The 2010 Winter Survival Guide

Bill Finch By Bill Finch Press-Register
on January 08, 2010 at 4:14 AM, updated January 14, 2010 at 1:11 PM

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Ah, the garden is redolent with the odor of a really cold Gulf Coast winter, a disconcerting mix of green and sour, like cut grass that’s been piled up to rot. The garden-eating pumpkin vine has been reduced to watery bones, as if it had been boiled all night long. The leaves of the bamboo palm that leaned too far from the eaves are spotted gray. The banana looks bomb-blasted. This will be one of those winters, I expect, that reminds gardeners of our unusual niche in the world’s climate zones. The persistent warmth of the Gulf inspires tropical delusions for months, and sometimes years, on end, until a January day like this one reminds us we’re on the edge of a polar continent. By the time you read this, we may have already set record lows.

Don’t get too dramatic about it: It won’t have been the coldest weather the Gulf Coast has experienced by a long shot. But the worst may not be over, because this is also shaping up to be one of the longest runs of continuously cold weather we’ve seen in a couple of decades. In a more typical Mobile winter, a cold front buzz-saws its way through in the middle of the night, sending temperatures down into the lower or mid-20s for two or three hours, just long enough to toast the leaves of the most tender tropical plants.

But often as not, the temperature will quickly rise the next morning into the 50s or 60s, and the next few nights might even seem balmy.

Our banana leaves may be blackened, but the cold never really has the time to penetrate into the heart of the banana stalk, where it can do real damage.

More significantly, the cold is gone before it can sink deeply into the ground, where it can wreak havoc on roots and destroy the entire plant.

This cold spell is proving to be a cruel contrast to the winter weather we enjoyed through much of the first decade of this century. It reminds me very much of the El Nino winters we experienced in the early to mid-90s.

Temperatures in the teens are tough enough, but the trouble for the garden was that temperatures continued to drop well below freezing for days and weeks on end, and daytime highs never recovered.

And while tender palms and winter vegetables never fell prey to a single night of subfreezing weather, they gradually deteriorated when they never had a chance to recover from the cold.

I’m telling you this in hopes of convincing you not only that the worst of the damage is yet to come, but also that there’s still an opportunity to prepare for it. If we hope to keep our tropical delusions alive, we may need to spend a little extra time in the garden this winter.

Tools to use for winter protection

Old sheets: Yes, theyre more effective than they look, and much safer and more effective than garbage bags and other improvised plastic coverings.

 Frost blankets: This specially designed horticultural cloth is a big advantage for serious winter vegetable gardeners, but it has many other uses around the yard. Its designed to let sunlight and air in, but keeps the temperatures inside several degrees warmer than the air temperature. That can make all the difference for growing plants like broccoli, mustard and turnips, which sometimes need just a few extra degrees of warmth to get them through our winters.

 Because it does breathe and doesnt easily overheat in sunlight, you can leave it on even during the day during the coldest spells. And when the coldest weather passes, you can simply lift it off, wad it up, and wait for the next cold one.

 Christmas trees: Sure. A thick branch of evergreen needles can hold heat well. I protected one of my young, half-hardy livistona palms with the remains of my neighbors Arizona cypress Christmas tree. I just cut off enough of the limbs to make a warm, evergreen tint to drape around the leaves and the bud.

 Leaf bags: Bags of moist leaves are among the most effective heaters in your garden. They not only hold heat in, they actually generate it as they decompose. In extreme cold, they release another burst of warmth as the water clinging to the leaves freezes.

 Water: Water does something you wouldnt expect: As it freezes, it actually releases heat, enough heat to warm the area around plants several degrees. Dont ask me why. It just does.

 Professional horticulturists use this trick all the time, but their techniques often require exceptional precision and painful timing. You have to keep a bare drizzle of water going during the entire freeze period  try that at home without specially calibrated sprinklers, and youre likely to do more damage than good.

 In the home garden, you can most effectively keep small plants warm with water by surrounding them with milk jugs, or with a specially designed commercially available Wall o Water, which can add up to 10 degrees of protection around small plants. My dad uses them to get an early start on tomatoes, and swears by them. If you use frost blankets, you can also experiment with sprinkling the blankets with water as the temperature drops, but of course, youll have to spend pretty much all night doing it.

 Insulation: The stuff you use in your attic, yes. Ive seen folks wrap their favorite palms with it. As with any wrap, it can add a few critical degrees of protection. But dont expect miracles. It doesnt (as leaf bags do) generate its own heat  it merely traps whatever heat the stem of the plant manages to give off. Because it comes in sheets, it can be difficult to wrap the most vulnerable parts of the plant, around the tips of limbs and (in palms) the growing bud. And you may run into problems if you leave it on all winter.

 Old-fashioned Christmas lights: Not the newfangled LEDs, but the big, luridly colored hot bulbs. String them along the boughs of a vulnerable citrus. Turn them on when temperatures drop below 25. Not the worlds most efficient heater, but it can add a few degrees of protection. Better yet, turn them on and cover the top of the tree with a sheet.

 A cardboard box: Amazingly good protection.

 A south- or east-facing porch: Its striking how much warmer my porch is than the garden a few feet away. Porches trap and store heat in many ways, particularly if theyre not exposed to prevailing northwest winds. Haul those potted plants up onto the porch and huddle them against the house.

What helps

1. Covering plants.

 It really is amazing how the simplest cover  a sheet, a layer of pine straw, old newspapers, a cardboard box  can make all the difference in the survival of many plants. Remember that covers work not so much because they keep cold out, but rather because they prevent heat from escaping so rapidly. The soil in your garden is a massive heat pump  if you can intercept even a fraction of that heat before it disappears into the night sky, you may well save your plant.

2. Protecting the BUD of tree ferns and tender palms.

 Its very difficult to protect the fronds of a tree fern or palm from cold. And if its cold enough to damage the trunk of your tree fern or palm, you can forget protecting it. But its not the leaves and trunk you should worry about  the secret to protecting these plants is to make sure you cover the single growing bud at the very top and center of the trunk. Protect that growing bud from cold, and youll likely save the plant.

 Sometimes, doing little more than wedging a good stuffing of leaves around and above the bud may be all thats needed to protect it. Wrapping the bud, turban-style, with cloth may also help.

 To prevent moisture problems, dont leave the bud covered more than a couple of weeks in a row, or allow an air pocket immediately around the bud.

3. Double bagging.

 Cloth loses conductive heat slowly, so its safe and effective even when placed directly on the tender parts of plants. Unfortunately, its porous, so it doesnt stop convective heat loss as well when the wind is blowing. A plastic bag or sheet does just the opposite. For the best protection, combine the best of both, placing first a cloth sheet, and then a plastic sheet loosely over it. Just be sure to remove the plastic sheet, at least, before the sun gets too high in the morning. 

4. Laying plants on the ground.

 You can learn this old trick by watching nursery operators. If youve got a big potted plant thats too big to move, gently lay the pot on its side, so that the trunk and branches of the tree are as close to the ground as possible. Then cover with a tarp. The heat generated by the ground and captured by the tarp may add 10 degrees of protection.


What makes things worse

1. Leaving plants covered with plastic sheets.

 Solid polytheylene or other plastic sheets, clear, black or colored, are dangerous when used by themselves. Clear plastic sheets are particularly damaging if left on the plants after the sun comes up. The greenhouse-like effect of the sun will burn leaves far more severely than the winter cold. But plastic sheets have another problem  they seem to drain heat from any object they touch. So if you do use plastic to cover plants, make sure you prop it up like a tent, with good airspace between the plant and the plastic. Or, as noted above, simply use two coverings  first put down a cloth sheet and then throw the plastic tarp over that for increased protection.

2. Tying sheets or tarps around the trunk of the plant.

 Much of the heat thats retained by sheets or tarps comes from the ground, not from the plant. So spread your sheets or tarps so that they can collect and trap ground heat  and weigh down or peg in the edges to keep it from blowing away.

3. Overprotecting plants the entire winter.

 While protection is good on the coldest nights  when temperatures drop below a plants ability to cope  you dont want to make them too comfortable for their own good. Exposing plants to typical winter temperatures is beneficial, because it reminds them that its too early to start growing. Keep them too warm for too long, and theyll start budding out like spring, and will actually become much more vulnerable to cold.

 So, for example, if you do decide to erect a tent-like greenhouse and warming lights around your new citrus or your hibiscus  which can raise temperatures dramatically  set it up so that you can easily remove the covering anytime temperatures rise above 28 or 30 degrees.

4. Cutting plants back.

 Unless the woody stems of your plants are black and turning to liquid, youre making a big mistake to cut into a plant this time of year.

 Burned leaves are NOT a sign that the plant is dead and needs trimming. All those brown banana leaves are helping to protect your banana trunks, which will very likely re-emerge green and fruitful next spring. Of course, if you cut the banana trunks down, youll never know.

 Ditto for burned hibiscus, tree ferns, palms, angels trumpets, citrus and other plants: Do NOT trim into the woody parts at all this time of year. Wait until at least April to start trimming, when it will be much clearer what wood was damaged and what wasnt.

 5. Covering hanging plants while theyre still hanging.

 It makes things worse because people delude themselves into thinking that theyre actually making things better. Remember: Coverings dont keep cold out  they keep heat in. If your potted plant is suspended in the air when you cover it, the only heat youre collecting is the insignificant thimbleful around the roots of the plant. If you want to protect potted plants, take them down, store them on the ground, against the house  and THEN cover with sheet. The sheet will hold in the abundant heat generated by the ground and your house.


Plants that will tough it out

These plants may look tropical, but they have a long history in Mobile, and will survive all but the very worst freezes of the century.

 Cabbage (sabal) palms  The most common palm on the Gulf Coast, and virtually a native.

 Jelly (pindo) palms  Another common palm that keeps on ticking. There are some that survived even the freeze of the century, back in the 80s.

 California fan palm (Washingtonia filifera)  Unlike its more slender Mexican cousin, mature specimens of the California fan seem to have survived Mobiles very worst winters.

 Chinese windmill palm (Trachycarpus fortunei)  This common and very hardy palm actually seems to grow better during cooler weather. Youll lose it to heat and rain before you lose it to cold.

 Camellias  If it gets much worse, you may lose some buds and flowers, but the plants should be just fine.

 Azaleas  If theyre not blooming, theres not much to worry about with the traditional azaleas (though this cold spell may answer some questions about how hardy the Encores will prove to be).

 Ornamental bananas  Dont worry, theyll be back from the roots to chase you around the yard next spring.

 Figs  In the event you lose a few branches to cold, the fig will simply be easier to pick next year.

 Mature satsumas  Oh, its gonna be close, but as long as it doesn't stay below 15 or 16 degrees too long, the trees should survive, though we may see some damage to leaves and smaller limbs. We can worry about that this spring. But see YOUNG satsumas below.

 Collards, kale, kohlrabi, garlic  Dont be too distressed by the sagging leaves. These plants should recover and produce tasty new greens or bulbs.

Plants on edge

These plants may survive, but they may need more attention than in winters past.

 Angels trumpets  Unless in a very protected place, your tops will be killed back every year, though they generally return in spring as long as the soil doesnt freeze. If this cold persists, however, we may have one of those unusual winters where the soil does freeze deep enough to wipe out your angels trumpets. Mulch around them deeply.

 Bananas, fruiting  Youre unlikely to lose your banana plant  it will almost certainly resprout from the roots  but if temperatures stay too low for too long, the above-ground trunks may melt and collapse, and youll lose any chance of producing banana fruit next year. This is a good year for banana fruit lovers to protect their 6-foot-high trunks  the ones large enough to fruit next year  with piles of leaf bags.

 Broccoli, mustards, turnips, beets, chard, lettuce  While these plants can withstand brief periods of freezing temperatures quite well, they dont do so well when the temperature drops below 25 degrees for long periods. Simply covering with a sheet or frost blanket may be all thats needed for most nights, though temperatures in the teens can be tough.

 Grapefruit  Most varieties are going to start having severe problems when temperatures around the trunk hit the lower 20s. The teens could be devastating. Fruits will be ruined by persistent temperatures in the mid-20s, so enjoy your fruit now, even if its not quite as ripe as youd like.

 Hibiscus, tropical  Were talking those big, multicolored Hawaiian hibiscus you buy at the Big Box stores, not the hardy Confederate rose hibiscus or our native hibiscus. The stems of the tropical hibiscus will be severely damaged, and the plant may be killed if the ground freezes. But mulch heavily around the roots, and dont cut the stems back until April. Theres a moderately good chance theyll return.

 Oleander  If the forecasts pan out, your big oleander bush is going to look pretty beat up, with lots of dead branches or trunks. But for better or for worse, it will probably survive. Dont cut it back until you see the new leaves developing next spring.

 Oranges  Some varieties, such as Hamlin, may survive temps in the teens with minor damage. But once the temperature drops below 22 degrees for very long, you can bet therell be leaf, limb and maybe trunk damage on most common commercial varieties. Young blood oranges seem particularly susceptible to bark splitting, so its a good idea to protect those trunks, as it will take the tree a very long time to recover.

 Queen palms  Hardy my foot. Queen palms really take it on the chin when temperatures drop into the low to mid-20s, particularly when it lingers, as this cold has. Ill be shocked if they make it through temperatures in the teens.

 Date palms  These are much hardier than queens, and have been known to survive brief drops in temperature down into the single digits. A few seem to have survived the better part of a century in Mobile. BUT the growing bud at the top of this desert plant seems to be very vulnerable to a combination of extended cold temperatures and moisture. If you have a lot invested in your date palms, it might be a good idea to find some way to use a protective fungicide around the growing bud as soon as the coldest temperatures pass.

 Potted plants  Even plants that are normally hardy will be more vulnerable to cold if they are in pots. The soil around their roots will freeze readily, as wind combines with cold to suck all the heat from the dirt.

 Young satsumas and palms  Older satsumas with big trunks may survive temperatures into the mid-teens, but young, thin-trunked palms and citrus need extra protection. Even if temperatures drop only into the mid-20s, Id snuggle leaf bags around young palms or the vulnerable graft of citrus, a few inches above the ground. And to limit leaf and limb damage, it would be a good idea to throw a big sheet or frost blanket over the entire plant.

 Tree ferns  Thanks to a protected growing area and several warm winters, I have a big one, with an 8-foot-tall trunk and leaves that spread 15 feet high. But I know its living on borrowed time  and I doubt it will long survive temperatures in the lower 20s. I always protect the growing bud as carefully as possible, so that even if the leaves are burned off completely, it may return next year. But I wouldnt be surprised if this year were its last. 

Fun while it lasted

Limes  If your Mexican (or Key) lime is planted in the ground outdoors, and it survives this winter without protection, you drop me a note and brag about it. Limes cant long tolerate temperatures below 30 degrees. Grow em in pots that can be moved.

 Lemons  True lemons (not the Meyer lemon hybrids most often grown here) wont tolerate temperatures much below 26 to 28 degrees for extended periods. They belong in pots.