Is a building or a tree shading your garden or backyard? Do you want to start growing some simple vegetables, like lettuce, but worry they won’t get enough sunlight to grow and mature? Well, you’re in luck. Lettuce is one of the easiest vegetables to grow, and it does well in the shade.
When growing vegetables, you can follow this good rule of thumb: crops that produce fruits and roots grow best in full sun, while crops that are leafy can tolerate, and sometimes even thrive in the shade. This is true not only for lettuce but also for most leafy greens like cabbage, mustards, mizunas, arugula, spinach, sorrel, etc.
Lettuce is a cold-hardy crop that loves temperatures on the cooler side and can tolerate shade. In early spring, lettuce grows faster if planted in full sun, but if the weather gets too hot, it will go to seed. Partial shade will keep lettuce from bolting too soon during the summer months.
How much sun does lettuce need?
Lettuce is forgiving in terms of sunlight, but if you’re planning to grow it in a shaded space, you need to determine if that spot is fully shaded or only partially shaded. So what’s the difference between full shade and part shade in gardening terms?
- Full shade – gets between 2 to 4 hours of direct sunlight per day;
- Part shade – gets between 4 to 6 hours of direct sunlight, preferably mild morning sun.
Lettuce typically needs a minimum of 6 hours of direct sunlight per day, although it will do well on less than that. A partially shaded environment will work best. Keep in mind that lettuce seeds need some light to germinate, so perhaps transplant them instead of sowing them directly in the shade.
So what happens if you give lettuce full sun? In the early spring months, the sun’s heat is nothing but beneficial to most plants, lettuce included. Everything tends to grow faster and more vigorous. But as the days get longer, lettuce will concentrate its energy into growing its stalk and producing flowers, which will lead to bitter, inedible leaves. This is a process known as bolting.
Can you stop lettuce from bolting?
Lettuce will grow in most conditions, and we can often use shade to our advantage. In fact, most gardeners use the sunniest spots of their garden for heat-loving plants and reserve the shady areas for quick maturing leafy greens that are quick to bolt in the heat of summer.
Bolting in lettuce has a lot to do with high temperatures. Lettuce is a cold-hardy crop and grows best when temperatures reach 55 to 65°F (13 to 18°C). But anything higher than 70°F (21°C) will trigger some cultivars to go to seed. This process is inevitable, but we can find ways to prolong cropping by using mulch, shade, and selecting bolt-resistant varieties.
Day length is another factor that will lead to bolting. Lettuce is a long-day plant, which means that it will set flowers as the days get longer and the plant gets more hours of sunlight.
Planting lettuce in the shade during hot months will stunt its growth and won’t allow it to go to seed. The downside to this is that most plants will develop slower when planted in full shade. But during those torrid months, I’d say baby lettuce is better than no lettuce at all.
How to shade lettuce in summertime?
So now that we’ve determined that shade – particularly partial shade – is a good thing in our gardens, how do we use it to grow lettuce in the summertime when those tender leaves need protection?
Here are 5 ways to use any patch of shade you can find in your garden to your advantage:
1. Interplant lettuce in between taller plants.
Whether you’re growing lettuce for heads or leaves, it’s a quick maturing crop. Most lettuce varieties will be ready for picking in 45 to 55 days. Sow them in between tall, stalky plants, like peppers, tomatoes, kale, broccoli, etc. The lettuce seedlings will get enough sun during the early summer months, but soon enough, the neighboring plants will grow a dense canopy of leaves. This will protect them from the heat and slow down the bolting process.
2. Leverage the shade from trellises.
Vertical gardening is great for increasing productivity in small spaces. Climbing plants like cucumber, squash, or beans get better airflow when grown on trellises, and the added advantage is that they cast shade when it matters the most – anywhere from June to September.
Plan for the shade cast by these structures and sow or transplant your lettuce in sheltered areas: you can place them at the base of a bamboo teepee, underneath a cattle panel arch trellis, or under the heavy shade of a pallet trellis. Lettuce will make a great ground cover, keeping humidity levels in check.
3. Follow the shade cast by your structures.
Judging by the amount of shade we see in the spring or winter months, we falsely assume that some corners of our garden are completely shaded at all times. But as the seasons progress, the sun’s angle changes by 50%, and many shaded areas start receiving full sun in the summer months.
If you have permanent structures in your garden – like a fence, a shed, a tall tree, or a neighboring wall – observe the amount of shade they cast in the summertime and even keep a log of how many hours of direct sunlight they get. This way, you may avoid sowing lettuce in an area that’s shaded in spring but completely scorched in summer.
4. Use shade cloth to protect your lettuce plants.
You can protect your lettuce from too much heat by creating a supporting structure and covering it with shade cloth. You can build your own DIY frame using PVC pipes or buy tall hoops for adequate support.
Shade cloth cuts down on UV penetration while at the same time allowing rainfall to pass through. It keeps the shaded area significantly cooler while also keeping birds away. Professional shade cloths are lightweight and dark in color. Choose a 60% density shade cloth for protecting lettuce.
A cheaper alternative for shade cloth is burlap or a dark sheet of cotton. They offer less UV filtering but make good options if you have them around the house.
5. Grow lettuce inside containers that you can easily move.
Lettuce is a shallow-rooted plant, and it can be grown easily grown in containers. This way, you get the best of both worlds – you can move those containers around to follow the sun when the seedlings are growing and set them in the shade to prevent them from going bitter when it’s time for harvest.
Grow lettuce plants on your patio, terrace, or balcony. If you have some potting mix, water, and a few hours of sunlight, then you can grow lettuce – and so much more. If you’re short on space, you can grow your own lettuce tower – check out these amazing vertical structures that are perfect for growing greens, strawberries, herbs, and other shallow-rooted plants.
Lettuce cultivars that are bolt-resistant
Lettuce is such a staple in our diets that we just had to find a way to make it last all summer. Enter: the bolt-resistant lettuce varieties. Whether it’s looseleaf, butterhead, crisphead, or romaine, you can test these seeds and enjoy fresh lettuce leaves or heads all summer long:
- Looseleaf: Red Salad Bowl, Green Salad Bowl, Lollo Rossa, Lollo Bionda, Oakleaf Looseleaf, Bronze Arrow Looseleaf;
- Crisphead: Sierra Batavian, French Batavian;
- Butterhead: All Year Round Lettuce, Merveille De Quatre Saisons, Adriana, Capitan Bibb;
- Romaine: Jericho, Coastal Star, Salvius.
Despite being bolt resistant, many of these seeds won’t germinate in the heat of summer, so find other ways to get them to sprout. I start them indoors under grow lights where I can control temperature and humidity levels even in warmer months.
Don’t be afraid to use shade to your advantage when growing lettuce. It keeps your lettuce plants fresh and tender for longer. Learn to maximize any shade you get in your garden during the summer months for growing all kinds of leafy greens.
The shade will also make your lettuce plants crisper when it’s time for harvest. Never pick lettuce at noon, when the plants are wilted and dehydrated. Instead, harvest lettuce leaves or heads in the morning or on an overcast, rainy day.