When to plant avocado?

Fruit & Vegetable Growing

I’ve learnt the hard way when it comes to growing avocado trees. Scroll to the end of this article to watch the VBlog (video).

Initially, back in 2006 when I planted several avos in our orchard, I thought that a foot of topsoil would be enough to grow a healthy avocado tree. All our other fruit trees were thriving so why wouldn’t avocados do the same since our climate is perfect for them?

Well, I was terribly wrong and disappointed to find the first signs of deterioration in our avocado trees after the second year in the ground. For the first 18 months our avocado trees grew fast and strong but then they began to wilt, the limbs slowly blackened, and the leaves started falling off exposing the skin of the tree to the harsh sunlight causing burns and scarring.

Over a period of about 12 – 18 months, all our avocado trees slowly perished.

So why did my avocado trees die?

To cut a long story short (because I did spend a protracted and futile time trying to save the trees) what happened was the long avocado tap root eventually grew through the topsoil and into the clay beneath. Ultimately, once an avocado sinks it’s tap root into clay soil it’s just a matter of time before it dies from root rot disease.

Clay soil when wet is sticky, gluggy, and lacks oxygen, however, it can also dry hard as rock. Avocado trees originated from rainforests where they adapted to grow in fertile black soil loose with deep organic matter and although getting lots of water this free draining growing medium allows the root system to breathe and expand.

Image above shows dying avocado tree due to root rot

Therefore, avocados have a fickle root system that responds poorly to root disturbance (so be careful when you plant them) and they won’t tolerate “hard going” (such as rock, compacted soil, or dry clay) or prolonged periods of low oxygenated sticky wet soil.

But, I have clay soil so how do I plant an avocado tree then?

There’s only one option when planting an avocado tree on a property with a clay soil base and that’s above ground on a mound or raised garden bed. This method keeps the taproot out of danger and allows the feeder roots to still explore the topsoil and get the nourishment it requires without becoming waterlogged.

To answer this more completely here’s a question I received from one of you guys:

Hi Mark,

Just wanted to ask a quick question. I have bought 2 avocado trees (Bacon & Lamb Hass). Live in Sydney. My soil underneath is hard orange/red clay about 50 cm below my topsoil.

Just wanted your opinion on whether I should use a raised bed of about 80cm in Height and 1.5m x 1.5m per plant, or whether I should just mound. Wanted to hear your experience. I prefer the garden bed as it looks cleaner in a suburban house. I’ll probably dig up a 75cm to a metre of the clay under the garden bed and replace with compost and potting mix. I did some research and indicated that with 700mm rainfall (avg for west Sydney) needed approximately 1.5 of free draining soil. I’m a bit worried that digging into the clay may produce a well or drain for rainwater to sit in. I have planted mangoes, oranges, pomegranate and apples in the same method, and they are going ok.

I know you tried to grow in a raised bed so just wanted to hear whether it was the raised bed that caused an issue.

Answer:

Firstly, the main thing to focus on is the taproot of an avocado tree it’s like its lifeline and stabilising trunk under the soil which can grow straight down up to one metre deep for most medium sized backyard trees. The most important growing tip for avocados (I believe) is to ensure the taproot does not penetrate clay soil.

Therefore, if you have a topsoil of 50cm (or half a metre) then mound up the soil about 70 – 80cm above that (as you suggested) to allow for some settling so when the taproot eventually grows down it doesn’t reach the clay. Whether you use a raised garden bed or simply a mound of soil to get the height required isn’t important but yes a 1.5 x 1.5 raised bed would be perfect in my opinion. I have two avocados growing in smaller raised beds than that and they’re doing well, although, they are dwarf varieties so the root system won’t be as large as the standard types.

As far as digging into the clay goes your instinct to be “a bit worried that digging into the clay may produce a well or drain for water to sit in” is right and I know this because I have tried it.

Years ago, after several avocado failures, I dug out a massive hole (image above) and backfilled with plenty of organic matter and good soil plus clay breaker then I mounded the soil and planted the tree. What happened was the hole in the clay acted like a wicking bed and instead of draining away water it just created a wet feet environment for the roots and the tree suffered. I tried replanting the avocado tree but as careful as I was it didn’t survive very long after.

I strongly recommend not digging down into the clay at all! Rather always build up so that when the water drains through the mound and subsequent topsoil it hits the clay and gets diverted away like a slow seeping underground river rather than gather in a hole (no matter how large it is or how much good quality growing medium is thrown in).

Our oldest tree which will be 5 years old this January (2018) is an Edranol (type B) non-dwarf/full sized variety and I grew it on a mound of good quality organic matter or in other words a pile of soil about 50cm high. I’ve continued to mulch the tree well, water regularly, feed yearly with an organic fertiliser, and also top dress with several handfuls of garden lime each year because they do like sweet soil.

This season it has about 15 fruits and it seems the growing fix mounding up above the clay soil as described has worked! I should stress that our avocado trees are still not out of the woods yet because they are still relatively young and who knows what might happen. However, I’m pretty confident they will make it this time.

The research on avocado growing indicates that the longer the tree survives after planting the better chance it has to live a long healthy and productive life. Most avocado trees tend to die from poor soil-related diseases (like root rot) within the first few years and it’s uncommon for established older trees to die. It seems once a tree matures past about 3-5 years it’s pretty safe because the majority of it’s root system has not only avoided problem areas it has also developed a stronger immune system to deal with any such diseases.

On a side note, there’s another observation I made over the past 12 years that I find interesting and that’s the reshooting of the avocado tree below the graft once the grafted part had died. We had most trees that died back reshoot from the rootstock and try to regrow some failed and others I ripped out simply because I didn’t want to grow a tree that probably wouldn’t fruit anyway.

However, recently, I did leave one tree as an experiment to grow because it was out of the way in in an ornamental part of our property anyway. The grafted part of the tree died but the sucker growth is still alive and has been growing albeit slowly for the past 3 years.

I’m far from a plant expert, however, I do think that grafted avocado trees are inherently weaker than those grown from seed and therefore are more susceptible to disease particularly in the early years.

What can we make out of this observation? Well, avocado tree failure is commonly blamed on the fickle root system and that’s true; however, adding a graft to an avocado weakens the plant overall and might also be a major reason why they are notoriously difficult to grow. The alternative is to grow completely from seed to get a hardier tree but then you may have to wait over a decade for fruit at the same time running the risk that the fruit would be poor quality anyway.

My Grandparents grew an avocado tree from seed and it did finally fruit profusely after many years but the fruit was pretty stringy – edible, but not great… Once their grafted Hass avocado grew to size and started producing superior fruit they cut the old seed grown tree down.

So, until someone improves the disease resistance and hardiness of grafted avocado trees either grow them where there isn’t clay or mound them up and hope for the best!

Here is the video blog (Vblog) of this article:

Mark Valencia

Mark is the Founder of Self Sufficient Me – you can read more on our About Page and subscribe to his YouTube Channel here.

How to Grow an Avocado Tree

Container-grown avocados do well indoors.

Caring for Your Avocado Trees

Once established, avocados are simple to care for. Their large, leathery, green leaves and attractive form make them beautiful houseplants and landscape trees, even when they’re fruitless. By providing your tree’s basic needs, you help ensure its beauty and future productivity.

Watering – Avocado roots need plenty of air, so avoid overwatering. Always let container soil dry out slightly, then water thoroughly to moisten the entire root ball. If your container tree moves outdoors for summer, it may need daily watering. Container plants dry out more quickly in sun and wind — and don’t forget to bring your plant indoors once temperatures drop below 50 degrees Fahrenheit in fall.

For landscape avocados, water the entire area beneath the tree’s canopy. Water deeply and thoroughly, then allow the soil to dry out slightly before you water again. Most avocado roots stay in the top six inches of soil, which can dry out quickly. Newly planted trees may need water two to three times per week their first year. Mature avocado trees need water equal to about 2 inches of rainfall or irrigation each week during summer.1

Fertilizing – Avocados do best with plant foods designed specifically for avocados and citrus. They prefer fertilizers with higher amounts of nitrogen relative to phosphorus and potassium. That means that the first number in the N-P-K ratio on your fertilizer label should be higher than the other two.

Pennington UltraGreen Citrus & Avocado Plant Food 10-5-5 provides avocados with an ideal blend of primary nutrients plus added micronutrients, including zinc and iron, which are especially important to avocado health and growth. This premium fertilizer starts feeding immediately, then continues feeding your tree for up to four months.

Feed container avocados every 12 to 16 weeks, according to label rates based on the container size. For outdoor landscape avocados, feed in late winter, midsummer and again in early fall, according to the recommended label rate based on the tree’s age.

Avocado Tree Growing – How To Plant An Avocado Tree

Avocados are a source of vitamins and nutrients. Their popularity as a condiment or use in salads is enhanced by the sunny climates evoked by their presence on the menu. Planting avocado trees outdoors is not a viable option for most United States gardeners because of the plant’s preference for tropical to sub-tropical temperatures and frost sensitivity.

However, you can learn how to plant an avocado tree as a potted indoor plant or in a protected area outdoors to grow your own crop of this rich, versatile fruit. Warm indoor temperatures, bright sunlight and good avocado tree care can have you on your way to homemade guacamole and a host of other gustatory delights.

Avocado Information

Avocado tree growing is a fun way to introduce organic fruit for you and your family. Avocados may be medium to large trees but dwarf varieties exist for home growing. The trees have fragile limbs that are easily damaged by wind and the entire plant is very sensitive to cold conditions.

The tree is evergreen with thick, leathery leaves and produces perfect white, ivory to yellow flowers. The fruit

has a large seed or pit in the center and may be green or nearly black. Avocado information wouldn’t be complete without mentioning the three distinct groups of the fruit from which all cultivars derive. These main varieties are:

  • West Indian
  • Guatemalan
  • Mexican

How to Plant an Avocado Tree

Choose a location where there is plenty of sun exposure and well-drained soil when planting avocado trees. A location on the southern side of the home or in a dip or valley will ensure protection from winds.

Incorporate plenty of organic matter into the soil and check the soil for porosity. If you have soil that doesn’t drain well, work in sand or other gritty matter to increase its drainage.

Also, you need to leave 8 to 10 feet from buildings and up to 30 feet of space apart when planting avocado trees.

Avocado Tree Growing

Avocados do not grow true from seed but you can get an interesting plant from starting a pit. Although many gardeners have experimented with germinating a pit in a glass of water, most avocados are propagated from tip grafting and the resulting seedlings will exhibit the characteristics of the graft wood or parent plant.

Plant grafted seedlings with the graft under the soil, which is uncommon for other grafted trees. Stake young trees and keep them free of weeds while they are establishing.

Avocado Tree Care

Planting avocado trees properly is only the first step to getting fruit. Avocado tree care must include deep, thorough watering when the growing season is in full swing.

The trees benefit from fertilization in February through September. Use ammonium sulfate applications spread out over this period. In the first year after planting, apply 1/2 cup, which increases to 1 cup per month. Once the tree is two years old, application can increase to 2 cups every month.

There is no need to prune the tree except to remove dead wood in spring. You can, however, prune an avocado to maintain size, if desired. Most trees produce fruit within a couple of years.

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