I've never grown them before so I don't know when "too-late" is. I wintersowed some in February and direct sowed some end of March when I did my edible peas...the edibles are up and going but nothing yet from the Sweet Peas in either method :(

Vera

How warm is it? They need warmth for germination about 60-70 F; but cool to grow in. Some people start theirs in pots in the house, and then transplant in the garden bed. If your weather is still cool, go ahead and do that. It might be a tad late, try some and see what happens in your area. Later on in the year, you can plant in autumn (if you can) and see results a bit earlier. If you start them indoors, put them out to harden off for a few days before putting them in the garden. As soon as you see green, put them outside for a week. Never let them dry out at this stage; but keep them moist and not sodden. Have your supports up at the same time.

I never grew them before, but last year in late May or early June, I put some in front of the brick stoops that stick out from my front porch. Just dug a little and stuck them fairly deep, can't remember, no more than one inch, in the ground, watered frequently. The ones I had on a little ladder with chicken wire covering it did better than the ones I put in some bamboo stakes inside a wine rack. I will try something else with that but don't know what.

They seem to be stubborn about grabbing ahold of where you want them to and like to grab each other. Mine were pretty healthy, not as profusely blooming as I would have liked, tolerated the hot spot, and wanted to go much higher than I had prepared for them. They did bloom once they got started until the first frost. The ones by the wine rack fried in the hot sun more than the others, but maybe those got a little more afternoon shade from the neighbor's tree or the soil was better on that side or the heat absorbed by the bricks was too hot for them. I think they like a wire fence better.

Sweetpeas are called annuals yet a neighbor's mother planted some years ago on a fence, & they come up each year.The neighbor does nothing but mow along side them. I'm sure they'd give me a start as they've recently moved. Now, my questions (no green thumb)....how & when do I get the start and can I put up a trellis so it's not on my fence? Or should I put it on the chainlink but down from the honeysuckle? I don't want to tear up my fence w/wt from the flowers. Thanks! for any help.

They could be the annual kind reseeding themselves.
Or there are perennial varieties.
Not sure where you reside, which would have some bearing on sowing times. Regardless of whether these are the annual or perennial variety of sweet pea, if your neighbor's plants produce seed pods later this summer, you could snag some seeds that way cheaply.
Sweet peas would not impact a fence with their weight. They have delicate little tendrils that wrap around narrow gauge wire or plastic or branches of neighboring plants that allow them to grow upwards. They would grow fine on chain link.

My sweet peas tend to grow in so thick that I sometimes can't see the flowers for the greenery. Should I prune my sweet peas? What can I do to make the flowers show up more?

Thanks, deep roots. I'm in NE Oklahoma. I don't know enough about sweet peas to realize some self-seed. The neighbors have purchased another house & will be putting this one on the market.Think I'd better see about a start of them before they do that! All I can do is try...I think sweet peas are so pretty & smell good. Just didn't inherit a green thumb from either g'mother :-) thanks, again, for the information. It's greatly appreciated!!

Don't know if this is absolutely true but: if they're scented they are the annual kind. Perennial variety, while pretty, have no scent.

I grow sweet peas every year, they are Aprils birth flower, me, I'm an April fools baby. Love the look, the smell, the care free way they grow. I have grown them several different ways. Last year, and my favorite so far, I grew them in a whiskey barrel that sits on an antique hand dolly. I didn't provide support for them as I wanted them to grow up the dolly, they did somewhat, but they did spill over the edge of the barrel and it was quite impressive. I started some of the seeds in doors on April 1st (according to the farmers almanac, that is when you are supposed to sow them but that may mean outside) here in Montana it is way to cold in April to sow outside. When I planted my seedlings I sowed 4 more packages of seeds so they would be very full. The direct sown seeds soon caught up to the indoor grown ones and boy were they full!

This year I did the same excpet I put a tomato cage in the center of the barrel and the little guys are finding their way to it just fine. I also planted some in the ground by a fence and they don't seem to be doing as good. I think the bunnies are getting to them tho.

With that said, it isn't too late to direct sow them, they do need warmth to germinate, so they should go quite rapidly.