By Barbara Damrosch
Special to The Washington Post
Thursday, May 14, 2009
There are summer days when all you want to do is sit under a big, leafy tree -- and bring your plants with you. The lettuce is wilting in the glare, and you can just hear it say, "I'm out of here. I'm bolting."
One solution is to focus on heat-loving crops such as melons and save the greens for cooler days. But summer is long, and there are ways to shade plants to the point where Batavian lettuces or crispheads might muddle through to yield a more varied diet.
Sowing part of the garden under the fringes of a tree is one solution. You wouldn't choose a maple, with its dense canopy and shallow root system. Trees that have a more open leaf pattern, such as honeylocust, dogwood and birch, offer dappled shade, letting in enough light for the plants to thrive.
You can also achieve a dappled pattern with man-made devices. In commercial agriculture, the common solution is shade cloth, a plastic fabric that lets in a given percentage of light, with 50 percent being the ideal for sun-sensitive food crops. The trouble is, most shade cloth available to home customers is designed for shading people and lets in too little sun. It is often dark in color, which, by absorbing heat, can make the air under it even hotter. Greenhouse supply companies offer more options, including aluminized mesh that reflects heat instead. Growers Supply (http://www.growerssupply.com) is one source.
Here's an even better solution: an old-fashioned lath house. Lath is simply narrow strips of wood, often used in trellises, and a lath house is a frame structure with a lattice roof supported by posts. Some lath houses have lattice on all sides. With the spaces between the strips equal to their width, they do the perfect job. You may have seen similar devices in garden centers, with hanging baskets suspended within.
Building a lath house is not difficult. One shortcut is to use snow fencing, which is rolls of lath strips wired together, but if you do, try to find a type in natural wood, not the kind that is a bright, screaming orange.
It's best to use a rot-resistant (not pressure-treated) wood, such as cedar. Sometimes you can find pre-fabricated lattice panels for sale. These can also be placed on top of a cold frame for lettuce and other low-to-the-ground crops, an excellent way to put your cold frame to summer use.
Even if your lettuce gave up on you last week, it's not too late to put up a lath structure. You'll find it an attractive addition to the yard, with many uses. It's a perfect place to harden off seedlings in spring, by easing the transition from indoor to outdoor light, or for bringing fall crops along in pots or flats before setting them out in the garden in cooler weather.
He who laths last is still way ahead of the game.