(Editor's Note: This article was originally published on May 23, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
Though palms are trees, because their root structure differs from most dicot trees there may be some different strategies to planting palms than one might use to plant most other trees. This short article is a discussion of some various techniques used by palm specialists and growers about the country.
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