The answer depends on where in the world you are gardening and on the conditions in your vegetable plot. Also you need a lot of pea plants to get a reasonable quantity of peas so direct sowing is a lot less labour intensive.

Are you saying that you now have pea seedling growing indoors? or just planning to start them inside? If the latter I'd wait to plant the seed directly inground for your area around late March or early April if the hard freezes are behind you. Peas are pretty tough and can handle cold snaps in the mid/upper 20's ok. Here in Va I'll be planting my seed outside in mid March.

Peas are a cool season crop and dislike summer heat and humidity. They stop flowering and producing when the temps rise. For that reason, they tend to be planted quite early, often following the adage 'as soon as the soil is workable'. Obviously that is going to be a factor of location. In my area, the rule of thumb is President's Day or as soon as possible after.

I have done both direct sowing and starting indoors and IME, it is far easier (and generally much more successful) with direct sowing.

FWIW, I will be presoaking and planting my peas by the end of this month.

Peas can handle cold weather, snow, and frost decently, but if you have started some inside you just have to worry about stressing the pampered seedlings. So gradually expose them to direct sun for a few days, and avoid very cold nights. You want to get the peas in the ground and growing before hot weather.

Thank you so much everyone. I am in zone 7A and the average last frost date is given to be April 25th. I know you can plant out pea seedlings successfully, I have done it before. I just cannot not remember when I used to plant them outside. I did not give it much thought in those days. @robert567 thank you for reminding me to harden them! I think I will aim for mid March @vgkg Z-7 Va and as all of you say peas can handle a good deal of cold. I think the seeds need more warmth to germinate than the young plants need to stay alive or grow. So starting them inside maybe more work, specially if you have a lot, but you probably gain a lot of time for harvest.

Its just not going to work to sow directly in my garden and I am only going to plant one row, about 15 feet against a trellised fence, so it wont be much work.

I just tested how long the dry peas I have will take to germinate: after soaking them for four hours I put them in some seed starting mix and on a heat mat and many were germinating in 24 hours. So starting them inside about two weeks before planting will work out.

@kitasei2 like you I fully plan to only cut the pea plants from near the soil not pull them out when they are done. However, by the time the plants have flowered and fruited there is not much nitrogen resource left in the roots. Still there will be some and the valuable bugs will be there for the future so leaving the roots is a good thing.

A fifteen foot row of peas is a heck of a lot of plants in my book. To get a decent crop they need to be planted in a band about 6 inches wide with the peas 3 or 4 inches apart. So around 270 plants. What is the issue with sowing them direct?

We like lots of peas here for fresh eating and freezing by planting 2 long 25' rows on both sides of a 25' trellis basically making a 50' row. Our plants are much closer together at about 2 apart with the rows about 10" apart on either side. The trellis is oriented N-S so that both sides get full sun all day (~8 hours direct light - pic below).

The outer fencing is to deter deer which roam around the yard at night, these peas below were just starting to bloom (last Spring) and their final height is 2x as high before the plants putter out.... "Frosty" is the variety....

I go by the adage, "When forsythias bloom plant peas; when dandelions bloom, plant potatoes." Of course that means pea seeds not plants.

OK @floral_uk z.8/9 SW UK you asked and I am embarrassed to say it. The area I want to plant the peas is still full of weeds. The last two years I have been eradicating weeds by pulling out one perennial weed at a time over and over as they come up throughout the season. And then mulching heavily. I am not just trying to cover up the weeds but get them out from the roots. For a number of years I have not been able to garden at all and that has taken a toll on my yard. I have only finished, well almost finished, weeding certain sections of the garden and where I want to plant the peas is not one of them. The soil there is lovely though. It gets good water and the weeds and leaves have been composting in situ forever.

My rationale is I will hand till a small strip of land with compost, insert the pea plants and then mulch thickly with bark around the plants. Subsequently when the weeds come up they will be easy to distinguish from the larger pea plants and I can remove them (the weeds) as they appear. If the pea seeds had to compete and I have to weed as they germinate it just wont work.

On the other hand thank you for telling me I can plant the peas so close together and get that many plants in!!!! I was planning on putting in one or two plants every 6 to 8 inches and trying several different varieties.

@moosemac thats a great adage that I did not know. I dont see why you cannot plant pea plants at that time do you? Since peas can withstand a good deal of cold.