masonry retaining wall. Even root barriers will struggle with this species.

3. Palms

Palms are beautiful plants in a domestic situation while young. The fronds are visible and can create a tropical oasis feeling in the yard or next to the pool. As they get older however, the problems begin:

  • Palm canopies grow higher and higher, until all you can see is a ‘telephone pole’ in the garden.
  • Palm fronds can be large, and falling down on windy days are disturbing and messy.
  • Some species of plam tree produce dates or fruit, that either attract annoying wildlife (screeching bats) or create a mess around the pool or in the pool (clogging filter systems).
  • If planted too close, the expanding trunk and roots of a palm tree will lift pavers and have been known to damage retaining walls.

4. Deciduous trees

Frangipani trees, Pink Trumpet trees, Golden Rain trees, Flame trees, Liquid Amber trees and other deciduous trees are wonderful features in the garden and can provide a spectacle in the turning of the seasons. Be careful of where these are planted though:

  • Dropping leaves can clog gutters and cause continuing damage if not cleaned out regularly.
  • Leaves on shady, wet paths can also cause injury to pedestrians if not frequently removed.

If you’re even thinking of planting any of these trees, call me to chat about your landscape design. Head back here next week to find out the four best trees to plant! (If you forget, why not follow us on Facebook, Twitter or LinkedIn).

Photo credits: 1: Averain, 2: Mosman Council, 3: ishane, 4: robynejay

Planting Palms

Now that it’s spring (at least in the top half of the world), it’s time to start thinking about planting your palms. It is best to plant when it’s warm, and going to be warm for at least 6 months. Super cold hardy palms will survive winter planting in somewhat marginal climates, but still they will not grown new roots well until the soil is above 65F. Otherwise it will take longer for the planted palm to become established and that may keep open the window for secondary problems to develop. Fortunately many palm roots are very shallow which allows them to get sufficiently warmed up as the weather warms (deep soil does not often warm much past 65F anyway). In the tropics, the warmth is less of a concern and one can plant all year long if there is sufficient water available. In the tropics it is best to plant at the beginning of the rainy season.

An important thing to consider before actually planting your palm is proper placement. This may seem to be a simple concept, but even after 15 years of planting palms, I still make many of the same mistakes concerning proper placement. You have to know your palm’s need for sun and shade and be sure not to plant shade loving palms where they will get noon or afternoon sun, or plant your sun-needy palms where they will get too much shade. Remember that though your palm may be small now, it will grow so you also have to plan for future possible sun exposure, or loss of sun if planting faster growing palms nearby. One also needs to remember that palms will grow tall, and sometimes wide, which can affect one’s view (or one’s neighbor’s view) in the future. Some palms also take up a huge amount of room even though they may be small right now (eg. Phoenix canariensis may seem great now in its 15 gallon pot, but in 10 years it will have a spread of 25′ or more and shade out everything in the vicinity from sun for many years to come.

Caryota gigas is a big palm once it forms a trun, but as a seedling, one might be tempted to plant these close together. In the middle photo one can see how far these were spaced at this arboretum- sure looks like plenty to me… I would never have placed them even that far apart. Yet in the last photo one can see how really close together these massive palms ended up being… probably should’ve been planted even further apart!

If one has the room, planting palms in groups is a nice landscaping touch, as was done in the above Hawaiian garden (mass plantings of Dypsis decipiens and Bismarckias, Marojejyas, and Royals)

Palms ideally should be acclimated before planting. Many of the more common hardy species are ready to go in the ground no matter where they came from, but less common species and those grown in hot houses may be in for a shock planting right in the ground. These will need some acclimation to sunlight by putting them out in partial shade (shade cloth works well) for 6 months, up to a year or more. I never wait this long, but I also burn a lot of palm leaves. Burn ALL the leaves and you can lose your palm, though.

If you are lucky enough to live in the tropics, you can plant a palm out at almost any size and it will have a decent chance of survival, as long as something doesn’t come along and eat it. But if you live in a more marginal zone, generally the larger the palm the better (up to a point… some species large enough to have to be in a box, or transplanted as an adult, are much more likely to be severely stressed by the move and survival percentage could drop drastically.

Nursery in Hawaii- these palms can be planted out at just about any size; Bismarckias of various sizes ready for planting in southern California- any larger than these and these palms can have trouble with a routine planting; last photo shows some boxed palms at a nursery ready for planting- all these palms are pretty easy to plant

Most palms that are to be planted are in pots or boxes at the time of planting. Unlike what is the case with most other trees, palms seem to like being in small containers and most live happily in those containers that may seem far too small for them, and for amazing amounts of time. Palms have small roots compared to most other trees and most of these roots are the same size and fairly non-complex. Palms don’t grow a real tap root nor to their roots branch much or get very thick (and don’t thicken or enlarge with age). They simply produce more and more roots, and some more branches, as they age, and the roots get longer and grow deeper or more laterally. And for some reason palms seem to like their roots crammed into a small space and live happily in a pot until the roots so far out-mass the soil that the palm can no longer absorb sufficient micronutrients and/or water runs through the pot so fast the roots cannot take enough up. Then it’s time to repot or plant.

note root exposure- this palm is completely pot bound, yet healthy and happy

Why is knowing this important? When one plants a tree, one usually digs a fairly large hole, often much larger than the root ball size (aka pot size). Palm roots do NOT like being messed with or disturbed. When taking a palm out of its pot, the more root bound the palm is, the less this procedure will upset them, and the less this activity will set back the palm. One should never take a palm out of a pot and try to ‘unwind’ or open up the root ball the way one might with other root-bound trees or shrubs. This palm root manipulation can be fatal to the palm. It is far better to leave the root bound root ball intact and plant it as such.

Three palms I have planted, all root bound to some degree (see roots coming from bottom of pot in first photo)

In these three palms, the rootball is developed enough to maintain the shape of the pot. If it’s not, the palm is probably being planted prematurely. The third palm is completely rootbound to the point of having little soil left in the pot, but still the palm was doing fine. Palms with this degree of root compaction have the least set back when planted in the ground.

Also, unless one has horrible soil and plans on digging such a huge, deep and wide hole that the palm roots will not extend to the native soil for years, digging a hole not much larger or deeper than the pot itself is sufficient and even recommended. This not only mean less work, but is actually better for the palm (in most cases). This may seem counterintuitive, but recent research done on a variety of fairly hardy palms by Dr. Hodel in California showed this to be the case.

I usually dig a hole with a post hole digger- and save the dug dirt in the pot for putting back in the hole. A post-hole digger allows one to dig a hole nearly exactly the size and shape of the root ball.

Another strategy that was used for a long time by some rogue palm growers in southern California was ‘pot planting’. This was first started by some palm growers in the 70s after they noticed that their palms they had for years in the same pots grew into the ground eventually and seemed no worse the wear for the bulk of their root mass to be still stuck in the same old pots. Over time most would split the black plastic or clay as the palm matured to its adult girth, but the palms were never noticeably set back by this occurrence. So some of these growers just started to dig holes about the size of the pots and dump the whole pot right into the ground. This had several noticeable advantages. One was obviously simplicity- digging the hole the size of the pot made for smaller, easier holes, and there was not effort spent on trying to remove the palm from the pot (this conclusion was reache 20 years prior to Dr. Hodel’s research). Another was stability as most of these palms were pretty stable and secure in the pots that were planted, but removing a palm from a pot often left one with a top-heavy plant now needing some extra security and support, particularly in windy weather, and without that added support, many palms would simply blow over before becoming established if not staked up. But lastly, and most importantly, since palms do not like to have their roots messed with, this meant NO root disturbance at all.

Unfortunately over the long haul, pot planting did seem to slow a lot of these palms down at some point during their growth, particularly in warmer, more humid climates like in Florida, though rarely did it have a lethal effect. Palms grow so much slower in a cool climate like California that this setback was rarely noticed. Large, fast-growing sturdy species had no problems tearing through the pot as their roots grew, but smaller, less fast growing species would sometimes sulk and go through a ‘sad’ period, as the roots perhaps would be reluctant to grow through the holes into the surrounding soil and never be able to split the pots. Either way, it became a fad that came and went, though some growers still use that technique to this day.

Many other palm experts believe, particularly for marginal palms, that digging up a very large area (both depth-wise and in width) and replacing all soil with well amended, very rich and excellently draining soils. The idea behind this process is such a large area of reworked soil will provide a better, nutritious and ideal basis which the palm can grow in for many years. And once the palm is finally large enough to have its roots extend into the surrounding, less optimal native soils, it will be so well established that this will not be a problem. This is obviously a very labor-intensive and costly process involving a lot more soil to be purchased, and a lot more effort to being used to support the palms during their period of adjustment (new soil doesn’t tend to support palms from blowing over in windy weather unfortunately), so I recommend this only for very important and marginal palms, as most palms do not normally require this sort of preparation.

Assuming one is planting a relatively common and hardy species, the narrow-hole strategy seems to make the best sense. So now that one has planted the palm in a narrow hole not much larger than the original root ball, what does one put back in the hole? Again, the answer seems a bit counter-intuitive. Dr. Hodel found in his research that there was little if any advantage to putting in amended soil versus the same soil that was dug out of the hole to begin with. In fact, there sometimes was a disadvantage to doing this as the roots, discovering the ‘good’ but different soil, would eventually grow into it, but then were ‘reluctant’ to grow beyond it. While roots that were placed in a hole backfilled with the same soil that was dug out of the hole were much less ‘reluctant’ to grow into the surrounding soils beyond the backfilled soil. These palms grew faster and became established more quickly than did palms with amended soil added to the holes. So do NOT amend soil that was taken out of the original hole- just replace it as is. Adding mulch to the top of the soil is still highly recommended, however.

Whether or not this holds for palms planted in sandy soils typical of the southeast is unknown, as Hodel’s research was done on California palms planted in more clay-like soils. Sandy soils tend to be much more nutrient deficient, so amending such soils might be recommended. Palms roots meet little resistance in such soils and are more likely to benefit from the added nutrients.

Watering right after planting is important, but the goal is to make the soil evenly moist, not to drown the roots. If the soil that is dug holds water for hours, or worse, days (good idea to test this before sticking a palm in it), then one needs to dig a lot deeper until draining soil is reached, or until the hole is deep enough to back fill with some gravel and/or sand. A drainage pipe extending from the bottom of the hole to the surface also works well to keep new holes like this from just filling with water and drowning the new roots. Water the newly planted palm frequently for a good 6 months.

However, do not fertilize right after planting as most palms roots will not be ready to utilize fertilizers for up to 6 months, and one may not only waste a lot of money on fertilizer, but sometimes premature fertilization can burn the inactive roots.

Of course there are many exceptions to these simple rules as there are many palms that grow differently than the common palms one most often encounters in cultivation.

Other aspects of planting palms, particularly larger palms, include root pruning, leaf pruning, moving, watering etc. Watering is the easiest to cover- almost all palms require a lot of water, particularly as they are becoming established. However, overwatering, particularly in clay, of palms just moved can sometimes be a problem as the roots of just-moved palms are slow to take up water until they can grow new rootlets, and one can drown a palm in the mean time. But under-watering, rather than overwatering is much more common, particularly in well draining soils, as water tends to drain away from the root ball quickly in a newly planted palm. The old, disturbed roots are unable to take up any water from the surrounding soil until they actually grow into the surrounding soil. Large trunked palms have a lot of water reserve in them and many species will tolerate some drying out before becoming lethally dehydrated. Still, it is best to avoid this stress as these palms will then lose most of their leaves and take years to recover completely if at all.

For most hardy palms, one need not take a large root ball. Most professionals take a ‘shovel-width’ from the trunk and cut down about 2-3′ feet (more in very large tall palms). Then the palms are usually extracted with a crane, being extra careful not to bend the trunk and damage the ‘heart’ (particularly with sensitive-trunked species like Archontophoenix- else the palm will die), move to the new site and plant that same day (drying out of roots is a big concern). Be sure to transplant at the same depth the palm was originally planted at (some try to save money and time on staking up newly planted palms by planting them a foot or so deeper for extra stability, but this can lead to root suffocation and loss of the palm). Some palms are unique in their root-growing properties, with Sabals being one example. No matter how careful one is when digging out the root ball, all the roots will die back to the trunk and all new roots will have to be grown. Fortunately these palms tolerate this well (if having significant trunk already) and so root ball size does not matter with this genus. Coconut palms can also be dug up with root balls of very small size as roots grow fast and well with any size root ball.

Even fairly large palms like these Phoenix and Sabal can be moved with relatively dinky rootballs

Some species of palm are extremely sensitive to being moved, and transplanting them often results in a lot work and money for a dead palm. Braheas, Bismarckias, Archontophoenix and Rhopalostylis are all genera that are well known as difficult palms to move. All these palms should probably be root pruned, something one rarely needs to do for most hardier palms. Getting as large a root ball as possible within limits is recommended is one technique, but rarely practical… so root pruning is another option. The palm should be watered well for months. Then the roots are cut at a certain distance (depends on size of palm or crown) from the trunk and allowed time to heal and reform the water-absorbing rootlets- a process that can take up to a year. Then the palm is moved with its new smaller but active and healthy root ball- this will still damage the deepest roots, but at least now the lateral roots will be intact and relatively undamaged, and be able to take over for the palm in its new hole as the deeper roots struggle to recover. Still, with these palms one might find that starting over is best as most of these will die during the move.

King palms, Bismarckias and Braheas are all poor palms to try to move at these sizes… though some manage to do it successfully

Though one may have a nice mature Rhopalostylis if one could move it successfully, but getting a seedling in a large pot would probably be the better investment as these rarely survive a move

Cutting the leaves of palms that are to be moved is a common practice in order to decrease water loss through transpiration, though recommendations on how much to cut varies. Cut too many leaves and most palms will be unable to feed themselves. Cut too little or none and the theory is that will leave too much surface for desiccation to occur (this is only a theory, however, and in practice this may not be the case). Also many tie the leaves up in an effort to reduce the subsequent transpiration and desiccation. However, this has been shown by Hodel to have little positive or negative effect.

Phoenix canariensis with leaves tied up after a move

The actual moving of large palms is not something I have never done, but there are many professional services that have lots of experience doing this, and it is doubtful anyone reading this will try to move their own giant palms without help. Either way, as mentioned already, care must be taken not to bend or crack the trunk as that will often lead to death to the palm. It is amazing however that huge palms such as mature Jubaeas and Phoenix canariensis, which weigh many many tons tolerate moving so well. These palms are often worth thousands so it pays to be careful and do a good job moving them. If you are buying such a palm, know that there is a risk of survival and palms can often look good for up to 2 years before they die from the move. And don’t ever move a Phoenix canariensis into the same spot in which one recently died without making sure it did not die of fusarium wilt (a very contagious fungal disease of certain species) or you may end up with another expensive dead palm completely unrelated to anything the move itself had to do with.

Large operation and experienced movers moving palms in Thailand

When planting large trees, it is recommended to put a lot of gravel/ sand or similar material at the bottom of the hole 1-2′ in depth before putting in some back fill. This keeps the palm from drowning in water in soils that do not drain well. This seems to more important for much larger palms than it is for small ones that can be moved about by hand. Also used in this giant palm holes are aeration pipes that often extend below the gravel from one side of the hole to the other, and then rise up out of the holes above soil level.

Support will be needed for palms with any significant trunk for up to a year or more. Just don’t use nails or screws to attach boards or planks to palm trunks as these holes will never heal and allow for infection or parasites to enter into the palm.

Phoenix canariensis and Sabal palmettos being supported after planting in Florida

Planting palms from seed directly into the ground works with some hardy species, but I would only recommend this if one lives in a zone that is excellent for this species (do not plant marginal species into the ground as most all will fail to thrive). Coconuts are particularly easy to plant if one lives in a tropical climate as these will germinate quickly and root right where they fall. Washingtonias grow just about anywhere a seed falls (they are considered a common weed in southern California). Queen and King palms can be similarly planted with seed with a reasonable expectation of germination and growth as long as there is sufficient water and warmth. But in most other species, successful germination usually improves with a bit more effort and care. This is a topic for a future article, however.

King and Queen palms ‘plant themselves’ often, as seed that falls will often germinate. Most of these seedlings need to be ‘unplanted’. Last photo is of some Chamaedorea seedlings I germinated, and lazily planted out in a huge bunch like this. Most individuals will be lost eventually, but palms tolerate being planted in clumps like this far better than do most other trees.

Coconut palms are one of the easiest palms to plant, as they tend to root whereever one sets them down (as long as one lives in the right climate!)

In summary, palms are pretty easy and tolerant plants in terms of planting from pots or transplanting. If some simple steps are followed, most of one’s palm planting experiences should go well.

For an excellent write up on transplanting palms see: http://edis.ifas.ufl.edu/ep001

How Fast Do Palm Trees Grow In Arizona?

by Phoenix Trim-A-Tree
in Palm Trees, Tree Care, Tree Planting
14 Mar 2017

A lot of Phoenix valley residents are asking the question: “How fast do palm trees grow in Arizona?” How fast your palm will grow depends on the species of palm you have. Some types of palms grow as much as 2 or 3 feet per year while others might only grow to be 5 feet high after several years. When you are planning your landscape pay close attention to the species and plan for how big and fast they will grow.

The growth rate of palm trees depend on a various factors which either encourage or discourage growth. Factors range from planting location, irrigation, fertilizing, and pruning. The different species all have different needs for these variables so it is a good plan to talk with your local palm tree nursery to find out how much the species you are planning on planting, or already have, will need. If you need help with Palm Tree Trimming or any palm tree related care, call Phoenix Trim-A-Tree.

Palm Growth Rates

When conditions are idea with the watering, fertilizer, pruning and location you can expect healthy growth in your palm trees. Different species of palm trees grow at different rates. See below to get an idea of average growth rates for palm trees.

Queen Palm

The queen palm when planted in USDA hardiness zones 9 through 11 grows about 2 feet each year. This means if you buy a 15 gallon plant you can expect a 25 foot Queen Palm in about 10 years. This is considered a fairly high growth speed.

King Palm

Another fast growing palm is the King Palm. They grow quickly in soil that has good moisture and plenty of nutrition. The growth rate for the King Palm is nearly 2 feet each year. This makes it a little slower than the Queen Palm. This rate can be faster when the palm is planted in partial shade as it will grow faster towards light.

Mexican Fan Palm

These palm trees are one of the faster growing palm trees that is common in Arizona. They can reach dizzying heights for 70 to 100 feet which is typically too tall for most residential yards. Under ideal conditions you can expect an incredible 4 feet of growth per year from these palms. Their height and quick grow makes them very popular for commercial use or in public parks.

Mediterranean Palm

Also known as the European Fan Palm these palms are fairly slow growing. They grow about 6 inches a year and reach their mature height of 20 feet quiet slowly. They are still incredibly popular as they have a beautiful fronds and bark. They also make a great addition to most residential landscapes as they do not over power the visual presentation of the landscaping or home.

Foxtail Palms

The Foxtail palm is a fast growing palm tree and under ideal conditions it can grow from 2 to 3 feet each year. They can grow to about 30 feet high and will reach that height in about 10 years. This is a great option for people looking for a great canopy and quick growing palm tree. This tree also features a deep root stem which makes it quiet drought tolerant.

Palm Tree Trimming & Care

Phoenix Trim-A-Tree takes care of palm trees anywhere in the Phoenix metro area to help this iconic staple of Arizona looking their best. We trim palm trees and care for the overall health by enriching the soil with the nutrients needed for them to grow tall and strong. We can also help you understand how to best water the type and size of palms you have on your property. If you have palm trees that are sick or dead they should be cared for or removed to prevent damages or injuries on your property. If you have palms allow us to care for them and keep you safe.

We also offer Palm Tree Removal for trees that are sick, dead, or pose a hazard to your landscape.

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