When To Sow: April-May (with protection); May-July (direct seed) Harvest: June-September
Germination: 7-14 days Full Sun
This family of beans is frost tender and cannot be sown until the weather has warmed up. Your best bet is to sow dwarf french bean seeds in pots in a greenhouse in April for planting out in May as your first crop.
Starting Indoors: For the earliest crops, sow the seeds inside no earlier than April. Sow single beans 4cm (1.5”) deep, in root trainers or into 7.5cm (3”) pots filled with multipurpose compost. Plant out in May when the soil has warmed and all risk of frost is past (harden plants off plants gradually). 20 cm between plants.
Direct Seed: In late May, sow in double or single rows or in blocks. Plant the seeds about 4-5cm deep and 20-25cm apart. Space the double rows 20-25cm apart and leave 60-80cm between two double rows, this way the plants protect each other from the wind. Or sow the broad beans in single rows, leaving about 40cm between the rows. Water well.
Plant in well-worked soil and/or compost that has already been well-watered. We like to plant ours in blocks to provide support and good pollination, usually in a 5 grid (like no.5 on a dice). Water well until plants are clearly well established. Start picking when pods are about 10cm long and snap if you bend them. Harvest regularly – the more you pick the more they’ll produce!
Dwarf french beans have shallow roots and therefore need regular and plentiful watering. They prefer being watered particularly heavily when the flower buds appear and once they're open--twice a week in dry weather. Mulch to help with water retention.
Maintenance
If growing outside, water only when needed--at the start of the seedling growth and once flowers have formed. They should be fine from here on out unless there is a drought (unlikely in our British winter weather).
As with other broad beans, you can pinch out the growing tip once lower pods have formed to deter black flies. (Some of us wait until we see the blackfly first, but if you want to be preemptive, do it sooner.)
These beans are especially subject to predation by slugs and other garden pests. If you know you have a slug problem, start the beans in modules first to give them a head start, planting out when they hit 9cm tall.
Sowing in two-week intervals will ensure a continuous supply and longer growing season (successional sowings will also help out if early plantings get taken out by slugs).
Harvesting
Dwarf french beans are best picked young when they have a sweeter taste. This can be as early as when the pods are tiny and pointing upwards on the stems or once the pods start to swell and the seeds become visible as bumps (when they start pointing downwards). Picking early also encourages further pod production. Waiting longer to harvest will produce tougher skins and a wooly texture in the mouth. (If you end up with older beans and aren’t looking to collect them as seed, try blanching them for a minute or two in boiling water and then squeezing the seeds out of their bitter coats.)
They require only a brief cooking time (steaming is best) and do well-served whole. Harvest when totally dry if seed saving or storing dry. Once harvested, leave the roots in the ground and/or lightly till in the stems to allow the nitrogen-fixing nodules can fertilize the next crop.
Companion Planting
Dwarf french beans are a part of the nitrogen-fixing legume family of plants. Use anywhere you’d like to add nitrogen to the soil. They combine well with corn, squash, lettuce, kale, spinach, and other greens. They’re not fond of the allium family (garlic, onion, chives, etc.).