Our gardening expert on nurturing the tart tomato relative for a Mexican salsa

How to grow tomatillos | Life and style
Tomatillos used for making salsa verde. Photograph: Rob Walls/Alamy

Last year I forgot to grow tomatillos and, come September, daily lamented my mistake. Never again; I am sowing them now. You wouldn’t expect a sour-tasting relative of the tomato to get under your skin, but once you’ve married it with lime, salt, chilli and coriander, the common tomato looks rather basic in its sweetness. Tomatillo, Physalis philadelphica, with its crisp flesh and tart flavour, is the key ingredient for a Mexican salsa, whether used raw or roasted. It works equally well as a base for soups and combines well with white beans, pork and chicken.

The first and perhaps only rule with tomatillos is not to grow too many plants or you will quickly find yourself overwhelmed with fruit. You need two plants for pollination, which is done by insects, so if you are growing them indoors make sure the bees can get in. Three plants and you’ll eat well into autumn; four and you will be bottling into December. Five plants and you might as well start your own salsa bottling business.

Tomatillos are sown just like tomatoes and are quick to germinate if the seed is fresh – within five days on a sunny windowsill or heated propagator.

The last window for sowing is the next two weeks, but you will be able to buy plug plants now from Suttons, Sea Spring Seeds and Vegetable Plants Direct. You can, of course, start them off much earlier, but I find if they get checked in cold growth when young they struggle to pick up again. The plants grow to about 30-45cm high and then they start sprawling, often leaning on the ground. The branches are fragile and break easily, particularly in strong winds.

They are not tidy sorts, but let them go as they please as any pruning tends to affect the overall harvest. Once established they are very unfussy, just don’t overwater them: they hail from South America and don’t want wet feet.

Wait for the fruit to swell in the papery husks before harvesting, they should be the size of a small tomato. There are several forms: mostly the fruit is green or purple or a mixture of both. Dr Wyche’s Yellow has purple and yellow fruit. The purple forms have a stronger sweet-sour flavour, whereas the green-yellow ones tend to be more tart.

The unripe fruit of either variety is very tart, but well worth experimenting with – it’s nice thinly sliced in salads. I think the best salsas are a mix of tomatillo and tomato, the acid-sugar balance compliments each ingredient in such a pleasing manner. The plants often get weighed down by harvest, and fruit that sits on the ground will get munched by slugs, so get in there first.

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