Stretching my salad days

The Eastern prickly pear or Indian fig (Opuntia humifusa) actually grows wild throughout the eastern parts of North America.

Brrrr! The mercury plummeted to nine degrees Fahrenheit in my garden last week – which is why I am amazed to be still harvesting fresh salad greens. And I don’t mean kale and Brussels sprouts; they’re tasty and still available in my “back 40,” but tender and succulent they are not. Likewise, I don’t mean turnips, carrots or other root crops that can nestle in the relative warmth of the earth. (My root crops have been pulled and packed away into a box for winter storage.)

What I am talking about are lettuce, endive and Chinese cabbage. These vegetables, which are tender and succulent, must have antifreeze in their cells to be able to remain so in the face of such cold temperatures. Actually, that’s not far off: With gradual exposure to increasingly colder temperatures, cold-hardy plants are able to move water out of their cells into the spaces between the cells, where freezing would cause less damage. Moving water out of the cells also concentrates the solution within the cells and – if you remember from your high school Chemistry – concentrating a solution lowers the temperature at which it freezes. Warming weather reverses the process.

Mother Nature got a little hand from me in the form of row covers, which are diaphanous blankets thrown over plants to offer them additional frost protection. Spun-bonded row covers let light and water pass through. I’ve used these materials in spring and autumn for many years; but looking through the Harris Seeds catalogue (www.harrisseeds.com), I came across a “point-bonded row cover,” which was said to give plants an additional eight degrees or more of cold protection. That’s a lot.

A few weeks ago, I set metal arches (made from five-foot lengths of concrete block truss reinforcement) over the rows, cut the row cover to six-foot widths and laid it over the hoops, secured by additional metal hoops over the row cover. The material evidently is very effective; my guess is that endive and lettuce are cold-hardy to the low 20s and the row cover would bring protection down to the low-to-mid-teens. But this was nine degrees!

Row covers represent a tradeoff between cold protection and light transmittance. Generally, the heavier the row cover material, the warmer the temperature under the cover and the less light that reaches the plants.

So in early spring, I’ve used a 1.25-ounce cover to speed along growth of new plants. This cover lets about 70 percent of the sunlight penetrate and keeps plants about three degrees warmer than outside the cover. In early summer, I use an even lighter-weight material, 0.55 ounce, to cover my eggplants so that flea beetles don’t ravage them. Eighty-five percent of sunlight makes it through this lightweight material.

The point-bonded row cover is a heavier material than row covers that I’ve used in the past. Endive, lettuce and Chinese cabbages are now snuggled under two-ounce fabric. Only about 30 percent of the sunlight – which is sparse anyway this time of year – makes it through this material. But the plants are fully grown, so don’t need to grow. To just stay alive, now, they need cold protection more than light.

So I’m driving along here in Ulster County, New York, and what do I see growing wild along the roadside? A cactus. A cactus growing wild outdoors wouldn’t be an oddity in Arizona, but New York doesn’t have the climate and soils usually associated with cacti.

The Eastern prickly pear or Indian fig (Opuntia humifusa) actually grows wild throughout the eastern parts of North America. You’re most likely to come upon the plant growing in a sunny spot in well-drained soil. Not the one I found, though: This plant was growing on a rock face, which is well-drained, on an east-facing slope right at the edge of woods – not particularly sunny.

Prickly pear cactus can be oddly attractive, even edible. The pads, once the spines have been rubbed off (not with bare hands), can eaten be raw or cooked. The red fruits are also edible. The Opuntia species usually eaten is O. ficus-indica, which is not hardy in cold climates. Even that species never tasted that good to me, so I wasn’t eager to try eating any of the roadside plant. Also, in New York, Eastern prickly pear is classified as an “‘exploitably vulnerable species,’” which means plants “likely to become threatened in the near future throughout all or a significant portion of their ranges within the state if causal factors continue unchecked.”

I lied; I did pick off one fruit for tasting. It was seedy and flavorless. All was not exploitive, though, because I am planting the seeds.

Any gardening questions? E-mail them to me at garden@leereich.com and I’ll try answering them directly or in this column. Come visit my garden at www.leereich.blogspot.com and check out my new, instructional videos at www.youtube.com/leereichfarmden. For more on local homes and gardens, go to Ulster Publishing’s www.homehudsonvalley.com.

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