Palms   Cold Hardy Palms

Cultivation Table of Contents Planting Cold Hardy Palms Maintenance of Cold Hardy Palms Moisture / Water Fertilizer Old Inflorescences & Dead Leaves Winter Protection Winter Damage Pests & Diseases Germinating Seeds Palms as Weeds   Planting Cold Hardy Palms Create an extensive area of well-amended soil in the area where you intend to plant the palm. Mix in lots of compost and a well-balanced slow release 3, 1, 3 ratio fertilizer. You want the largest area of prepared soil as you can manage so that the root system of your palm is not curtailed. Prepare new plant beds in fall or winter so that the soil ingredients have time to cook by the time spring planting arrives. Plant AFTER last-frost in spring but before mid-summer. You want the palm to have plenty of new roots established and to be over any transplant shock before it has to endure winter shock. Plant the largest palm you can afford , gallon-size being the smallest recommended, five-gallon being better, especially with trunk-forming palms. If you purchase quart or pint-sized palms (as they are often available on the Internet) it is advisable to grow them up to a larger size before planting out unless they are rated one zone hardier than your climate. If you apply fertilizer, use a slow- release 3, 1, 3 ratio formula in early spring and perhaps again in early summer, but DO NOT fertilize your palms any later than that. You want your palms growth to be slowing down with the season, not surging along when frost arrives. Site your palm in such a way as to mimic its natural habitat as much as possible. It is dangerous to place palms where they will receive a lot of shade in winter, even if they are hardy to 10F (-23C) . Even the cold-hardiest palms can be damaged or killed by an extended freeze. Their hardiness is to cold snaps, not prolonged freeze. Maintenance of Cold Hardy Palms If you follow the planting advice and only plant palms rated for your USDA climate zone, then maintenance of your palms will be minimized. If you push the limits and try growing palms rated beyond your zone, then extra winter care will be needed. I recommend NOT pushing the limits because gardening is enough work as it is. I want you to enjoy your palms, not worry about them. If you follow the planting advice, then the most important maintenance issues are: providing correct moisture regime; correct nutrient regime; and removal of old inflorescences and dead leaves. Moisture / Water Adequate moisture during the growing season is perhaps the most important factor contributing to robust growth and health of a palm (assuming you have followed the planting advice given). Except for species native to arid climates, an inch of water a week during the growing season is a good rule of thumb. That also happens to be the rule of thumb for lawns - so when your lawn is drying out, so are your palms. Providing adequate moisture can be as complicated and expensive as installing an irrigation system, or easy as dragging around the garden hose. Suit yourself. Locate species from arid climates in well-drained soils and landscape positions where they are less likely to develop problems from over-watering. If they like sun, give them an open south-facing position in the landscape. Fertilizer There are reports that it is advantageous to grow marginally cold hardy palms hard by which is meant without fertilizer. This seems also to be true for cold hardy palms during severe winters. If you consider that cold hardy palms grow naturally and quite well in their native habitat without fertilizer, the act of applying fertilizer seems superfluous (except in impoverished soils). Whatever the case, NEVER over-fertilize and ALWAYS provide a proper watering regime. A 3, 1, 3 ratio formula (N, P, K) is recommended (where N = nitrogen, P = phosphorous, and K = potassium). I use a slow-release rose fertilizer 16, 5, 13 because it is readily available and approximates the ratio needed. Too much fertilizer may be detrimental to palms. Dont over do it. Only apply fertilizer in early spring or early summer. A palms growth needs to be slowing down as fall and winter approach. Slow-release fertilizers with micronutrients are safest to guard against chemical burn. Nutrient deficiency is only likely in very sandy soils, but should be resolved with typical slow-release fertilizer with micronutrients, or by water-soluble fertilizer. Not everyone uses fertilizer. Impressive results have been demonstrated with root hormones and a proper watering regime. A product called Superthrive provides an artificial rooting hormone that has been shown to be effective. Some growers avow by kelp-derived products that naturally have plant hormones. If you use fertilizers or plant hormones, more is not better. Follow the label cautions and directions. Old Inflorescences & Dead Leaves The removal of old inflorescences or dead leaves is really only done to maintain the look of the palm and control reseeding. If you cut off the inflorescences too soon, the plant may form new ones, making more work for you. Some palms can reseed generously, which is a characteristic of the Sabal species. If you dont want to bother with unexpected seedlings throughout your landscape, remove the inflorescence after the fruit has set but before it ripens. The effect of removing dead leaves is not purely esthetics they may be very important in shielding the trunk and growing bud from severe cold. Someone may think that removing dead leaves improves the look of the palm, but what good is that if the palm dies during a cold winter because of the act? Now that you know the possible repercussions, suit yourself - and dont blame me. Winter Protection If you are not pushing the limits and are only planting cold hardy palms rated for your USDA climate zone, then little or no winter protection of your palms will be needed except possibly during their first winter in the ground. However, if a record low is predicted, you may want to protect any palms that might be marginally cold hardy for your area. You want to protect the palm from two things: moisture around the growing point (bud/spear), and the cold. There are many ways to protect palms, depending on their size. Two things need protection, the growing bud and the trunk. Small palms are easiest to deal with because the whole palm can be covered, but palms with large trunks or giant spreads of leaves are difficult. Partially filled water bottles buffer temperature changes. Electric heating pads are available that can be wrapped around the trunk, but some people wrap the trunk in Christmas lights and wrap the whole thing in landscape fabric. Anyhow, the garden can soon look rather unpleasant, and it is a lot of work putting up and taking down the protective devices; good reason to use only palms suited to your USDA zone. Winter Damage Every year there may be some winter damage to the leaves of all but the hardiest of palms for your climate zone. Do not lose heart. If a few or many leaves get brown spots, or if young, emerging leaves (called spears) turn brown and later pull out with a gentle tug, all is not lost. Young windmill palms are prone to having their spears die in winter, but this is not the end of the world, or the palm. If the spear turns brown, apply a fungicide. The spear(s) may pull out, but new spears should emerge in late May. The fungicide I have used is one designed for aquariums. It is not supposed to harm aquatic plants, and it has not harmed my windmill palms. If all the leaves of your palm turn brown, it is not a good sign but be patient. If no new growth appears by June, the palm has probably had it. If the palm is a type that forms suckers/offsets, wait to see if these appear. Pests & Diseases Perhaps the most destructive pests of palms are voles. Voles should not be confused with moles. Although both moles and voles burrow through the soil, moles are carnivores that eat worms, beetle grubs and beetles, while voles are herbivores and eat roots, tubers, corms, and bulbs. A hungry mole (they are always hungry!) may even eat a vole. Various traps and poisons can be used to control voles. Scale insects can be the bane of Sabal palms, but Trachycarpus palms seem entirely immune and devoid of scale. Scale insects appear as small gray, white, or brown scales, usually on the underside of the leaf and along the stem. They can be controlled with horticultural oils, which suffocate the insects. Horticultural oils should not be applied when leaf temperatures near 90F (32C), as this may result in leaf damage. Always read label warnings, adhere to self-protective guidelines, and follow label instructions even if it is just for horticultural oil. Seed beetles are Bruchellid beetles. The female lays her eggs, one per seed, in the developing fruit of palms. The adults are rarely seen, but their presence is indicated when the larvae are found in the palm seeds. Control is a matter of destroying infected seeds. Normally the seed beetles are not so abundant that control is necessary. Spider mites are a common bane of indoor palms and palm seedlings. Infestations of spider mites are controlled with miticides. Lethal yellowing is a viral disease that has devastated coconut palms, but is transmissible to other palms. There is concern in subtropical regions (such as Florida) that an occasional Trachycarpus palm may harbor the virus without symptoms. But in temperate climates this is not a problem simply because there are no tropical palms to infect. It does remind us, however, of the importance of only transporting clean seed and disease free plants. Always inspect palms to be purchased for any evidence of disease or ailment. Only introduce healthy palms into your landscape or collection. Germinating Seeds If you have the time, or nursery specimens are unavailable or too costly, then raising palms from seed can be a very rewarding experience. Obtain fresh seed! Viability and germination rate decrease with age. Be certain your seeds are fresh. Time to germination can vary from a few weeks to a few years depending on the species and seed quality. Notoriously quick germinators are Nannorrhops ritchiana , Sabal minor , Trachycarpus fortunei , and Washingtonia filifera , by which is meant within a month or so, but may be as long as six months or more. Generally the less fresh the seed, the longer it will take to germinate. Float-test your seeds for viability; if some float and some sink, reject the floaters. If you are uncertain, isolate the floaters and attempt to germinate them separately. Clean the flesh off the seeds. Removing the flesh is especially important if you intend to mail or transport seed. Removing the fruit flesh can be done manually or by fermentation. If the seed is small, in nature it probably is eaten and distributed by birds or mammals whose digestive systems would remove the fruit flesh and clean the seed. To ferment, place seed in a wide-mouthed container with just enough water to submerge the seeds. Place the mixture in a warm location for a week or so; empty the water; thoroughly scrub and rinse the seeds as clean as possible; repeat for another week if necessary. This is best done outside or somewhere that people will not be offended by the odor and plethora of midges, gnats, and flies that will be attracted to the brewing concoction. I have found a 1/4inch wire mesh screen very useful. I simply place the screen over an empty bucket, put a heaping handful of fermented palm fruits on the screen, rub them vigorously with latex-gloved hands against the screen, then rinse the mess. After a few passes the seeds are quite clean. In this manner I processed roughly 8000 Sabal palmetto seeds in two hours. Palmetto seeds are only slightly larger than the mesh size. Larger seeds are easier to process. A nurseryman states that he merely plants his seeds after fermenting them, and that theres no need to bother about removing any remaining fruit flesh. If you have thousands of fresh seeds to process, this may do. However, if you have just a few rare seeds, youd be wise to give them every chance they can get and clean off the fruit flesh. Disinfect the seeds. This is important for mail-order seed if it arrives with the fruit flesh intact and harboring fungi. It is also a form of insurance if you are working with very little seed, or seed that is rare or expensive. If your seed is very fresh from a local source, and clean, this step probably is not needed. Disinfecting solutions can bleach your carpet and fabric and irritate your skin and mucous membranes, so wear eye protection and gloves, and work in a well-ventilated room or outdoors. Create a 10% bleach solution (one part bleach with ten parts water). Dip the seeds into the solution, and rinse thoroughly with tap water. Alternatively a 5% hydrogen peroxide solution can be used (one part hydrogen peroxide with 20 parts water). Do not overexpose the seeds to disinfectant as it may harm them. If the seeds are not used immediately, allow them to dry to the touch, then store them in a labeled, sealed plastic bag, or plastic ware, in a cool environment. If they are too moist, fungi or bacteria may grow and damage the seed. Seeds of palms from temperate regions may require a cold stratification at 40F (4C) for six-weeks to improve germination. Cold stratification is simple. Place a portion of clean and disinfected seeds in barely moist medium in a sealed plastic container or bag, then refrigerate for six weeks. DO NOT ALLOW THEM TO FREEZE. It helps to place the remove by date on the container so you know when to take the seeds out for germination. Since temperate palms produce fruit in the autumn, it is easy enough to store the cleaned seed in an unheated garage during winter. When the garage heats up in spring and summer, germination will commence. Select a germination method and medium. I recommend old plastic water bottles with the top cut off and a few holes cut into the bottom for drainage. Seeds of palms from arid regions should be germinated in a perlite mix, while seeds of moisture loving palms can be started in potting soil or commercial garden soil. Fill the modified water bottle with medium, push a seed into the center and cover to a depth about 2X the seed diameter. Maintain moisture. Other methods include placing seeds in a large, broad-rimmed community pot with a growing medium, or in a large re-sealable clear plastic bag with moist perlite. In the latter case it is crucial to check the bag frequently and remove seedlings before their roots become hopelessly entangled. I have had great success germinating fresh Sabal palmetto seed simply by sewing it in rows in a garden bed. I did this in late winter, and by July had seedlings sprouting thick as corn. Date and label the seed containers. Cover with loose-fitting plastic and place in a warm site, 80F (27C) or so. Too high a heat can harm seeds. Check weekly for seedlings. I place the seed containers in my garage. In winter they get exposed to cold (but not freezing), which is required by temperate species. In summer the garage warms up and the seeds germinate. When either the seed leaf has grown substantially or the taproot begins to show through the bottom of the cell, transfer seedlings to a larger pot. Place the seedling in filtered sun or part-shade or under a good grow-lite in a warm location at least 70F (21C). Fertilizer will speed the growth of seedlings once they have a well-developed seed leaf and adequate light. Keep records of your methods and successes or failures to improve your future results. Palms as Weeds Folks, this is simple. If you dont want stray seedlings from a plant, then dont let its fruit ripen. Thats any plant, including palms. With many plants, if you remove the inflorescences too soon they will grow new ones. It is better to wait until the fruit is set, but not ripe, and remove it. Palms, even the very fecund ones, are rarely weedy. There may be a seedling here and there, but not a rampant swath as you may get from Purple Loosestrife, Kudzu, English Ivy, or Japanese Blood Grass for heavens sake. And weeds are hard to kill. If you want to kill a palm, on the other hand, you will likely succeed your first try. Very few palms regenerate from their roots. Once chopped down they are gone. A notable exception is Serenoa repens , which can regenerate from its roots - an important trait to have when your habitat is frequently razed by fires. Personally, I hope all my palms set fruit every year. That way Ill have seed and plants to share with friends.