Lettuce is a common vegetable, the basis of many salads: Caesar, Waldorf, even the humble ‘garden salad’. In fact, in some parts of the world, the plant itself is called ‘salad’.
How many varieties of lettuce can you name? For many people, it would be the five commonly sold in the supermarket: Iceberg, Cos, and the hydroponically grown leaf lettuces: Salad Bowl, Oakleaf and Buttercrunch.
It may surprise you to know that at the end of the 19th century, there were over 1,000 named varieties of lettuce known around the world. Many of those no longer exist, or have been replaced by F1 hybrids, but there are still a lot more varieties available than you will see in a visit to the supermarket, the green grocer or even the Sydney Produce Markets.
Here, in our Emu Heights garden, we grow our lettuces from seed. Right now, we have ‘Australian Yellow Leaf’, ‘Frilly Pink’, ‘Marvel of Four Seasons’, ‘Michelle’, ‘Rabbit Ear’ and, our most prolific through winter, ‘Cos Verdi’ and ‘Regina della Ghiacciole’. We pick all our lettuces as ‘cut and come again’ greens, even though some of them are Cos or crisp-head varieties.
In a colder climate, ‘Regina della Ghiacciole’ should form an iceberg-style heart but the climate is too mild here – and our constant pickling of the outer leaves doesn’t help! The photos below show lettuces that have been picked regularly, some more recently than others.
The botanical name for lettuce is Lactuca sativa which, like many Latin names, is descriptive of the plant itself. Lactuca, from the Latin word for ‘milk’, refers to the white sap that is apparent in fresh lettuce leaves when cut or broken. Unlike many other plants that exude a white sap, lettuce is not toxic to humans but can be to dogs. The word ‘sativa‘ is applied to many plants and refers to them being cultivated, as opposed to being gathered from the wild. It is believed that lettuces were in cultivation by the Ancient Egyptians. That means that the cultivation of lettuce as food or medicine has been around for over 4,000 years – an heirloom (or heritage) vegetable indeed!
HOW TO GROW LETTUCE
You could grow lettuce from seedlings bought at the garden centre but the range is limited. If you want to grow more unusual varieties, starting from seed is the way to go! Lettuces are fairly easy to grow from seed, if they are given the right conditions. They need a loose, fluffy seed raising mix. The must be kept moist but not saturated; baby lettuces are easily ‘suffocated’ (drowned) by too much moisture and not enough air in the growing medium.
Being soft-leafed, lettuces are susceptible to ‘damping off, a soil borne fungal disease that attacks the stems at the soil level and causes them to rot overnight. To counteract this, lightly sprinkle cinnamon on the surface of the soil. This inhibits the growth of the fungus that causes the disease. Tender soft leaves are also a magnet for slugs and snails, so try to grow your plants in pots until they are big enough to fend for themselves in the ground. Put copper tape around your pots – the slugs and snails will not move across it. We cut the bottom off old pots and put copper tape on the outside – we then put these, in the garden, around our susceptible small plants as ‘collars’.
Wild forms of lettuce were originally found from the shores of the Mediterranean to the steppes of Siberia. This would indicate that lettuce had a wide range of growing conditions and that it tolerates cold quite well. The Mediterranean climate is made up of hot, dry summers and cool wet winters. This shows that lettuce is not good in hot weather (there are some exceptions), so plant your spring and summer crops on the east side of the house, a shed, fence or trellis and make sure they have plenty of moisture – those soft leaves will dry out quickly and may not recover. You could also try growing lettuce inside in summer, keep plants away from the air-conditioner vents as the constant movement of air can dry out the leaves.
You can start harvesting leaves when the plants are about 10-15cm across but always leave the growth point at the very centre of the plant intact. If you want a hearting lettuce, stop harvesting leaves as soon as you see the heart beginning to form. In general, hearting lettuces, especially those of the crisp-head (iceberg) varieties, are cool weather crops.
FUN FINAL FACT
Lettuce are members of the Asteraceae family, which includes sunflowers, chrysanthemums, daisies and dandelions. The white sap exuded by lettuce when cut or broken is a form of latex!
DISCLAIMER: The information given here is for entertainment and/or gardening purposes only. Please do further research if you are unfamiliar with this plant. If you have never eaten it before, try a leaf and wait a few hours before eating more.