Oca
Oxalis tuberosa
Oca (New Zealand yam) is a fantastic alternative to potatoes — blight-proof, pest-free and producing colourful pink, yellow or red tubers with a lemony tang. Plant tubers in April or May, 10cm deep and 30cm apart, in moist fertile soil. The clover-like foliage grows slowly all summer, then explodes after the autumn equinox; tubers only form in short day conditions, so don't be tempted to lift early. Earth up like potatoes in late summer to increase yield. Harvest after frost has killed the tops — usually November or December. Cure tubers in sunlight for a week to sweeten them and reduce oxalic acid. A brilliant low-maintenance crop perfect for organic plots.
When to Sow Oca
Sow oca in April, May.
Time to Harvest Oca
Expect to harvest approximately 7 months after sowing.
Companion Plants
Expected Yield
Yields 0.5–1kg of tubers per plant from a late harvest.
Common Problems with Oca
Poor yield from early harvest
Tubers only swell in October and November. Wait until frost blackens the foliage before lifting — patience doubles or trebles the crop.
Sharp, sour flavour
Fresh oca contains oxalic acid. Sun-cure tubers on a windowsill for 7–14 days after lifting to sweeten dramatically.
Frost killing tops too early
Tops are tender but tubers are safe underground for several weeks. Mulch heavily with straw if hard frost threatens in October before tubers have bulked up.
Plan your oca in the allotment planner
Drag and drop plants onto your plot and get personalised sowing reminders.
Open PlannerMore Vegetables
Cherry Tomato
Solanum lycopersicum var. cerasiforme
Cherry tomatoes are one of the most rewarding crops for UK allotment growers. These small, sweet fruits ripen reliably even in cooler summers, producing heavy trusses from July right through to October. They thrive in grow bags, pots, or directly in the ground, making them versatile for any plot size. Pinch out side shoots regularly on cordon varieties to channel energy into fruit production. Bush varieties like 'Tumbling Tom' need no training and work brilliantly in hanging baskets. Feed weekly with a high-potash tomato feed once the first fruits set. The key to great flavour is letting them ripen fully on the vine rather than picking early.
Beefsteak Tomato
Solanum lycopersicum
Beefsteak tomatoes produce the large, meaty fruits that are perfect for slicing into sandwiches and burgers. They need a long growing season in the UK, so starting seeds early under cover is essential. These are almost always grown as cordons — train them up a single stem, removing side shoots weekly. Each truss produces fewer but much larger fruits than cherry types, often weighing 200–500g each. They benefit from greenhouse growing in cooler regions, though sheltered outdoor spots in the south can produce good results. Consistent watering is critical; irregular watering causes blossom end rot and fruit splitting. Stop the plant at 4–5 trusses to ensure fruits ripen before autumn.
Nantes Carrot
Daucus carota
Nantes carrots are the gold standard for flavour — sweet, crisp, and cylindrical with a smooth skin that barely needs peeling. They perform well in most UK soils but prefer light, stone-free ground to grow straight. If your soil is heavy clay, grow them in raised beds or deep containers filled with sandy compost. Sow thinly to avoid the need for heavy thinning, which attracts carrot fly. Cover rows with fine mesh or enviromesh as a physical barrier against carrot fly — this is far more reliable than companion planting alone. Successional sowing from March to July gives you carrots from June through to winter. Late sowings can be left in the ground over winter under a thick mulch of straw.
Butterhead Lettuce
Lactuca sativa
Butterhead lettuce produces soft, rounded heads with tender, buttery-textured leaves that melt in the mouth. It's one of the quickest salad crops to grow — ready in as little as 8 weeks from sowing. Unlike iceberg types, butterheads tolerate partial shade and are less likely to bolt in warm spells. Sow small batches every 2–3 weeks from March to September for a continuous supply. They work well as an intercrop between slower-growing vegetables like brassicas and leeks. Water consistently but avoid wetting the leaves to reduce the risk of grey mould. 'All the Year Round' is the classic UK variety and lives up to its name, performing well in almost every season.