Monday, January 10, 2011

Baby, it's cold outside!

The Arctic blast has reached Central Texas, with temperatures in the 30's all day. It's currently 36°F outside and misting: four more degrees, and we'll have flurries. Brrrr!

Luckily, last Saturday was gorgeously warm and sunny: a perfect day to get ready for the freeze with a boatload of floating row cover. We covered the hoop houses over the veggie beds, and tweaked the makeshift greenhouses around our baby lime trees.
Putting up makeshift greenhouses

Lime trees hate freezing temperatures; they start sulking at 32°F. And by sulking, I mean the tips of their branches freeze off, they drop all their leaves, and they produce no fruit the following year. So last year, we used tomato cages, rope lights and floating row cover to keep the ambient temperatures around the trees above freezing.
Key lime tree

Every time the weatherman threatened a freeze, we'd run out and throw floating row cover over the cages, and turn on the rope lights. In the morning, when things warmed up, we'd take off the row cover and turn off the lights. All winter long, those lime trees kept us running; throwing the row cover on, taking the row cover off -- on, off, on, off -- hey, it sure beats lugging two huge potted lime trees in and out of the garage. Moreover, it worked. Our Bearss lime rewarded us handsomely for our efforts with two dozen fresh limes, and believe you me, there are few things better than a Margarita made with fresh, homegrown limes. Although the key lime produced only a couple of limes, it did put on tons of new growth.

This winter, the tomato cages were much too small for our growing trees, so Jack came up with a bigger, better idea. Instead of tomato cages, he purchased eight superlong pieces of 3/8" rebar, and drove them into the ground around the periphery of each tree, foursquare or thereabouts, roughly 6 feet apart.

We then took a 25 foot long length of 12' floating row cover from the Natural Gardener, and anchored it at the 6' point to the rebar with cheap binder clips from the office supply store, allowing about a foot to puddle on the ground and the remaining 4-5' to overlap on top of the tree.
Binder clip

Floating row cover provides about four to six degrees of frost protection, so on nights when temperatures below 28°F are expected, an additional heat source is helpful. We use inexpensive clip lights with 60W incandescent bulbs underneath the row cover. I'm not sure what we'll use when these bulbs go the way of the Walkman, as compact fluorescent lights give off no heat.
Clip light as heat source

One big difference this year: no more on-off-on-off with the row cover. This year, we've decided to keep the lime trees ensconced in their snug little rugs all winter until the risk of frost has passed; typically, that's around March 15 in these parts. Unlike other coverings like bedsheets and plastic, floating row cover is penetrable by water and light, and won't suffocate the plant when temperatures rise.
Makeshift greenhouse

These contraptions have been up since the first frost in November, so this past Saturday, we took down the row cover around the Bearss lime to check how things were going inside. Happily, most of the tree looked nice and green.
Bearss lime

Unfortunately, there was a bit of freeze damage on the branches that were touching the row cover; nothing major, but definitely a sign we needed to move the rebar further out away from the tree before re-wrapping it in row cover.
Slight frost damage on Bearss lime

We didn't take down the makeshift greenhouse around the key lime; we didn't have to. I peeked inside, and even the branches touching the row cover looked great. The tree was so happy, it was blossoming.
Key lime blossoms

I even spied a few baby limes. They'll likely fall off before spring, but it's an encouraging sign of bountiful harvests to come this year. I'm already dreaming of Key Lime Pie.
Baby key limes

At night, with the lights on, the makeshift greenhouses look like some sort of funky light sculptures.
Makeshift greenhouse with clip light

Which plants in your garden get extry-special treatment in winter?

Words and photos © 2009-2011 Caroline Homer for "The Shovel-Ready Garden". Unauthorized reproduction is prohibited.


  1. It is chilly outside! I cover up my containers. We don't have much room in the garage or I would put them in there. Looks like you have it down to a science. Your lime trees look healthy.

  2. Not too much. Just the tender succulents in pots, which I either bring inside or throw a sheet over. Anything wimpier has to suck it up or die. :-)

  3. You guys are serious about margaritas! In winters of 2008-9 and 2009-10 we made our in-ground lemon and lime into Citrus Ghosts, too, but even with lights & tents the 13°F of Jan 2010 meant no fruit. I didn't even try to save them this year - even recycled the fabric for other plants! I guess you're a better plant-mom, Caroline ;-]

    Annie at the Transplantable Rose