Perhaps it is no wonder that St Valentine’s Day has become a celebration for lovers. In London it is the day when we finally have ten hours of daylight. Contrary to popular belief it is day length, and not temperature, that will trigger most plants into spring growth.

American land cress in box.
American land cress needs loads of water, but will grow in low light levels. It has a spicy flavour like watercress, but unlike watercress it doesn’t need running water to thrive. Photo: Wendy Shillam, Rooftopvegplot.

We get very few frosts here in Fitzrovia. If you have a sunny windowsill, think Mediterranean – try red basil, rocket, even a few tomatoes (which can be started off this month inside). But if your space doesn’t get sunshine you can still grow leaves like lettuces, mint, American land cress and red mustard.

Don’t bother to buy special seed trays or pots. Your plants will soon become the decorative feature and hide any old plastic tray you can find. Salads will grow in shallow soil, just 1 inch or 2.5cm of good quality, all-purpose compost, is enough.

Some supermarket trays make excellent pots, especially the ones that come complete with a domed plastic lid, that acts like a greenhouse. It can be quite windy on a high terrace or windowsill, so a bit of protection is useful in the early stages.

Sprinkle seeds generously onto pre-wetted soil. Ignore any spacing advice on the packet, (which is aimed at a main crop). Lay a sheet of newspaper on top of the seeds until they germinate, or sprinkle with a little soil and cover with a plastic top, to keep the soil moist.

All pots will require drainage. Make a few holes in the base with a pair of scissors and set the pots on a tray of gravel, to catch the drips. If you are growing inside, the moist gravel will provide a more humid microclimate than the room.

As the seeds start to appear, use a pair of nail scissors to thin them out. Don’t throw away the thinnings. This is highly prized micro-veg. The first two leaves, called cotyledons, have tons of goodness in them. Micro-veg makes an excellent garnish for a salad or a sandwich. And this little crop will come within two weeks – so it’s a very early win!

As they grow you can ‘mow’ a punnet of fresh leaves, like cutting hair, to produce enough for a salad. Leaves will re-grow as long as you don’t pull out the roots, or cut out the heart of the plant. Alternatively you can continue to thin out the seedlings, giving more space for a few larger plants to develop.

It’s worth leaving a strong basil plant to grow into a bush. Simply transplant it into a bigger pot. But cresses, mustard leaves, lettuce and spinach are best cropped regularly to keep the leaves fresh and succulent.

What really tastes good? I recommend coloured varieties. They look pretty, taste better and have more valuable nutrients. There is a list of my favourite seeds for salads on my website

Wendy Shillam is running a series of workshops at her rooftop garden in Fitzrovia this spring where she’ll be sharing her urban gardening skills and cooking tips. For more information and to book, visit the Spring Workshops page.