"The Wise Gardener!"
The Sensual Pulse of the Tropics!


Let's "Re-visit" Palms & Citrus in Zone 8 & 9:
The Gulf Coast CAN Again, Look More Sub-tropical!

troplogo.gif (7491 bytes)Gardening Friends, Do You Remember When Almost Everyone Grew Citrus In Their Yards, and had many more palms than are seen NOW, on the GULF COAST? Cold snaps made you say, "NO MORE "sub-tropical plants"!"   Well, let's Take A Look, AGAIN, At These Desirable Dooryard Plants In Zones 8 & 9!!

Pensacola, Mobile, Biloxi-Gulfport & New Orleans once had a decidedly more "tropical" look that has largely been replaced by a more "Southern", but conservative Zone 7, or perhaps, 8A landscape look!  Too bad, really!

It's easy to understand why conservatism has reigned over the last 15 to 20 years!  The cold "snaps" of yore, have been MORE regular visitors, it seems, now they occur, almost all of January and February, and the back half of December, and first half of March!  This yearly frustration, of dead or, at least very unsightly "browned out" frozen foliage, all winter has made us just too unwilling to "try" something a bit more Gulf Coast-like!

[Windmill Palm  Picture]But "miracles" of hybridization are advancing the quest for a "tropical looking" plant, be it palm, hibiscus, or citrus, yet being a totally hardy and "winter-good-looking" plant!  Can it be done?  "Yes!!"

Research and hybridization for plant cold tolerance, has been on-going, in places like the University of Florida, Texas A & M University, Louisiana State University, and other land-grant SE USA colleges and universities.  Rather promising cold-hardy palms & citrus have been developed, and have endured at least five years of weather testing, and are NOW, finally in enough "production" to be just about ready to show-up at area garden centres! 

Some have proved "better than others", obviously; it's doubtful that a coconut palm will be seen in most of our lifetimes, growing at Gulf Shores, AL, but NOT totally inconceivable that coconuts MAY some day grow all the way to Zone 9 A, or possibly 8 B!!   The thought of that is rather astounding, friends!

For now, let's look at the lengthening list of perfectly hardy Palms and Citrus that need to make their re-appearance onto The Gulf Coast's homeowners' properties!

Hardy Palms:

Sabal minor and Nannorrhops ritchiana are also very hardy. Both survive 0° F once established. (Protect for the first two years in zone 7.) Sabal minor is native to the southern United States as far north as eastern central North Carolina. It likes heat. Nannorrhops is from Afghanistan and Pakistan. It is rare in cultivation. It may be as hardy as the needle palm, but further testing is needed.

Trachycarpus martianus has a smooth trunk, but is less robust and harder to grow. Trachycarpus takil has been recently rediscovered in Asia, and it is unclear whether it is really a distinct species.T. nanus is a trunkless palm from China, while T. caespitosus is an almost unknown clumping variety. T. wagneranus (right) has smaller, stiffer leaves than most plants labeled "T. fortunei," but many consider it to be a variety of T. fortunei. Other varieties have been recently discovered, and will be featured here.

All three palms listed so far share one important characteristic: They are basically trunkless. The hardiest arborescent (trunking) palm is the Windmill Palm -  Trachycarpus fortunei (shown). These are grown as far north as parts of British Columbia in Canada. They have a fuzzy trunk which can grow twenty feet tall. They do not need a hot climate, and seem to thrive in cool, moist weather. Windmill palms are not a good choice for hot, dry areas with sandy soil. In the winter, they lose their leaves when the temperature drops below +10° F for extended periods, and they can be killed below +5° F.  Click here for a  picture of Trachycarpus in Oregon . Other species of Trachycarpus are rarer.

[Sabal palmetto  Pic]Sabal palmetto (Sabal palm, Cabbage palm) is the state tree of Florida and South Carolina. It has been known to survive between zero and +5° F when well-established. It cannot survive these temperatures on a regular basis, and is probably best rated as zone 8a. It is a large fan palm which takes many years to form a trunk. It can be found in the wild as far north as Bald Head Island, North Carolina, near Wilmington.

It can be tricky to grow in cooler areas, and doesn't thrive very far north of its native range. Other relatively hardy sabals includeS. etonia - a trunkless palm from the sand hills of Florida andS. mexicana(S. texana) - similar to S. palmetto with stiffer leaves. Some argue that it is slightly hardier.

Butia capitata (jelly palm, pindo palm - left) is native to South America, but used throughout the colder regions of the southern US (zone 8a) because it is the only relatively hardy feather-leaved palm. It is often killed below 10°F.

Serenoa repens (Saw palmetto - below) is a spreading, bushy palm native to the southeastern United States and Mexico. Tourists traveling south on I-95 to Florida usually spy this palmetto first, as an underbrush plant. It seems to be slightly less hardy (zone 8b) than Sabal palmetto. Extract from its berries is used for a prostate remedy.

This palm is just beginning to become available in quantity. For many years it was not cultivated because it is considered a weedy pest in much of its native habitat. The blue form from Florida is especially prized for landscape use.Chamaerops humilis (European fan palm/Mediterranean fan palm) is quite hardy in areas which have a dry climate. It is usually rated as a "zone 8" palm.

In areas with wet winter soil (like the eastern U.S. and the Pacific Northwest) it seems to be less hardy. Planting this palm in a well-drained bed (such as a bed prepared for a cactus garden) may help it survive in these areas.

Washingtonia robusta, Washingtonia filifera, and Brahea armata are western desert palms which are fairly hardy in their native environment (zone 8, zone 9a). The background graphic for this page is a Washingtonia robusta.  They seem to be less hardy in wetter areas. Livistona chinesis andLivistona australis are usually rated as USDA zone 9a. They sometimes survive in colder areas if they are planted in a protected micro-climate and wrapped every winter. Trithrinax acanthocoma and its relatives are probably zone 8b-9a palms. They are spiny palms, native to South America and rare in cultivation.

Phoenix canariensis (Right) is a large date palm which can grow in zone 8b areas. This palm loses its leaves in prolonged periods below 20° F. It is grown in the western U.S. as far north as the southwestern corner of Oregon. Jubaea chilensis is a massive palm from Chile. It is slow-growing and difficult to cultivate, but appears to be hardy to zone 8b, possibly colder. 

The USDA updated the zone maps several years ago based on data from the previous few years. Many people have argued the new zones were based on too short a period of time, and that the zones are now much too conservative . Tallahassee Florida moved from zone 9 to zone 8, for example, and Wilmington, North Carolina moved from zone 8b to zone 7b based largely on a single extremely cold winter. Your property may also have warm microclimates which will help a palm survive. 

Microclimates are climatic variations that occur in small areas. Factors that create microclimates include slope, exposure to sun, proximity to bodies of water, prevailing wind, structures, dryer and oven vents (which allow warm air to escape from your house in the winter) and other plants. An excellent microclimate for growing borderline palms is the south wall of the house . A palm planted against the south wall of your house will survive several more degrees of cold than a palm planted in an exposed area in the middle of your yard.

If you are planting palms which are not reliably hardy in your area, you may want to plant them in clumps. This makes them easier to protect, and you should expect that some of them will probably die. A clump of five small palms may grow into a nice medium clump of three palms in a few years.  Plant palms that are as large as you can afford. Mail order palms tend to be very small. I have found that I have better success if I purchase only in the spring.

I immediately plant them into a larger pot, feed them well, and leave them on my deck for the summer. I bring them inside for the first winter....either into my basement under plant lights or into the garage. They need less light if they are in a relatively cold area like an attached garage. Potted plants are much less hardy than plants in the ground, however, and care should be taken to keep the roots from freezing.

An excellent quarterly publication about hardy palms, The Hardy Palm International , is published by the Pacific Northwest Palm and Exotic Plant Society . They also have tips on hardy bananas (such as Musa basjoo). $20.00 US or $25 Canadian brings you a year of issues, published on time.

Most hardy palm growers recommend protecting the palm from the climate for at least the first two years that it is in the ground. The palm should be mulched with a deep layer of fall leaves or other material. The palm can then be wrapped in burlap, bubble plastic, a spun landscape material such as "remay" or "garden blanket," or even an old sheet or blanket. If you use a non-porous material such as plastic, it is best if air space is left between the palm and the material. This air space may not be needed if you only protect the palm during cold spells.

Another technique involves hanging an electric light bulb near the emerging leaf spear on very cold nights. This is often helpful in very large palms, but it may not be sufficient during the first two years.

Small palms can be protected with "wall-o-water" plant protectors. Additional solar mass can be provided by a plastic milk jug filled with colored water and placed inside the wall-o-water.
 
Die-hard experimental gardeners can gain at least full hardiness zone (ten degrees) by building a chicken wire cage around the palm, filling the cage with dry leaves, and wrapping the filled cage with plastic.


Citrus Species:

As it is very attractive to have citrus plants in the garden - who would not desire to have a mandarin tree in his own garden - it is my passion to cultivate and select especially those citrus plants which are frost-resistant and can cope with our climate.

Thus our target is to select various decorative citrus hybrids with the following characteristics:

Sufficient cold-hardiness, early fruit ripening and acceptable fruit quality - positioned at slightly protected locations all over Germany. If possible the hybrids should be monofoliate and their appearance should be similar to that of ordinary types of citrus cultivation.
For this purpose there are only a few types of citrus that can be used as parents for breeding purpose, also some of them do not have functional pollen, others are not able to develop zygotic seeds.

As in addition the gene-pool of frost-resistant hybrides in Europe is very limited, it is not that easy to get sufficient material for cultivation. Thus first I had to take material from the Citrus Research Center in Florida (USA-United Stats Department of Agriculture) because they have done cultivations of frost resistant plants already since 1900 in order to correspond with the frequently appearing short-term frosts up to -12 degrees centigrade.

Luckily the Research Center put a lot of seeds at my disposal for selections. However, plants withstanding -12 C are not automatically hard enough to bear - 20 C or even colder, but already in this winter some of them have been very promising.

In order to get quick results of young seedlings they will be grafted on to a Poncirus trifoliata rootstock - the frost hardiest, leave shedding, genuine citrus in order to improve growth.

The most successful ones will be added as intermediate grafting on to a Satsuma in order to reach earlier blossom and fruits.
 

Paul, "The Wise Gardener!"

*  TropicRiverWoods.Com * Botanical Gardens * Contact Us!Best Palms' Links!   *  

Island-Style Garden Decorating * Delicious Tropic Recipes! The Tropical Bird-of-Paradise Flower *  

*  Gardeners' Encyclopaedia * National Parks * Desert & Xeric Landscapes * Tropic Travel Destinations  *

  *  Botanical Web Links * Horticultural Societies *  Paul, The Palm Doctor!  *  Take Me HOME!  *

*