Posts Tagged ‘cold frame’

Homegrown Vegetables Hall of Fame II: Leaf Lettuce

June 1, 2009

Sometime between when I was a child and the present, the world at large made a leap from iceberg lettuce to romaine.  Back then, every family had a volleyball-like, pale green head of iceberg lettuce in the refrigerator crisper.  Nowadays, the only times I see iceberg lettuce is at the Taco Bell or in a wedge salad.
This shift is understandable–iceberg lettuce is devoid of nutrition and flavor.  Romaine is able to hold up to heavy dressings and gets great ratings as  “leafy green”, one of the foods most people don’t eat enough of.  However, this shift in lettuce preference skipped over my personal favorite–leaf lettuce.  It’s easier to grow than either iceburg lettuce and romaine, and offers a far greater variety in form than either.  I can see why it doesn’t work as well on a commercial level–each head is a lot smaller than either iceburg or romaine lettuce, and it probably doesn’t transport as well, but for the home gardener, it’s ideal.

Growing Lettuce

Lettuce is a cool-weather crop, and will flower and set seed when it gets too warm.  In Michigan, I can usually get lettuce from my full-sun garden until the end of June.  If I start it in a cold frame, I can put it in in March, and start getting some thinnings in April.  A 4 x 4 area provides a few salads every few days through May and June, depending on weather.   This year, I’ve got some transplants and some grown from seed in the same bed, and they’re pretty indistinguishable at this point–next year, I’ll probably direct-seed them all.

Mulching is beneficial on two fronts–it keeps the soil moist and keeps the soil from splashing on the plant.  Lettuce likes a damp soil, and will wilt in hot, dry weather.  A good coating of mulch keeps the water in the soil from evaporating.  Mulch also keeps the soil in place through sprinkling or rain, as the leaves can get sandy otherwise.  Mulch with caution, however:  slugs love to eat lettuce, and too much mulch will give them the cover they need to destroy your crop.

Lettuce works well when planted in combination with other plants.   I’ve interplanted it with carrots, as the long and narrow carrot roots do not interfere with lettuce’s more shallow roots.  I’ve planted it between rows of corn, with the corn protecting the lettuce from the summer sun and extending its season.  I’ve also planted lettuce in a spot where I intend to plant a hot-weather vegetable–tomatoes or peppers, for example–as the lettuce will get pulled out when the hot-weather plants need the space.  There is some overlap in growing seasons, but the peppers/tomatoes don’t really get growing until the lettuce is past its prime.

I’ve had mixed results growing a fall crop of lettuce.  Timing is crucial–if you get it in too soon, the hot weather causes it to “bolt”, get bitter, and go to seed.  Plant too late, and the seedlings never develop.  I haven’t got a foolproof technique yet–I try it every year, and some years I have better luck than others.

Eating Lettuce

The first time I have to buy lettuce from the store (usually around November) is the most disappointing trip of the year.  After several months of right-out-of-the-ground lettuce, even the freshest grocery store offerings look tough, wilted, and bruised.  Fresh, home-grown lettuce is truly a luxury.  There are recipes for lettuce slaw and lettuce soup, but I’ve never needed them–a frilly leaf or two on a sandwich and a big salad are the only ways I’ve used lettuce.  We always offer to bring a green salad to the early-summer, bring-a-dish-to-pass events, too.  A few green onions, a shredded carrot, and a hardboiled egg, all topped with chive blossoms or pansy flowers, make for a very impressive, I-grew-it-myself salad and seems to go over well with most audiences.

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Winter Greens, Part II: The Cold Frame

March 22, 2009

This entry is a follow-up to my article on sprouts several weeks ago.

I planned on being able to post digital pictures before I wrote this, but that’s not happening.  In addition to sprouting various seeds, some home-grown and others from the store, I add fresh local vegetables to my winter diet through the use of a cold-frame.  I have had less than spectacular results, and a few meteorological mishaps, but the idea is worth sharing.

In my last entry, I gave a plan for an insulated straw-bale cold frame.  This year, I didn’t get enough bales before winter, so I used an alternate design–a variation on a hoop house.  I picked up about 75 ‘ of concrete reinforcing mesh–sort of an industrial-strength chicken wire with 6″ holes–to make tomato cages and a compost bin.  With the 15 or so feet I had left over, I made two sections that arced into a half-circle shape, about as wide as one of the beds in my garden.  Each section was cut to leave 6″ lengths of wire sticking out on the ends, which I stuck into the ground to secure the frame.  This left me with a wire tunnel, about 5 feet long, 4 feet wide, and 3 feet tall.  I was able to get some greenhouse-grade plastic (leftovers from a local greenhouse) to cover my frame, and weighed down the edges with some fist-sized rocks.  This left me with a miniature version of the full-sized greenhouses you’d see at a commercial-scale nursery.

The cold frame collects and retains solar energy, resulting in, well, a “greenhouse effect” that keeps the plants within at a much warmer temperature than the outside air.  Though this would only add a week or two to the life of warm weather plants, like peppers or tomatoes, it can keep cool-weather plants alive through all but the coldest Michigan winters.

Fall and Spring Planting in a Cold Frame

I stuck with cool-season greens in the fall, such as leaf lettuce, bok choy, and spinach, planted in the early fall or transplanted a little later.  These go more or less dormant when the weather gets cold, but the cold frame keeps them in a harvestable state through most of winter.  There isn’t a lot of growth, so your stock dwindles as spring approaches, but it’s a great way to keep some fresh and local food on the table all winter.  With no disrespect to the other two winter-long green vegetables, it’s way more interesting than kale, and far more versatile than brussel sprouts.

In spring, the cold frame is more of a head-start than a long-term plan.  Around the time I’m planting pea seeds, I pull out the rest of the winter greens from the cold frame (there’s usually not much left, and what’s left is starting to toughen up and flower), and plant a new crop.  This year, it was spinach, bok choy, leaf lettuce, and very early carrots.  The additional heat and humidity from the enclosed cold frame will give them several weeks of extra growing time before the open-air garden is ready to be planted.  I’ve sited the cold frame in the place I’m putting this year’s peppers, which won’t be planted until early summer, so most of these plants will have a chance to mature before the peppers go in.  I’ve considered putting the peppers in a few weeks before the last frost, hoping that the cold frame would give them the shelter and warmth they would need, but I don’t think it’s worth the risk.  I’m not sure how cold it can get in a cold frame, particularly at night.

Cold Frame Problems

Weather rarely cooperates with cold frame construction.  I’ve had my plastic sheeting blown off completely, despite weighing down the edges and clipping the plastic to the frame.  I’ve also had the entire thing collapse under the weight of snow and ice, crushing the leafy plants underneath.  Also, since the plastic sheeting is impermeable to rain, it can get desert-dry inside of a cold frame when all the ground moisture is frozen.

Access to vegetables is another problem.  With rocks weighing down the edges, water sometimes pools and freezes, making it hard to lift the plastic sheeting and reach in to harvest.  The 6″ access holes are also an obstacle.  I’ve adopted a “mass harvest” mentality, getting a week’s worth of greens in one go, just to simplify things.

Once spring starts to warm up, it can get very hot inside a greenhouse.  Think of a car parked in the sun with the windows up–opening up the cold frame on those warm, sunny days is a necessary inconvenience.

Weeds that are growing in the space where you’ve set up your cold frame are also able to take advantage of the microclimate, so they often spread throughout the winter.  Finally, keeping a bed in production all year takes a lot out of the soil, so your cold-frame bed should be refreshed with compost or fertilizer more often than others.

Possible Improvements

I’ve considered a number of options that I haven’t followed through on yet.  The first–instead of using weights to hold down the plastic, I’ve seen cold frames with trenches dug along their edges, with the edge of the plastic sheet buried under a few inches of soil.  This would hold it down a lot better, but would make it much harder to get into the cold frame.

Another modification would be to put it in so that it straddled two beds, with a path down the center.  I’d have to crawl in from the end (the taller a cold frame is, the less efficient it is, as heat rises away from the plants), but I wouldn’t have to reach, and I’d be able to bury the edges as mentioned above.

I’ve saved up a bunch of dark-colored laundry soap jugs, which I intend to fill with water and use as heat collectors.  The dark colors will absorb solar heat through the day, then release it at night.  Each jug takes up valuable square footage in the cold frame, though.

I may use a few stakes next year to reinforce the wire framework–I’ve never had a collapse before, but this year’s heavy snowfall brought the whole cold frame down.  It’s an easy enough fix, and I could have saved a few plants.

So far, using a cold frame has been more art than science, but it has kept in in the garden throughout the winter, and kept me out of the produce section of the grocery store for several weeks beyond the end of my garden’s regular season.  I’ll be building another straw-bale frame next year, provided I can round up enough free straw bales, but I’ll build another wire-frame hoop house as well, just to see if I can do any better.

First Signs of Spring

March 6, 2008

We’ve melted off a huge amount of the nearly two feet of snow that has accumulated since our mid-70s days in January, and I’m seeing traces of edibles coming up in the yard. Normally, around this time, I would be putting lettuce, spinach, and bok choy into a cold-frame greenhouse, but a terrifically windy storm has sidelined that structure. I’ll need a good, long weekend to reassemble it, and it may be warm enough to open-seed by the time one of those come along.

Last fall, I put in three patches of rhubarb around the house. I found a woman online who was thinning her patch, and I picked up a few plastic shopping bags full of trimmed roots off her porch. One of my three spots is still covered in snow, but the other two have apparently survived both a very wild winter and my incompetent transplanting technique. This is the first time I’ve seen rhubarb sprouting, and it looks weird–like bright red button mushrooms. I’m not sure how long I’m going to have to wait to eat some, but I’m eagerly anticipating some rhubarb cobbler.

Also last year, I found some artichoke seeds at a farm supply store. Of the four seeds in the packet, one sprouted. Artichoke is not winter hardy in my area, so I planted it up against the house’s foundation in the hope that that would be warm enough to keep it alive through the winter. I upended a bucket filled with dry leaves over it as further insulation, and piled snow on top of it through the winter. I peeked during a warm day, and there doesn’t appear to be any growth yet. Time will tell if it returns or not. An eternal optimist, I’ve already purchased another packet of artichoke seeds this year. Fresh, homegrown artichokes are an enticing enough return to justify significant risk.

Asparagus is entering it’s second year, at which point the very impatient are allowed to do some very light harvesting. However, there is no sign of asapargus in the garden, yet.

Garlic, on the other hand, is looking beautiful. Last october, about the time I was putting in tulips and daffodils, I broke up some of last year’s garlic, harvested that July. I put the biggest cloves a few inches into the ground about 6 inches apart. They put up a little growth last year, and are back at it this spring. Planting them early gives them a month or two to build a root structure before winter’s freeze, at which point they go dormant. As spring arrives, the garlic is well established and ready to begin the growing season. It’s hard to do garlic wrong.

I can finally find last fall’s kale, which I’ll need to use before it starts growing again. The same goes for parsley. It won’t be long before the first of the wild greens start growing. I’m making a point this year of trying a few of them, which is slightly terrifying–most of them become unfit for human consuption at some point in their growing season, some to the point of being lethally poisonous. Should this weblog suddenly go dark, blame pokeweed.

Worm Update

Seeing as my worm post was far and away my most visited, I’ll give a brief update on my livestock. I continued to have problems with the worms congregating along the rim of the containter, although it was never as bad as the first day. I tried a number of solutions–adding water to increase moisture, adding dry bedding to decrease moisture, “fluffing” the bedding to add oxygen, and relocating the bin to adjust the temperature. I’ve settled on removing the lid and covering the bedding with a black plastic garbage bag, and it seems to be working. The lid, apparently, was a bit too airtight for the worms’ comfort, and the plastic bag fixes that without letting moisture out or light in.