How to Sow Peas: Timing, Depth, Spacing and Germination

Sow by soil temperature, not by the calendar

Pea seed germinates once the soil reaches about 40F (4C) and comes up fastest between 55F and 65F (13C and 18C). Above 75F (24C) germination collapses and the seed rots in the ground instead. That narrow window is why peas are sown either in very early spring, as soon as the ground can be worked, or in late summer for an autumn crop in mild areas.

There is also an overwintering route. Sown in autumn so the plants go into winter three to four inches (8 to 10 cm) tall, with four or five leaves, peas survive hard frost and crop several weeks earlier than spring-sown plants. Get the timing wrong and they go into winter too big and soft, and cold kills them. Sowing three to four weeks before your first expected frost is about right.

Peas are a cool season crop. Once daytime temperatures sit above 80F (27C) the plant stops setting pods no matter how healthy it looks, so every week of delay in spring is a week off the end of your harvest.

Depth, spacing and how many seeds per hole

Sow one inch (2.5 cm) deep in spring, or up to two inches (5 cm) in dry or sandy soil where the surface dries quickly. Shallow sowing in loose ground is what lets birds pull the seedlings up by the seed leaves. Space seeds two to three inches (5 to 8 cm) apart along the row, with rows 18 to 24 inches (45 to 60 cm) apart so you can reach both sides of the supports.

Many gardeners sow three or four seeds in a station every 12 inches (30 cm) instead, and thin to the strongest two. Peas actually do well in a clump: the tendrils grab each other, the group climbs faster than a single plant, and a loss to mice or rot does not leave a gap in the row. Whichever way you sow, do not sow so thickly that the row becomes a solid mat, because still, damp air inside a crowded row is what brings on mildew later.

1. Check the ground drains first Squeeze a handful of soil. If water runs out or it stays as a sticky ball, wait. Pea seed sitting in cold waterlogged soil rots within a few days and never emerges.
2. Draw a flat-bottomed drill Take out a drill an inch deep and about six inches (15 cm) wide with a hoe. A wide flat drill lets you space seed properly rather than dropping it all in a line.
3. Space the seed and cover firmly Set seed two to three inches (5 to 8 cm) apart, cover, and press the soil down with the back of a rake. Firm contact between seed and soil matters more than watering.
4. Water once, then leave it Water the drill once after sowing if the soil is dry, then do not water again until the seedlings show. Repeated watering of bare soil is the fastest route to rotted seed.

Soaking, inoculant and the things that are not worth doing

Soaking pea seed overnight is widely repeated advice and it is a poor trade. Soaked seed swells, splits its coat, and rots more readily in cold ground. If you want to speed germination, pre-sprout instead: roll the seed in a damp cloth at room temperature for 24 to 36 hours and sow as soon as the root tip shows, handling it gently so the tip does not snap.

Peas fix their own nitrogen with rhizobium bacteria, which live in most soil that has grown legumes before. On new ground, or a bed that has never had peas or beans, a legume inoculant dusted onto damp seed is worth the small cost. What is never worth doing is adding a high-nitrogen fertilizer: it gives you a tall leafy plant with few pods.

1. Pre-sprout instead of soaking Damp kitchen paper in a closed tub at room temperature. Check after 24 hours and sow the moment a white root tip appears, before it grows longer than the seed.
2. Dust with inoculant on new ground Moisten the seed slightly, shake it in the powder, and sow the same day. Direct sun kills the bacteria, so keep the treated seed in the shade.
3. Skip the nitrogen Work in compost and, if your soil is acidic, a dressing of lime. Peas prefer a pH around 6.0 to 7.0 and resent fresh manure.

Mice, birds and gappy rows

More early pea sowings are lost to mice than to weather. Mice work along the drill and take the seed before it germinates, which leaves you with a row that never comes up and no obvious reason why. Dig down where a gap is and you will find an empty seed coat or nothing at all.

The reliable answer is to start peas in a length of guttering or in modules under cover, then slide the whole row out into a shallow trench when the plants are two to three inches (5 to 8 cm) tall. It skips the vulnerable period entirely, and peas transplant well as long as you keep the rootball intact. Once they are up, pigeons are the next threat, and netting or a low cloche until the plants reach six inches (15 cm) settles it.

Write down what you sowed and where

Peas cannot follow peas. Root rot and wilt organisms build up in soil that grows legumes repeatedly, and once they do, a bed that grew a fine crop one year gives you stunted yellow plants the next. Leave at least three years, and preferably four, before peas or beans return to the same ground.

That only works if you have a record. Note which bed you sowed, on what date, at what soil temperature, and when the row emerged. After two seasons you will know your own earliest safe sowing date, which is worth more than any general guidance, and you will have a rotation plan you can trust rather than a vague memory of where things were.

1. Record the sowing date and the emergence date The gap between them tells you how cold the soil really was. A gap over 20 days means you sowed at the edge of what the seed will tolerate.
2. Mark the bed on a plan Sketch which bed took peas this year. Three years later that sketch is the only thing standing between you and a root rot problem you cannot fix.