SOWING: Seeds can be sown as soon as the soil can be worked in the spring. Some people try to push the season even earlier by sowing in flats indoors and transplanting, but we are not those kinds of people (peas don't love to be transplanted). Direct seeding is strongly recommended. Note: fully saturated cold soil can cause big fleshy seeds like peas to rot, so waiting for a dryish spell in regions that see a lot of precipitation in the early spring (like here in the PNW) is recommended for good emergence.
PLANTING DEPTH: 1/2-1"
SPACING: 6-8 seeds per linear foot (thinning further is not generally needed)
EMERGENCE: 5-14 days @ soil temp 50-75F
LIGHT: Full sun to part shade
FERTILITY: Low to medium. Peas (and other legumes) are able to produce their own usable nitrogen from atmospheric nitrogen through a symbiotic relationship with bacteria that colonize specialized nodules in their roots. Too much soil fertility can cause excessive vegetative growth at the expense of pod set. High nitrogen can also produce more disease susceptible plants.
ADDITIONAL NOTES: Climbing varieties to 3' or higher should be trellised with wire fencing or hemmed in with twine stretched between vertical posts for support. Dwarf varieties can be grown in strips to "self support".
It can be quite beneficial to mix pea seed with commercially available bacterial "inoculants" to encourage the beneficial symbiotic relationship in the growing plant's root nodules, especially if growing on ground that hasn't been planted with peas before. They can increase yields and improve plant health. In gardens or fields where peas have been grown regularly, there are often adequate populations of the beneficial bacteria already present and inoculant isn't necessary.
Packet sows approx 6-8 ft