Palms in Containers

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Palms In Containers by Phil Bergman

All palm enthusiasts will grow plants in containers. This article concentrates on information about growing palms in containers. Also discussed are plant repotting recommendations, potting soil mixtures and cultural requirements. Find a solution for watering, fertilizing, sun/shade, cold protection and pruning problems.

Anyone interested in growing palms must have some familiarity with growing palms in containers. For a seedling to get large enough to be introduced into the garden, it must initially be grown in a container. Even the hobbyist should utilize containers in his home nursery as he accumulates palms for future plantings. Container culture is the mainstay of commercial palm nurseries.

Plastic pots with UV stabilizer manufactured into the plastic
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Types and Sizes of Containers
The first consideration is what type of container to use. The industry standard is now a black plastic pot with UV stabilizer manufactured into the plastic. Alternatives include plastic grow sacks, clay pots, ceramic pots, or even containers made of recycled paper material that can be planted directly into the ground. Pots come in many shapes and sizes. They can be large enough to grow mature towering specimens. For extremely large plants, wooden boxes are often utilized. Actual shapes, sizes, and designs vary around the world. In the United States they are typically sized according to inches or gallons. Most other countries size their containers according to volume in liters or centimeter diameter and depth. Some areas are utilizing square pot designs that conserve space on growing benches. It is imperative that any pots used have ample drainage holes extending to the bottom of the container. Grow sacks offer the advantage of being more affordable, but do not last as long need stabilization to avoid falling over. Clay pots are attractive but need more frequent watering and break easily. One must utilize what is available and affordable in your area. A container must give ample soil volume for growth and weight for stability. In general, palms prefer deep pots to shallow ones. One would start a seedling in a small pot and repot it over the seasons in progressively larger containers until it is of sufficient size to plant in the garden.

Transplanting a Palm
A new seedling would be grown in a small container, typically ten to twenty centimeters in depth. In one to two years this seedling needs to be stepped up into a somewhat larger container. A palm can usually grow well in the same container for one to two years before transplanting into a larger container is needed. Greenhouse plants require more frequent repotting. The rate of growth and need for repotting is also dependent on the species one is growing. A general rule is that you repot upwards when the plants roots are coming out the bottom of your container, when the soil is showing signs of breakdown of its organic components (soil becomes sticky and dense), or when the plant is just too big and unstable for the container. When a plant has been left in its container too long (oversized), it is top heavy and blows over easily; more importantly, its roots are forming a circular swirling mass in the bottom of the container. It is best to repot the plant before it gets to this point or you may get future stunting of growth.

Most growers can look at a plant and tell that its time to repot. This comes with experience. A root ball should come out with gentle tapping and en bloc. If the dirt merely falls away from all the roots, the plant wasnt ready to be stepped up. If there is nothing but white roots and no soil, youve waited too long. When repotting into a larger pot, you should give ample new potting mix below the old root ball, at least ten centimeters. I mix in a small amount of slow release fertilizer or blood meal into the potting medium in the bottom of the new pot. Never put fertilizer directly in contact with the exposed roots when repotting. Next place the root ball into the container carefully, taking care not to break it apart. Teasing or separating the roots during repotting is not necessary. Next vibrate or shake the pot to encourage the new soil to enter into the root crevices. Then tamp the soil down adequately around the old root ball, taking care not to cause a direct blow to the roots. Add additional soil to make up for the lost space through soil compression and settling. One should leave about three to five cm of watering space above the soil line. Promptly water the repotted palm. I find that a triple watering (fill the pot to the top with water, allow to drain down to the surface, and repeat two more times) is adequate for small to medium sized palms. Larger pots may need four or five applications of water to adequately saturate the soil. If adequate, you should see water trickling out the bottom of the pot.

Outdoor repotting is best performed in the spring or early summer, a time when the plant and its roots can grow optimally. Seedlings and smaller plants may benefit from an antitranspirant (antidessicant) spray after repotting. Most seedlings want to be in filtered light when young, especially after being repotted. If they require sun, acclimate them gradually after repotting. Be aware that some palms such as Dypsis decipeins, Bismarkia nobilis, and most Brahea are known for setbacks after repotting, most likely secondary to disturbing the roots. Root damage is probably the number one cause of mortality during repotting.

Overgrown rootball on a two gallon palm.
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Blood Meal.
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Sand, Grit No. 12
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Peat moss
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orchid bark, small
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Perlite, No.3
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Potting Soil
There are as many potting mixes as there are growers. No single mix is ideal for all growers and all localities. A grower has to use what is available to him. An ideal soil will offer a substrate for the roots to stabilize, provide a source of water and oxygen, and offer nutrients for growth. Good drainage is also desirable for most species. One would like to see a universal potting soil, but in reality there is no such thing. We all tend to utilize one mix with which we have success and then find others having success with an altogether different mix. In surveying many growers in Southern California, I found the soil component common to most growers mixes was coarse sand; otherwise they were as different as night and day. Most growers also used peat moss and perlite. Mixes varied from quite complicated formulas to something as simple as one half peat moss, one half perlite. This spectrum of mixes utilized is probably a commentary that palms will survive in many types of soil.

Knowing that the reader would like to read at least one recipe, I will give one below that has worked for me. I utilize a mixture of coarse sand (#12), fir bark (1/8 to inch), redwood shavings, coarse peat moss, perlite (#2), pumice (ground lava foam), and sometimes a small amount of topsoil. This makes a rather acidic mix, so I add one to two pounds of dolomite lime per yard of mix and about one pound of slow release fertilizer with microelements per yard. This preparation gives a mix with a pH of approximately 6.5. For seedlings I lighten the above mix with extra perlite, peat moss, and redwood shavings. If a mix repels water on first watering (a high concentration of peat moss), you can use a wetting agent. Also remember that high peat moss mixes when allowed to dry out severely actually contract and become next to impossible to wet again. Most growers do not sterilize their mix because of cost concerns. In summary, experiment with whats available in your locality and get advice from experienced growers and ask whats worked well for them.

Remember that any mix must offer support for the plant and simultaneously good drainage.

The lighter the mix, the less it literally weighs and the greater the drainage. The heavier the mix, the more it weighs and the slower the drainage. Drainage is increased by adding perlite, peat moss, pumice, or coarse wood chips. Topsoil, decomposed granite and fine sand slow drainage. Larger specimens and arid loving species tend to prefer the heavy mix. Seedlings and tropical species like a lighter mix. The density of a mix is best appreciated by feeling it with your hands or actually lifting a container with the mix to feel the weight. Most commercial potting soils are considered light mixes. It is not recommended to recycle old mixes, regardless of the composition.

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Palm potting soil.
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Palm seedling mix (different than large palm mix)
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pumice
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