Growing lettuce can be a simple and rewarding task, with fast results and a tasty fresh crop.
Lettuces grow well in cooler climates and are particularly well-suited to the UK and other cooler areas.
You can grow them in containers successfully as well as grow-bags and, of course, directly in the ground. Growing them in containers is a great option because you have a lot more control over the growing conditions and they are much less susceptible to pests such as root aphids, slugs, and snails.
Lettuces prefer cooler climates and do not like to be in direct sun, so find a shady area to grow them.
They also like to be kept moist at all times.
They usually have a very narrow harvest window of about a week, so it’s important when growing lettuce not to plant too many all at the same time or you will get a glut and end up giving/throwing them away. Sowing them every couple of weeks throughout the growing season is a good system to have in place.
Lettuces need to be grown quickly in good conditions. If they are grown in poor soil or have to hunt for nutrients, the extra time delays will cause their leaves to get tough and leathery.
Types of lettuce
There are four main varieties of lettuce, each of which has many different styles of plant.
Crisphead – Leaves tightly packed together – grow best in cooler weather.
example plants: Webbs wonderful, Avoncrisp, Iceberg, Great lakes, Raleigh
Butterheads – Tend to be smaller in size – looser, more tender leaves.
example plants: Tom thumb, Nancy, Buttercrunch, Winter crop.
Loose Leaf Lettuce – Fastest growing – single leaves can sometimes be cut from the plant while it grows (like a herb). Most popular among kitchen gardeners.
example plants: Salad bowl, Grand rapids, Green ice.
Romaines (or “Cos”) – Normally the leaves are tightly packed together. Darker green – almost cabbage-like Rigid leaves.
example plants: Green towers, Parris Island, Valmaine.
Growing lettuce requires good quality well-drained soil that retains moisture well. Something like Mel’s Mix from the square foot gardening method would be ideal. Getting the soil to err slightly towards the ericaceous (acidic) side with a PH of 6.5 – will provide the perfect growing conditions for growing lettuce, so if growing lettuce in a container, throw in a handful of ericaceous soil and mix it in well.
Because lettuces are fast-growing crops, you can help maximize your yields by growing a catch crop. Plant a few lettuce seeds in amongst your other slower growing plants such as broccoli. The lettuces will not take too many nutrients from the soil but will provide you with an extra crop from the same growing space.
Lettuce seedlings will not be happy if you transplant them, so sow them directly into the ground or into the container you intend to grow them in wherever possible.
If you want to start them off early indoors on a windowsill, it’s possible, but sow the seeds into peat pots or cardboard egg boxes, that way when you come to plant the seedlings, you can plant the whole thing – pot and all – and you will not disturb the roots.
Place a couple of seeds into 1/2 inch deep holes about 6-10 inches apart (depending on the variety of lettuce you are using). Germination only takes a week or so. If both seedlings germinate, snip off the weaker one when the first proper lettuce leaves begin to appear, so you are left with one healthy seedling per 6-10 inches.
If growing lettuce outside, watch out for the birds who’ll find your seedlings a succulent snack
It takes between 8-14 weeks from planting to harvesting for the crisphead, butterhead and cos varieties, or about 8 weeks for looseleaf varieties.
Caring for your growing lettuce plants is very simple. Just keep them watered. If you are using good soil, you will not even need to feed them. Water them in the morning to lessen the risk of disease, and prevent the lettuce drying out during the day. Keep them weed-free and un-cluttered to discourage the slugs.
This is when the need to sow a small number of seeds once every two weeks becomes apparent. The ‘harvest’ window for lettuce is very narrow. You have about a week from the time the lettuce is ready to pick; to the time it begins bolting. Once the heart of the lettuce has formed, it’s time to pick. If you don’t, the heart will start to grow upwards at which point a thick stem will appear and the lettuce will go to seed.
When harvesting, remove the whole plant to discourage rotting and disease in the ground where it grew.
Slugs and snails are your main obvious enemy, but lettuces are also prone to several issues including mildew and mold – which most usually occur during dull damp summers. To treat, remove the affected leaves as soon as possible and spray them with a protective fungicide such as Dithane.
Greenfly is also another issue that could affect your lettuces. These are very common, and excrete a sticky substance onto the plants (called honeydew), and also transmit viruses. These are also a particular issue with tomatoes, strawberries, and cucumbers and they can spread from one plant to another – something to be aware of if you are growing several of these plant types on close-proximity to each other. Fortunately, the greenfly has a number of natural predators such as the ladybird, lacewing larvae, and a number of wasp species, but they also have some allies. Some species of ants actually ‘farm’ greenfly, and consume the honeydew they produce and will protect them from their natural predators. Soapy water sprayed onto the plant will remove the greenfly, but will not kill them, so they will keep returning. It appears the only way to deal with them permanently is with chemicals.
A more serious issue can be root aphids. These tiny cream-colored bugs can be devastating to your lettuce and any affected plants must be destroyed.
It’s important not to put the diseased plants onto the compost but throw them away, the same goes for the soil if you are using a container, otherwise, a chemical spray is your best hope. See what’s available in the garden center.
Adding sand and crushed eggshell to the area surrounding your lettuce will put-off slugs and snails from attempting to reach them. Also trying to encourage frogs and toads to your garden will keep the slug population in check.