There are many rewards to be had from growing food in containers, but getting a worthwhile harvest from a small space can be a challenge. My first attempt at balcony growing resulted in one solitary serving of rocket. Fortunately, it’s possible to get a year-round supply of fresh vegetables and leaves from your pots: the key is planning.
There’s plenty to be learnt from historical examples of urban farming. In the Nineteenth Century, before refrigeration and national rail networks, vegetables had to be grown locally if they were to be eaten fresh. To meet the high level of demand in cities, urban farmers developed ingenious ways of growing food intensively on small plots of land. As well as copious supplies of manure, the big secret of their success was planning. They knew exactly how long each crop took to mature. Then, when harvested, the space would immediately be filled by another crop, carefully grown to be ready to plant out just in time. In the suburbs of Paris, the French farmers became masters of this technique. They regularly managed to grow five or more crops on each bit of land every year.
French Intensive Farming, as it became known, is a highly skilled business. But growing three or more different crops in a container per year is not difficult. The trick is to start the year by growing a crop that matures early, following it with a main crop over the summer, and then replanting the pot with autumn and winter crops.
Peas are one of my favourite early-maturing crops. If planted in February or March, they’ll be ready by June or July when they’ll make a welcome addition to the dinner table, singing of summer on its way. (I’ve found that mange tout or snap-type peas give significantly better yields from containers than podded peas.) First Early or Second Early potatoes also grow in just three months, ready for harvest in June or early July. Although potatoes take up lots of space, they taste so much better than shop-bought that it’s hard to resist growing a few. Other crops you can harvest in June or July from a March sowing include mini beetroot (ten to twelve weeks to harvest), chard (ten weeks), carrots (fourteen weeks) and turnip (eight weeks).
Your choice of your first crop of the season will be influenced by what you want to grow next. Even peas and Early potatoes will not be ready in time if you want to plant your tomatoes out before the end of May. In this case, your alternative is to choose an even faster-maturing crop, or ‘catch crop’, to start the year. Good early season catch crops for containers include radishes (three to four weeks to harvest), pea or broad bean shoots (two to four weeks), rocket (six to eight weeks), coriander (six to eight weeks), and many of the Asian greens like pak choi, Chinese cabbage and choy sum. Started under cover in February or outside in March your crop will be ready to harvest by April or May.
As your first crops of the year mature, you can save further valuable space and time by starting the next set of crops in seedling trays or small pots. This means that when your first crop has been harvested, you can immediately replace it with a seedling or small plant.
Your second crop will usually be your main one of the year. Tomatoes, aubergines, and peppers ideally need to go in before the end of May. Courgettes, squash, French and runner beans, on the other hand, can be transplanted as late as the end of June, even mid July if started first in pots. Carrots, beetroot and spring onions can be sown in July – sow direct or raise in modules because root vegetables do not like their roots disturbed.
August and early September is the time to start sowing your third crop in trays or pots, ready to go into the container when the second crop has finished fruiting in late September or October. The idea is to get your third crop well established before the coldest months set in – this will help it to survive the winter. Good winter crops for containers include kale, chard, cavolo nero, mooli, and winter salads like lamb’s lettuce, winter purslane, winter lettuce, and land cress.