Learn how to grow lettuce - it's easy really!
Picture: Lettuce seedlings growing in a planter in the greenhouse
How to grow lettuce: Argh - the problems!
Growing lettuce is amazingly easy but good results can be dependent upon the weather - and some good management. Too hot and your precious crop wilts or becomes dried out and not very nice to eat. Too cold and wet and your lettuce plantings may struggle to grow, or be attacked by slugs (ugh!).
Most of the time though, it is easy to grow lettuce successfully. You just have to stick to a few simple guidelines. So here's a brief guide to how to grow lettuce and how to avoid the pitfalls.
Growing lettuces from seed on a window sill or in a greenhouse is easier than starting them off in the garden. That way they don’t have to compete with weed seeds and the slugs can’t get them.
As long as you remember to keep them damp and check that they are not too hot or chilly, they can get off to a flying start.
You also need to avoid over-crowding - so scatter the seed thinly.
If all this seems too much, buy seedlings as small plug plants and follow the instructions for transplanting given below.
Picture: Crisphead seedlings and an oakleaf lettuce
Use a seed tray which is deep enough to carry at least 3 cm of soil or more and fill it nearly to the brim with compost. Leave about 1 cm gap between the top of the container and the compost.
The best compost to use is seed compost but ordinary multi-purpose compost will do. I usually use peat-free compost these days as they are much more environmentally friendly. This is available in most garden centres.
Peat-free composts tend to be a bit more expensive and can be tricky to work with, especially for seedlings. But they are far more eco-friendly than peat based products because peat comes from irreplaceable peat bogs which are often home to rare birds, flowers and other wildlife.
Non-peat composts are improving all the time, too, so there is really no real reason to keep on using peat-based ones.
You can also use your own homemade compost or even carefully sieved soil. You will find it much harder to avoid competing weed seeds if you go down this route. For the sake of the price of a bag of seed compost for your seedlings, I believe it's far less trouble to use a professional product.
Scatter the seeds across the surface of the compost.
The easiest way to do this is to take a pinch of seeds between thumb and forefinger and sprinkle them much as you would sprinkle salt on food. (Gently, though - you don't want to break them!)
Remember to sow thinly for best results; over-crowded seedlings will have to fight for space and light as they grow and may succumb to fungal infection ("damping off").
Cover the seeds with a thin layer of compost. Firm the compost down gently. If the compost is not damp already, then water it thoroughly, but not so much that it is sopping wet - the seeds will rot in conditions that are too wet.
Now cover your seed tray with cling film or even just with paper. Put the seed tray where it can drain freely.
Check every day to see whether the seeds have germinated and to make sure the compost is still damp. Cling–film is wonderful for helping to keep moisture in. It isn't the most eco-friendly stuff though, so you might want to recycle old discarded plastic wrappers or even use paper.
Water as needed with a fine spray or carefully dribble water on around the emerging seedlings. Once the seedlings are big enough to touch the cling-film or plastic it is time to take it off. If you used paper, take it off as soon as a few seedlings are showing.
Planting lettuce seedlings out throughout the season can give you lettuce available for a good part of the year – even into winter. Choose two or three varieties to sow each season so that you don’t get bored.
Some lettuces are more suited to autumn sowing; others cope better with summer heat, so choose appropriate ones for your climate and the time of year. Start new trays of seed off about every two to three weeks throughout the season for continuous crops.
For some good alternatives to lettuce see here.
For one of the best and most comprehensive guides to growing salad materials see Salad Growing by Joy Larkcom
When the seedlings are about an inch high (2-3cms) you can transplant them into their growing positions. Don’t leave them to get much bigger as they become floppy because they haven’t enough room in the seed tray to grow properly. (The ones you buy in garden centres and the like are often already too big and wilt dramatically as soon as you plant them out.)
Use a pencil, a small pointed stick or your fingers to gently pry them away from their neighbours in the tray. Take as much compost as you can with the roots – this will help them to get established quickly in their new positions.
Make a hole quite a bit larger than the root mass of the lettuce (sometimes the roots are stringy little things if the soil falls off but don’t worry). Lay the plant in the hole with the leaves poking out over the top of the hole. Pour water into the hole until it is swimmy with mud and then gently fill in the soil around the roots.
Press the soil down gently but firmly to make sure that the roots are making good contact. That way the roots are ready to carry on working, pulling in nutrients and helping the plant to grow. If the plant flops over onto the soil then shore it up with more soil tucked around it. (If you plant out your seedlings when they are the right size – not too big – then this does not usually happen.)
It is best to transplant lettuces when the weather is neither cold nor too hot. Choose mild dampish weather for preference. Check them for the first couple of days to see that they are establishing themselves and not wilting.
If you need to water them, do it carefully and thoroughly, but not so much as to risk dislodging their roots.
When you have covered the area with seeds you then rake it gently to settle the seed into the ground and firm it down. When the crop comes up you need to pull any competing weeds and make sure that there is enough moisture in the soil for all. That said, if your soil is rich with organic matter the seedlings will cope with most normal weather in temperate areas.
It can help to give them a really thorough watering a few days before you start picking leaves. This helps to make them more succulent and juicy. Planting lettuce this way can be done using containers or even large pots – you just need to remember to water them enough.
To prevent lettuce from bolting in hot weather (after all, most of us don't want to be eating lettuce soup in the middle of summer!) you may need to provide some shade and resign yourself to a certain amount of watering. Dappled shade is best, as provided by willow screens, for example. It is also helpful to provide good, rich soil with plenty of organic matter - you can do this by using mulches, of compost, leaf mold, or other organic matter.
"Cut and come again" lettuce is easy to grow and you end up with an almost continuous supply for weeks on end. Growing lettuce as a cut and come again crop is perhaps the very easiest lettuce growing method.
In this method you prepare some ground carefully by hoeing and raking in the usual way. Then you sow the seed by broadcasting it. This means that there is seed all over the patch, fairly evenly distributed. You do this by taking small handfuls of seed and carefully throwing them in an arching motion over the nearby soil. Your hand needs to be only a few inches from the soil and when one part is covered you move to the next area. It’s all in the wrist action! (This is like the way seed was sown years ago for large crops such as wheat.)
Cut and come again lettuce can also be sown in large containers or pots.
Once the crops become large enough you can snip off leaves for the table whenever there's enough growth available. The lettuces stay almost like seedlings but keep on re-growing again and again. It is important not to cut any one seedling too drastically; you want it to resume growing without being damaged. Take no more than a third at a time is a safe rule of thumb.
You can buy special cut and come again lettuce seed. The selected varieties do particularly well as seedling crops, i.e. they never need to reach full maturity but produce tasty small leaves abundantly. You can also buy seed which is mixed with other salad leaves, such as mizuna or rocket.
Baby salad leaves are often more acceptable at the table than large chopped leaves - and they are easier to produce to a good standard.
To harvest the leaves, use scissors or carefully twist off leaves without disturbing the roots. New leaves will quickly grow to replace the ones you harvested and you can crop them again. As noted above, it pays to be moderate in the amount you take at any one time.
If you let a few of your best plants run to seed, there will be new seedlings to collect from beneath the dying plants in the autumn. This can be quite an easy way to begin new crops. Just choose the strongest young plants and transplant them into new growing positions, as needed.
You can also save some of the seed for next year. This only works with plants grown from non-F1 hybrid stock. F1 hybrids do not reproduce reliably.
Gather the seed heads on a dry day in a dry spell. Store seeds loose in a paper bag in dry conditions. Don't forget to label them with variety and date collected.
If you study how to grow lettuce in different ways and gradually refine and adapt the methods you like most you can have tasty crisp lettuce leaves for your salads practically all year.
Lettuce are notorious for bolting (running to seed) just as you want them. This is especially true in hot weather. You can use these lettuce tops in soups and stews quite successfully.
But should you want more lettuce without the trouble of starting from sowing seed, try this. When you use a lettuce, rather than pull it out with its root, cut it off and leave the base of the plant in the soil with a few of its outermost leaves attached. You will find in many cases that a few weeks later you have two or three new, smaller (but perfectly formed!) lettuces springing up from the old root. These are just as crunchy and delicious as the original lettuce.
This works best early in the season and works better with some varieties than others.
Please note: It's generally better to just start off sowing more seeds but it's an option that could work if you realise you've just not sown enough! Plants left in the ground too long can harbour diseases, so this is not something to do for too long. If they look sickly or leggy, or are attracting slugs and other pests, pull 'em up and start again with new soil or compost.
Other pages related to how to grow lettuce that might interest you:
- an occasional e-zine from Greenfootsteps
If you would like to receive the e-zine, please just sign up below.