Growing Lettuce

Growing lettuce is relatively easy. Well, as long as it is cool enough. Unfortunately, lettuce is NOT a tropical plant. In the tropics you can only grow lettuce during the cooler months. Lettuce does NOT like hot weather. In warmer areas, such as Northern Australia, lettuce can also be grown outdoors throughout the winter. Increasing daylight hours and hot temperatures stimulates lettuce to bolt, which makes growing lettuce more challenging during the summer months.

Growing lettuce is an easy and inexpensive way to put fresh gourmet salad greens on the table. As a cool-season crop, lettuce grows well with the cool, moist weather available in spring autumn. In cooler climates, the lettuce growing season can also be extended year-round using an indoor hydroponic system.

Why You Should Grow Lettuce

Have you ever tasted a lettuce fresh from the garden? I mean, FRESH? Picked less than 30 minutes ago? It's amazingly delicious! You will never settle for shop lettuce again after you tasted a truly fresh garden lettuce. The flavour still beats the shop lettuces any day, but it's definitely not the same as a garden-fresh lettuce. That's one reason to grow lettuce.

The other reason to grow lettuce is that lettuces are so incredibly ornamental. You know I don't believe in the separation of a strictly defined "veggie patch", kept separate from the ornamental part of the garden.

Do you know how many colourful varieties with different kinds of leaves there are. You can plant the most beautiful swirls and patterns just out of lettuce. But even individual plants or clumps of a few, strategically placed, can look as gorgeous as any typical bedding flower.

 When to Plant Lettuce.

The lettuce growing season begins in early spring and extends through autumn for colder climates. In warmer areas, such as Northern Australia, lettuce can also be grown outdoors throughout the winter. Increasing daylight hours and hot temperatures stimulates lettuce to bolt, which makes growing lettuce more challenging during the summer months. As a cool-season crop, lettuce can be direct-seeded into the garden as soon as the soil can be worked in the spring. Lettuce can also be started or grown indoors. Try succession planting and growing varieties of lettuce with differing maturity times to harvest lettuce plants throughout the growing season.

What Lettuces love and hate.

Lettuces need good soil. It should be light, free draining and rich in organic matter. It needs to hold lots of water and lots of nitrogen and other nutrients.

Lettuces taste best when they are grown as fast as possible and for that they need water and food.

Lettuces need lots of everything, and they want a steady supply of it. Any set back they suffer will at least make them tough and bitter, at worst it will cause them to bolt to seed straight away without making any leaves for you. So, make sure they never get stressed (e.g., by forgetting to water them).

Lettuce has shallow roots, so it dries out easily!

Any gardening book (all written for cooler climates) will tell you that full sun is essential. Full sun is best ONLY when it isn't too hot. Once the temperatures approach the thirties, your lettuce will definitely appreciate some shade!

Growing Lettuce from Seed

 Direct seeding is the easiest way to grow lettuce. Either spread the seed very thinly along a row and cover lightly with soil, or sprinkle it over a bed and rake it in. Lettuce seed is very fine and not easy to spread evenly, therefore both methods will likely require you to thin your seedlings later.

Lettuce seeds usually germinate within seven to ten days but can take as little as two or as long as twelve days. It depends on the variety, the temperature, the moisture and other factors.

To thin your seedlings if they are too dense, cut the surplus lettuce plants rather than pulling them out, so you don't damage the roots of the neighbouring plants.

Direct seeding will likely cause some losses. Emerging lettuce seedlings are very vulnerable to all sorts of bugs. Slugs love them, so do grass and leaf hoppers, and earwigs and other soil insects can get them before they even break the surface. Also, lettuces grow very slowly in the beginning and are easily overgrown by weeds.

You can also grow your lettuces in pots or punnets and transplant them when they are big enough to handle.

Handle them very carefully to minimize the transplanting shock. Ideally you don't disturb the roots at all. Only transplant lettuce in the late afternoon to give them the longest possible time to settle in, before they have to cope with the sun and heat. If your lettuce seedlings were grown in shade or semi shade you need to sun harden them before transplanting them. Alternatively you can provide shade for a few days in their new position and then gradually remove it. A couple of hours the first day, longer the next and so on. If it's very hot, you may need to do both. The cooler the weather, the better your chances to successfully transplant your lettuce.

Growing Lettuce Plants

Lettuces need to grow fast to taste good, so keep up the water and nutrients. If the weather is very hot and your soil sandy, you will need to water daily. Stick your finger in the soil if not sure. Lettuces have a very shallow root system, so if your finger does not find any water, neither does the lettuce!

If your lettuce grows slowly despite having plenty of water, then it needs more food. Ideally you planted your lettuce in a well-prepared bed that has lost of organic matter and compost in it. If not, then you need to supply extra nutrients, especially nitrogen. The problem is that too much added nitrogen makes plants sappy and weak and very attractive to bugs. Therefore, repeated small doses of fertilizer are better than one big dose. (A classic high nitrogen fertiliser would be chicken manure.)

Lettuces need some shade in hot weather. Don't plant them in deep shade though, like under a tree. They will just grow into pale, leggy things with few leaves on them. Ideally you find a position that provides dappled shade in the afternoon. Other options are interplanting between taller plants that will not totally shade them capsicums/peppers or eggplants, staked tomatoes. Take the idea and experiment with it.

Harvesting Lettuce Plants.

For crisper lettuce, harvest in the morning. Wash leaves in cold water and dry with a paper towel. Place lettuce in a plastic bag and store in the refrigerator. Leaf lettuce can be harvested once the outer leaves reach a usable size. Picking the young, tender outer leaves will encourage the inner leaves to continue growing.

Harvest romaine and leaf lettuce as baby greens by cutting straight across the plant 2.5 to 5 cm above the soil level. Be sure to leave the basal growing point for further leaf development.

Harvest head lettuce (depending on the variety) when they’ve reached a suitable size. If you allow the lettuce to become too mature, you’ll end up with bitter lettuce.

Harvest iceberg when the head forms a tight ball, and the outer leaves are pale green. Plants can be pulled, or heads can be cut.

Romaine (cos) types of lettuce can be harvested by removing tender outer leaves or waiting until a head is formed. When removing the head, cut the plant above the base to encourage regrowth or remove the entire plant if regrowth is not desired.

Growing Lettuce in Hot Weather

Not all kinds of lettuce are created equal! Sorry, Iceberg is out. Do not bother with it. In a tropical climate it will just rot from the centre. The other hearting lettuce varieties, like Butterhead or Batavian (Summer Crisp) may do ok in the coolest months. (The upper temperature limit to grow heading lettuces is 28°C

Unfortunately, the Cos/Romaine types are also very heat susceptible. I do grow those, but they are the first to bolt to seed at the first sign of hot weather. The most heat tolerant kinds of lettuce are the open leafed varieties. All the pretty fancy lettuces you see in the shops, the frilly and curly varieties, they are your lettuce varieties of choice for hot weather.

There are also differences in the heat tolerance of the open leafed lettuce kinds. Darker lettuce absorbs more sunlight than lighter colours, so it suffers sooner (but they are prettier). Choose light green over dark red. The most heat resistant kinds of lettuce in my experience are the oakleaf varieties.

Growing lettuce in containers

Lettuce is one of the vegetables that is very easy to grow in pots and you can even grow it in a small container. Healthy and continuously productive, this crispy salad green has many qualities that make it a blessing for health. You can start to harvest lettuce in no time– about 8 weeks for most of the varieties, it is super easy to grow and productive; similar to spinach. And the best part is you don’t need a lot of space to grow lettuce.

Choosing a Pot for lettuce

Almost all the lettuce varieties grow well in pots. As their shallow roots don’t need deep soil, they do best in wide and shallow containers. The pot must have adequate drainage holes in the bottom and should be at least 15cm deep. You can use any material for pots such as plastic, clay or terracotta pots. However, if you’re growing lettuce in a container in a warm climate, do that in clay pots and plant heat resistant varieties.

Planting Lettuce in Pots

 You can easily cultivate the lettuce from seeds or from seedlings. If you want to grow it from seeds, read this post. Alternatively, you can directly buy the seedlings from a nearby nursery. For continuous harvest do successive planting, sow seeds in every two weeks throughout the growing season.

In summer, when the weather starts to heat up the lettuce tends to bolt, to reduce this tendency keep your potted lettuce plant in a cool spot and provide proper shade.

Requirements for Growing Lettuce in Containers

Spacing Considering you’re growing lettuce in a small space in your container garden, we assume you’ll harvest your lettuce plants regularly; trying “Cut and Come Again” method. This way you don’t need to care much about spacing.

Sow seeds densely and thin out the seedlings as they grow picking young, tender leaves regularly. Keep the plants 10 to 15cm apart (depending on the size of the leaves you want and cultivar). However, head lettuces require more spacing than leaf lettuces and planting depth.

Position for lettuce

The lettuce loves the sunlight (more in cooler zones) though it can be grown easily in a partially shaded area but if you’re growing lettuce in a warm climate where the sun is intense try to place the pot in a spot that receives only a few hours of morning sun.

During the hottest hours of the day (in the afternoon) it is recommended to create a shade for the plant to prevent the drying of the soil as lettuce prefers slightly moist soil constantly. Also, move the container in a cool spot when the temperature rises as this favourite green is heat sensitive.

Soil for lettuce

For growing healthy lettuce, use a good quality soil mix which has plenty of organic matter, such as compost and peat. You can also add well-rotted manure or compost additionally. The soil you use must be loamy and well-drained and doesn’t hold water too much.

Watering lettuce

In shallow pots, you may need to water frequently so that the plant will not dry out completely. Make sure that you not only keep the soil slightly moist but also avoid overwatering your container grown lettuces as overwatering can kill the plants due to root rot.

Fertilizer lettuce

Because lettuce plants mature quickly, a single or double application of fertilizer is usually all that is needed to boost the production. Before you fertilize, wait for a few weeks to allow the seedlings to establish. To fertilize lettuce, you can use a granular balanced fertilizer such as 10-10-10. You can also use liquid fertilizer for a quick boost. When fertilizing, be sure to follow manufacturer’s instructions as both over and under fertilization can be harmful.

Pests and Diseases with lettuce

Growing lettuces in containers require care from leaf eating insects. However, if the plants are healthy there are fewer chances of infestation of pests or diseases. Mildew, leaf spot, rot and a variety of bacterial infections are common diseases that can attack lettuce. In pests and insects– caterpillars, cutworms, aphids, maggots and beetles can cause damage to the plant.

Harvesting lettuce

Once the lettuce leaves have reached the height of 10 to 15cm (the baby green size perfect for cut and come again method) or according to your desired size, either pick the outer leaves individually or harvest them by cutting the leaves off 2-3 cm from above the base or crown (Must remember, don’t cut into or below the crown or else your plant will die). This way the plant will grow back, and you’ll be able to harvest it again. You can also pick the leaf lettuce before maturity, it’s simple, just remove the outer leaves when you need them in salads and keep the centre leaves growing.

Happy gardening.