How to prune cactus?

This summer has been kind to cacti and they’ve responded with new growth. My bunny ears cactus, Opuntia microdasys, put out three new pads in a matter of weeks. That is until I decided to clean the window behind it and with one slightly clumsy move all three new pads were stuck to the cleaning cloth instead.

Not such a mishap, though, as cacti are surprisingly easy things to propagate. The best time to take cuttings is summer, but I’ve had good results as late as now, and if life gives you unexpected bunny ears to propagate, or the bottom of your cactus starts to rot, then emergency cuttings are the best way to rescue the plant.

‘Remove a segment to create a new plant.’ Photograph: Getty Images

With prickly pear, bunny ears or any cactus with segments, you just have to remove a segment to create a new plant. These are some of the easiest to propagate: using either kitchen tongs or wearing thick gloves (never assume any cactus spine is going to be kind, however small) gently pick off a section. If you have a mound-forming cactus, a mammillaria or echinopsis say, then you can cut off or divide an individual head at soil level. Make a straight, clean cut with a sharp knife. If it’s a columnar cactus, slice off a good section of the head. This is the same trick for rotting bases, slice off the healthy part to save and discard the rest.

On a saucer lie the cutting carefully on its side. The exposed flesh needs to callus over before it can root, and this happens when it is exposed to air. This can take a day with a small specimen, but up to a week for a larger surface area.

Once a hard callus has formed you can put it into a small pot. Cacti need very free-draining conditions to root into. As we are going into the dormant period of growth, I suggest five-part grit and horticultural sand to one-part compost. You can test the mixture by running water through the pot to ensure it drains quickly.

Pads or segments can either sit on the soil or be placed upright. Erect cacti should remain upright in the pot. Water immediately after planting and again when the soil is completely dry; in winter this may mean watering just once, till spring. Leave the plant somewhere bright, but not in direct sunlight.

In summer, cuttings can take in 24 hours; in winter it can take as long as three or four months. You can tell if the cutting is rooting because either roots will appear through the drainage holes or the cutting will feel firm in the pot. And in spring new spines will appear.

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How to Propagate your San Pedro Cactus

How to Propagate your San Pedro Cactus….

Easy to do! In this blog I will quickly show you how to do this from your established San Pedro (or almost any columnar/tall growing cacti), as well as from a smaller potted specimen.

What you need: A knife, a piece of cardboard/towel, a container, soil, and a little time.

This a 5-6′ San Pedro planted on a slope. Notice the shorter sections where you see new tops growing. These have started in areas that have been cut prior.

Sometimes you get 1,2 and even 3 new tops growing from the recently cut areas.

This is a basic potted 18″ San Pedro, started as a 12″ cutting last summer, getting ready to have it’s top 12″ or so cut off.

Try and always use a clean knife, if cutting multiple cactus, make sure to sterilize w/ rubbing alcohol if you cut into any infected sections. (sometimes cactus get sick and start rotting in sections and you have to amputate, sterilized cutting tools are helpful so as not to spread any infection).

Now we need to dry/callous the end. If it’s sunny outside, it’s easiest to just expose the end to direct sunlight! If doing it this way, make sure you cover the length of the cactus to protect it from sunburn. As these grow upwards, when they are laid on their sides they can get burned! I usually just put a piece of cardboard along it’s length. I usually just leave in the sun like this for 1-2 days, then on a shelf/table in a dry and well lit area.

Fast forward a week or two or three depending on the time of year, pictured are three cuttings all showing basic coloring on their ends. Colors can range from white, brown, orange, gray to black etc. in areas. This is a not a problem….as long as the ends are DRY and the coloring is not mold etc. If you can’t tell, a quick wipe with a paper towel and rubbing alcohol will help clean it again. Sometimes when they arrive if you purchased online, after being in a dark box for 3-4 days, some surface mold may develop. Just do a quick wipe as noted and allow to dry. If it’s soft, mushy or infected for whatever reason, simply start the cutting over remembering to sterilize w/ each cut. You can go 1/4″ inch, 1/2″, 1″ etc. whatever you need to do to get back to healthy colored cactus.

For this Blog, they are calloused and ready for the next step, potting! Side note question we are often asked, “How long can I wait until I have time to pot my cactus”? You can forget about your cutting for months with no problems, ideally left somewhere out of direct sun, and kept dry. Sometimes though, factors like temps, it’s growing season etc. your cactus cutting can begin growing again from it’s tip which would begin to stretch and bend upwards. Picture shows a tip that bent this way, it will gradually straighten back up.

They can also begin shooting out roots along it’s entire length on the side facing down. This is called planting logs, just laying them on soil horizontally vs vertically. This happens naturally in the wild when they snap and fall down.

Back to potting. Lots of info on soil etc. out there, the main thing is soil that drains well, we use perlite and sand out here, use whatever you can, but stay away from houseplant soil that retains moisture vs soil that drains quickly. Rule of thumb is never to water if soil is wet!

I fill my 1 gallon containers up about halfway with DRY soil. Some people use damp soil, I usually try and go dry, but you can experiment… I place my dried cactus cutting into the container.

And I add 2-3″ of dry soil and usually don’t pack down, just leave it fluffy if possible or just enough to keep it from falling over. I don’t like to go all the way to the top as I have found when I begin watering, the soil will settle and it will leave me w/ approx. 2″ of space for water to collect and then settle down. If soil line is too high, you have to water and wait to make sure your watering reaches the bottom. (I always try and water all the way through the container, it helps the rooting process go deep and stronger vs the roots just sitting on the surface.)

I try not to water for approx. 2 weeks. There are no roots to absorb water and if there are any issues w/ my cutting that I did not catch, it helps lessen any infections settling in. Open wounds and wet soil can increase the chances of infection, fungal problems etc.

I place the newly potted San Pedro(other columnar cacti) in a dry place out of direct sunlight. In this picture they are outside under some Oak trees.

After a few weeks, months, when roots have begun forming and they can take in water etc. I will move to direct sunlight. We grow our cactus all over our 5 plus acres of property, some in full sun, some partial, some completely shaded. Lots of different soil types as well from natural decomposed granite to soil amended w/ mulch etc. Colors can vary from light green to dark green, experiment with yours, find the location you think your cactus is happiest at/or location you like the most, and enjoy.

You are now ready to do this on your own, it’s the easiest way to turn your single San Pedro into an actual cactus patch! Have fun and don’t hesitate to email us w/ any cutting questions!

Cheers

Pruning An Agave Plant

As a part of the care and maintenance of the agave plant you will need to prune the plant according to its needs. This can be seasonal pruning, or pruning to clear off any dead leaves, or diseased areas.

Seasonal Pruning

Before the growth season begins you should spend some time pruning your agave plants. Late Summer or early Fall are good times to prune the plants before the winter weather sets in. Pruning now will push out new growth that will have a chance to establish itself without being damaged by the weather.
You should also prune after the last frost of the Winter. This will encourage new growth after they have been dormant.

Clean up Pruning

There will be times after a growth period when you will need to prune down some of the branches to a more manageable level. If you do not want the plant to get too large, then prune off the top growth. If you want to contain the plant to a certain width, keep pruning the side growth.

Use Strong Shears

The leaves of the agave plant are quite strong and have spines on the tips. To prune them, use strong shears that are sharp to minimize any tearing and injury to yourself.

Is my cactus dying?

The discoloration and shakiness can both be explained by cactus root rot. Cacti have a wide, shallow root system to maximize water collection in their natural habitat. In the constricted space of a pot, over-watering, compacted roots or poor drainage will quickly lead to root rot. Sometimes just the base of the cactus, and not the roots, is affected by water that does not drain quickly enough and is standing around the base of the plant. These are among the most common problems with growing cacti in the home.
You should remove your plant from its pot and check to see the condition of the roots. If some are still white, cut away the darkened,mushy roots and any rotted areas at the base of the cactus with a sterile knife. Allow the plant to dry and heal out of the soil before re-potting in a clean container with fresh cactus potting medium. You can use a folded length of newspaper to protect you and your cactus from hand to spine contact.
If the roots and the base of your cactus are completely soft and brown, you have sadly lost the plant.
For general help with caring for your cactus going forward, refer to the NYBG guide to Cacti Indoors.
Good luck and let us know if we can offer any further help.

Azarius

Introduction

Cacti grow in many parts of the world, especially South America and Africa. There are several different kinds of cacti accommodated by our planet. Cactus plants like to grow in places where little other plants like to grow since most cacti grow in arid regions, people often associate them with deserts. However, only a small part of cacti grow in extremely dry areas.

Cacti have always been popular plants, partly due to the enormous variety of cacti we can find and the little care they require to grow and live. This means that cacti are the ideal plant for any kind of gardener.

Because most cacti need very little care to enjoy a healthy environment, they are extremely easy to keep in and/or outdoors. Due to the great variety of cacti, it can be quite difficult to describe the ideal circumstances for each to grow. They each have their own preferences. However, there are many growing environments that apply entirely or partly to most cacti.

Pots

The size of the pot is very important for the cactus. If the pot is too small it can cause the roots to asphyxiate. The cactus will hardly grow, or growth will stop and eventually the cactus will die. If the pot is too big and it has too much soil it will hold too much water and this can eventually cause the roots to rot.

In general, you can say that the bulbous cacti (i.e. from the Lophophora family) are most comfortable in pots that are just slightly bigger than their roots. The tuberous cacti (i.e. from the Trichocereus family) normally need a bigger pot than the bulbous cacti.

The pots are normally clay/ceramic or plastic. The hobby growers normally choose pots made of clay. These pots allow the cacti to breathe better and the soil dries faster inside. Clay pots are more expensive than the plastic ones.

Make sure the pot has one or more holes in the bottom. Cacti prefer to soak up the water from below rather than from above.

Cactus soil

Good soil mixture can make a big difference for the health of your cactus. However, the choice of the soil mix largely depends on the climate conditions.

Normal pot soil is generally not suitable for most cacti, this soil has the capacity of keeping water for a long time. This is something that horrifies cacti. Garden centres offer special cacti soil. This soil will work just fine for most cacti. However, most hobby cultivators prefer to use mixtures that they have prepared themselves after many years of experience.

Ingredients which are often used in cacti soil mixtures:

  • peat
  • coconut fibre
  • pot soil
  • small gravel
  • perlite
  • pumice stone
  • lime stone

Most mixtures are made of 20-25% organic material and the remainder is an inorganic material. It’s very important that the mix is loose and light. If this is not the case, it will hold too much water, and this can cause the roots to rot. Cacti also need sufficient nutrients and trace elements. Eventually, the soil will be depleted of these nutrients. It is therefore recommended to add a little manure to the mixture once a year to keep a buffer.

Light

The right amount of light is the most difficult part of the maintenance of cacti. Especially if you live in a cold dark country you should make sure that now and then your cactus receives plentiful light. Cacti are naturally used to receiving lots of light. Most cacti can survive with less light, but this will slower their growth and they will never start flowering. During the summer, cacti normally receive more sun light than in the winter. Most cacti actually need just a few hours of full sun light. Don’t forget to always place the (mature) cactus near the window. It is also possible to provide the cactus with artificial light. The fluorescent lamp is an option, as it provides plenty of light. The disadvantages are that these lamps give little warmth, and they have to be placed at a maximum distance of 10-30 cm above the cacti. Another alternative is the halogen lamp. This lamp gives off a lot more heat. HPS (High Pressure Sodium) lights are great, but energy usage is high.

Keep in mind that too much light can cause problems. Should the cactus receive too much light, the side exposed to the sun will lose colour, resulting in burn marks. This can cause permanent scars.

Temperature

It is well known that cacti enjoy the warmth. That is why they grow mostly in the warmest regions of the planet. But even the warmest countries often have cold nights. For that reason, many cacti can withstand colder temperatures. Some cacti are even able to endure frost for a short while, provided they receive plentiful heat and light during the daytime.

Indoors, cacti can generally be kept at room temperature. In the regions where cacti also survive outdoors, it may be better to keep them inside during the winter time.

Watering

The most common death cause for cacti is overwatering.

Our advice, therefore, would be:

Do not over-water your cactus!

Most cacti die because people give them too much water. Most people find it difficult to know when their cactus is in need of water. So the best thing to do is let the soil dry out completely before watering again. A humidity meter can be very useful in this case. When in doubt, it is best not to water your cactus yet.

In summer cacti need more water then in the winter.

General guidelines:

Summer: water your cactus once a week

Winter: water your cactus once to 2 or 3 times during the entire winter period

However, these amounts can vary tremendously depending on the cactus and environment!

Watering from the bottom is preferred. Cacti like to absorb water from bellow where their roots are. Therefore the pot must have one or more holes in the bottom and a dish/saucer underneath it. When you fill the dish with water, the soil will absorb the water from bottom to top, easily reaching the roots of the cactus. Get rid of any water that has not been absorbed within two minutes. Larger cactus plants might take a minute or two extra to soak up the water.

Transplanting

Cacti, and especially their roots, don’t like being repotted. However, some cacti grow really fast. If they live in a too-small pot, the cactus can become root bound. The cactus will stop growing and eventually dies. That’s why they need to be transplanted once in a while to a bigger pot to keep on growing.

Some care is needed when repotting a cactus. It is not just the cactus that can be damaged. The prickly needles are hard not to notice (ouch!) Therefore, always wear thick gloves or a folded cloth to protect your hands when handling a cactus. Be careful!

The best time to transplant cacti is right after the winter period.

Diseases

Most cacti are vulnerable to the same sicknesses and plagues as the normal home and garden plants. Therefore it’s really important to check your cacti regularly for whatever vermin may appear. Also here prevention is better than cure. So make sure you create the right environment where the cactus can grow at its best, but germs and insects stand no chance.

Fungicides and pesticides can quickly eradicate nasty bugs and pests. However, be aware of overdosing of such fungicides and pesticides. Often the cactus will die because of these products. Always carefully follow the instructions printed on the package, always use animal and environment-friendly products.

The most common diseases are:

Rot

  • infestation of roots and bottom of stem by fungi and bacteria
  • recognizable by a dark colouring
  • cactus feels soft/mushy
  • it spreads to the upper part
  • problem: soil mixture not permeable enough and/or too much watering

solution: save what can be saved. = make cuttings from the healthy parts

Frost damage

  • recognizable by parts of the stem getting brown/black and chubby after de-icing
  • can be prevented by enough warmth and ventilation

The most common plagues are:

Mealy bug

  • the most common plague amongst cacti
  • normally white coloured
  • small, oval insects
  • produces a white waxy substance
  • it sits around the roots, stems, leafs and/or young plant sprigs
  • it is a slow-moving insect
  • solution: special insecticide for mealy bug
  • when you notice that a cactus is infected, immediately separate it from the others

Aphids (plant lice)

  • small round/convex insects
  • normally green coloured
  • normally appears in great amounts
  • can cause black fungus
  • solution: insecticide, gauze-flies, ladybugs

Scale insect

  • different types varying from 1 mm to 1 cm
  • different colours varying from white to brown
  • quite uncommon on cacti, and is normally brought in by new plants in the collection
  • remove the insects with your hand or a brush, most pesticides don’t work well enough to get rid of adult scale insects

Trips

  • winged insects smaller than half a millimetre
  • yellow brownish with the shape of a rice grain
  • move fast forward on the plant
  • withdraw food from the plant spreading a bronze to silver colouring on it
  • show up for no reason and often disappear again by themselves
  • easy to fight of with the appropriate products

Multiplying your cacti

Growing from seeds

An easy way to set your first steps in the cultivation of cacti is by growing from seeds. Most cacti seeds germinate quite easily and do not require too much care or a very specific growing environment.

The first step is choosing the soil mixture. There are several different recipes for a proper soil mixture.

A proven and widely used soil mixture consists of:

  • 1/3 pot soil
  • 1/3 peat
  • 1/3 small gravel (1-3 mm)

As upper layer, use sand or gravel (1/2 – 1 cm.).

One of the risks when growing from seeds is the huge amount of bacteria contained in the soil mixture. Especially in the early growing phase, the seeds are very vulnerable to various diseases and plagues. It is therefore important that the soil mixture and the top layer of sand or small gravel are sterilized before the seeds are planted. This sterilization can be done with a pressure-cooker or a microwave. It is preferable to use the pressure-cooker because it delivers better results.

Pressure-cooker: 60 minutes on 15 psi

Microwave: 8 – 10 minutes maximum watt

When the soil mixture has cooled down and the pots (with holes underneath) are filled, cover the upper part with a thin layer of sand or gravel (also previously cooled down). The seeds may now be planted. Do not press the seeds any further in the soil. These very small seeds will not germinate if they are placed too deep in the soil. Spreading them carefully is more than enough. Finally, give the seeds and the soil a good spray with water. The seeds will then sink down a bit all by themselves. It is advisable to use a (light) fungicide at this time to prevent bacterial contamination. Place the pot in a bucket with water for about 5 minutes, so the soil can also absorb the water through the bottom holes.

Now it is time to let the seeds germinate. Keep the pots in an environment that meets the followings requirements:

  • Warmth. Keep the pot with seeds in a warm spot with a (constant) temperature between 20 and 30 °C
  • Light. The seeds need some light to germinate. However be sure to keep them somewhere away from direct sunlight. Seeds and small cacti are very sensitive to (bright) sunlight
  • Humidity. Germinating seeds love a high level of humidity in the air. The ideal percentage of humidity is between the 60 and 90%. To easily reach these levels, keep the seeds in the smallest possible growing space. This means that in the early phases of germination the seeds should be kept in a closed pot or bag.

After 3 to 10 days the seeds should start germinating. From this point on most of the work will be processed by itself. However, make sure the growing environment constantly meets the optimal conditions, to assure a good start to the newborns. After 2 – 3 months, punch a few holes in the bag every two weeks so that the small cacti can slowly get accustomed to the dry (or less humid) air.

After 6 months the cacti are already much bigger and stronger and can be removed from the closed pot or bag.

Cuttings

Growing from a cutting is done by simply cutting off a piece from a cactus and placing it back into the soil. However, wait two to three weeks before replanting. This gives the cutting time to heal the wound created when it was cut off.

The best time for making a cutting is the beginning of the growing season. If you cut a part from the cactus, always use a sharp and sterilized knife. If you don’t sterilize the knife the cutting can suffer from infections.

Afterwards, let the cutting dry well before you place it again in the soil to grow. This drying period can vary per cactus from a few days to a few weeks. To let the cutting dry really well it is best to keep it in a warm spot with some air circulation.

A lot of cacti from which a cut was extracted will develop new shoots where the cutting was made. After a while, you can also cut these new shoots to use as cuttings.

Cactus Pruning Info: How And When To Prune A Cactus Plant

Cactus are low maintenance plants that generally thrive with neglect and do not require a lot of pampering. It might surprise you to find that cacti can and do need to be pruned now and then. Cactus pruning is not always necessary and when to prune a cactus plant will depend upon why you are trimming it. A few notes on how to cut back a cactus for purposes of propagation, rejuvenation and structural integrity will send you on the road to cleaning up your succulents properly.

Can You Trim a Cactus?

New succulent growers may ask, “Can you trim a cactus?” Most cacti really don’t need any form of shaping unless they have a great huge limb that looks ready to tip the plant over. The major reasons for trimming cactus are to remove parts to root for new plants, remove offsets or pups for the same reason, reinvigorate a plant that has gotten too tall or too leggy, and to take off damaged material.

Cacti come in a wide range of forms. Cactus pruning can enhance these forms while preventing overcrowding, which can increase the chance of disease, mildew and unhealthy plants.

  • The Opuntias, Crassula and Senecios have pads that serve as leaves and these are easy to remove and can be used to start new plants.
  • Columnar plants, like totem pole cacti or organ pipe cacti, may simply get too tall or spindly and require a judicious beheading to force branching or simply thicker stems.
  • Still other succulents in the family will produce flower stalks which are persistent and become ugly when dead. Removal of these will restore the beauty of the plant.

Trimming cactus has a variety of purposes, but the good news is that you can use many of the parts you remove to start new plants.

How to Cut Back a Cactus

The “how” of cutting back a cactus answers like a bad joke. The simple answer is, very carefully. Most cacti have some type of spine or prickle which can be painful to encounter. Use thick gloves and wear long pants and sleeves for the bigger garden specimens.

The tool will depend upon the size of the plant, but most will succumb to pruners. Only the largest will require a saw. As with all pruning, make sure the tool used is sharp and clean to avoid injuring the plant and decrease the chance of disease.

Remove limbs at the branch point but be careful not to cut into the main stem. Pads or leaves may just snap off or you can use pruners to remove them.

For a big job like cutting back a columnar specimen, use a saw and remove the main trunk at the point at which you would like to see branching or at the height you require the plant. Try to remove the stem at a growth point.

Plants like agave will need the old leaves removed to preserve the appearance. Cut them away at the base of the plant with shears.

What to Do With Pruned Off Parts

Now for the fun part. Almost all the material you remove is salvageable except for diseased or dead stems and leaves.

  • Pads will root if laid on top of soil and develop into a new plant of the same species.
  • Cut stems and trunks should be allowed to callus at the end for several days and then can be planted to create new cactus.
  • Any offsets or pups that you cut away from the base of a specimen are new plants in their own right and should be potted up immediately.
  • Dead flower stalks and leaves are compost, but some varieties of cactus produce leaves on the flower stem which can be treated the same way as the pads of other species. Most cactus parts will start rooting within a month.

Once you restore your initial cactus to its glory, you will have the pleasure of making more of the spectacular plant and can increase your collection or give them away to family and friends.

Gardening FAQ

Pencil cactus (Euphorbia tirucalli in the Euphorbiaceae family) is a common houseplant and a fast grower. Mature plants can grow up to 25 feet tall and often have a “pine tree” sort of appearance. Pruning them is fairly easy and should not harm the plant. Here are some tips on pruning.

· Protect your eyes, skin and clothes from the white latex-like sap. This sap can cause skin and eye irritation which can sometimes be severe. It will also stain your clothes and become black when it dries. Also, because of this sap, these plants are not good for composting.

· Remove any dead, damaged or diseased branches. This will both tidy up the plant and promote new growth.

· Determine the shape and height you would like for your plant. Then use pruners or sharp, heavy scissors to shape the plant as desired by cutting off the branches above a node. When pruning, cut to the base of each branch at its point of origin. Do not leave a stub sticking out of the stem.

· If desired you can also thin the plant further by removing vertical branches that are thin and weak or too numerous. Again, cut these branches at their point of origin. Thinning also allows more air circulation through and around the plant, thus improving its overall health.

· Carefully throw out the parts of the plant you removed. Alternatively, give them away to friends who may want one of their own. Just be sure they wait a few days to let the wound dry and callus over before planting the bottom few inches of the cuttings in soil.

The best time to prune is in the spring when light and temperature have increased and the plant has started its active growing period. Be careful not to remove too many branches at one time because that could shock the plant. As a general rule, no more than 1/3 of the plant should be removed during any given pruning. Also remember that once something is cut off, you can’t stick it back on. So you may want to prune lightly and then see if that meets your needs. If not, then prune some more until you get the desired result.

For tips on a variety of gardening topics, see our Plant Information Guides.
– Courtesy of NYBG Plant Information Service

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