Sow peas about 4 weeks before your last frost, once the soil reaches 45°F, 3 inches apart in rows 24 inches apart, and harvest in 55 to 70 days. Vining types need a six-foot trellis. Good companions are carrots, radishes and cucumbers; keep onions and garlic out.
Trellising peas
Peas climb with tendrils, not twining stems, which decides what works as support. A tendril wraps around something thin — netting, string, wire mesh, twiggy prunings. It cannot grip a smooth post or a wide plank.
Match the height to the type. Dwarf and bush varieties reach two to three feet and manage with light support or a row of twiggy sticks. Vining varieties reach six feet or more and need a full trellis; without one they sprawl into a mat that rots from underneath and is miserable to pick.
Put the support in at sowing. Peas grab whatever is nearest within days of emerging, and installing a trellis over established plants damages them.
Practical options, in rough order of how well they work in a home garden: pea netting stretched between two posts is the standard and the easiest to pick through; string wound between posts in horizontal courses is cheap and works well; a wire mesh panel lasts years; brushwood stuck in the row is free and traditional and suits dwarf varieties.
Run the trellis north to south where you can, so both sides get light through the day.
Pea inoculant
Peas are legumes and can fix their own nitrogen from the air, but only in partnership with Rhizobium bacteria that colonise their roots. Inoculant is simply those bacteria as a powder, mixed with damp seed before sowing.
Whether it is worth using depends on the bed. Soil that has grown peas or beans in the last few years already carries the bacteria, and inoculant adds little. Ground that has not — a new bed, a new garden, a container of bought mix — may have none, and there the difference is real: plants without their partner have to take nitrogen from the soil like any other crop, and grow accordingly.
It is cheap, it is applied in seconds, and the downside is nothing but the cost. Use it in new ground; skip it in an established rotation if you prefer.
The nitrogen mostly stays in the plant, which is worth knowing. Peas do not enrich a bed much while growing — the nitrogen is in the roots and top growth, and is released when those break down. Cut the plants at ground level and leave the roots in, rather than pulling them, to get the benefit. How to add nitrogen to soil covers where legume fixation sits against the alternatives and how long it takes to become available.
Pea companion plants
Good neighbours, and why.
Carrots and radishes are the standard interplanting, and it is a space argument rather than a chemical one: both are narrow root crops that occupy the ground under a trellis without competing for the light peas need. Radishes are up and gone before the peas fill out.
Cucumbers and spinach appreciate the light shade a pea trellis casts, which is a genuine benefit in late spring when spinach would otherwise bolt.
Anything that follows peas gains from the nitrogen left in the roots. Peas make a good preceding crop for a leafy one.
Bad neighbours, and why.
Onions, garlic, leeks and shallots. The allium-legume exclusion is one of the most consistently reported in companion planting, and peas are the more sensitive partner. The mechanism is not established — it is repeated far more often than it is explained — but the advice is uniform enough to follow. Whether companion planting actually works covers how to weigh a claim like this.
Spacing and when to plant
3 inches between plants, 24 inches between rows.
Peas are sown densely — they are narrow, they support each other, and a thick stand climbs better than a sparse one. A double row either side of a single trellis is the efficient layout. The plant spacing calculator will work out seed numbers.
Sow about 4 weeks before your last frost, and use soil temperature as the real trigger: 45°F is the point at which pea seed germinates reliably. They are a genuinely cool-season crop, germinating in cold ground and shutting down in summer heat, so early sowing matters more here than for almost anything else. The planting date calculator gives the frost-relative date.
Do not start peas indoors. They grow fast, resent root disturbance, and a transplanted pea gains nothing over one sown direct a fortnight later.
An autumn sowing for a spring crop works in mild areas, and a late-summer sowing can give an autumn crop where the first frost is late.
Growing in containers
Peas do well in containers, particularly dwarf varieties. Allow 10 to 12 inches of depth, and sow at the same 3 inch spacing across the surface.
A container still needs a trellis unless the variety is genuinely dwarf. A tomato cage pushed into a large pot works well.
Watering and feeding
About an inch a week, and consistently once flowering starts — pods fill poorly in dry soil.
Do not feed nitrogen. Peas make their own, and added nitrogen gives lush foliage and fewer pods. This is the opposite of the advice for most vegetables and catches people out. Phosphorus and potassium are fine.
Pea flowers and pod set
Pea flowers are white or purple and largely self-pollinating, so they do not depend on insects.
Heat is what stops pod set. Above about 80°F flowers drop rather than developing, which is why a sowing made too late so often flowers beautifully and yields nothing. A cold wet spell during flowering causes a temporary version of the same thing.
Neither is correctable mid-season. The answer is always the sowing date.
Harvest
55 to 70 days, and the type decides the signal.
Shelling peas are ready when the pods are well filled and still bright green, and they go starchy within days of that point. Snap peas are picked when the pod is plump but still crisp. Snow peas are picked flat, before the peas inside develop at all.
Pick every day or two once they start. Peas convert sugar to starch quickly after picking, which is why home-grown peas taste so much better than shop ones and why they should go from plant to pot fast.
Picking keeps them producing. A plant allowed to mature a few pods fully stops flowering.
Common problems
Poor germination in cold wet soil. Peas germinate cold but rot in cold and wet. Wait for 45°F rather than sowing into mud.
Flowers but no pods. Heat, covered above.
Powdery mildew late in the season. Common as the weather warms and the crop finishes. Improve airflow, water at the base, and accept that a spring crop ends around the time it appears.
Birds and mice taking seed. Both take pea seed readily. Netting, or starting in a covered row, solves it.
Peas make good use of the ground beside carrots and should be kept well away from onions.