By Sommer Cartier.
Just when temperatures are heating up, a cool, fresh, crisp salad sounds like bliss. It can be incredibly disappointing when you go to the garden and find tough, bitter lettuce with sun-scorched edges. Luckily, for those of us who love our tender greens during those hot summer months, there are three strategies we can employ to keep lettuce sweet, crisp, and fresh!
Alter Your Lettuce Growing Climate
There are a few techniques that can be implemented to provide a cooler growing climate for your lettuce. First, look for garden space that provides morning sun and afternoon shade. Lettuce prefers direct sun when the rays are more moderate. If these conditions don’t exist, create shade for your prized lettuce. Underplant lettuce among taller, fuller plants such as tomatoes and eggplants. A favorite combination is lettuce and beans—these plants are natural companions. Lettuce demands more nitrogen while beans work with the atmosphere and soil bacteria to deposit nitrogen in the soil, feeding neighboring plants. You can provide support for beans in a number ways. A set of stakes in the form of a circle and tied above is called a bean teepee. When lettuce is planted within the circle, or along the north-facing outer rim, the beans provides shelter and relief from the sun’s summer rays.
Shade cloth can also provide a cooler climate for growing lettuce. This fabric provides between thirty and forty percent shade and can be purchased at most garden centers. Drape the shade cloth over a wooden frame above the lettuce or, using clothes pins, secure it to ¾-inch PVC pipe or metal hoops arched over the lettuce.
Plant Heat Resistant Varieties
The lettuce family consists of four basic types: Butterhead, Leaf/Oakleaf, Crisphead, and Romaine. Within these families are varieties that tolerate heat and are slow to bolt. (Bolting is a term used to describe edibles and ornamentals that produce flowering stems and go to seed before they've been harvested.) In warmer temperatures, lettuce tends to shift its energy towards producing seed and the plant begins to grow upwards, becoming tough and bitter. By cultivating lettuce varieties that tolerate heat, you can extend your lettuce growing season and perhaps grow year-round. Below are popular heat tolerant lettuce varieties. Look for the words 'Heat Resistant' or 'Slow Bolting' on your seed packets.
1. Butterhead: in general, butterheads are moderately heat tolerant.
Buttercrunch Bibb
Captain Bibb
2. Leaf/Oakleaf: generally heat tolerant.
Deer Tongue
Oakleaf
Lolla Rosa
3. Crisphead: tend to be more difficult to grow and do not agree with warm temperatures; some fare better than others.
• Nevada
• Sierra
• Anuenue Batavian
4. Romaine: can be tough to grow in heat, though there are more heat tolerant varieties.
Jericho
Coastal Star
Little Gem
Create Soil Conditions That Lock in Moisture
To help prevent soil from drying out, add lots of organic matter in the form of compost. Organic matter acts like a sponge by retaining moisture for longer periods of time. Mulching can also help lock in moisture. And finally, make sure you water your lettuce in the morning or late afternoon and before the soil becomes dry. Provide deep, thorough waterings. Lettuce grows best when its roots are encouraged to stretch outwards towards water.
Now that you have the necessary tools for growing summer greens, 'lettuce' turn up the heat and start planting! Enjoy those crisp, refreshing home-grown salads this summer.