Sweet Peas, Lathyrus odoratus, love a rich soil with lots of compost, lots of fertility, and aren't too fussy about soil, as long as it isn't too sandy or doesn't have too much clay.
Amend your soil where the vines will grow, and string up some sturdy hemp string, or attach a trellis to a board fence or on a wall, for the flowering vines. They can scamper up the branches of a shrub that leafs out late in Spring. I've had fun planting them in a sunny position at the foot of a large old lilac and they bloomed before the lilac blooms and the sweet peas were nearly done by the time the lilac leaves appeared.
There is also a bush Sweet Pea, and I've had good luck with that version also. So if you don't have room for a trellis or have a wire fence, just plant the shorter ones and you can still enjoy the delicious fragrance.
John Keats loved them so much he took a fountain pen to paper and wrote....
Here are sweet peas, on tiptoe for a flight**********
With wings of gentle flush o’er delicate white
And taper fingers clutching at all things,
To bind them all about with tiny rings.
Soak the seeds overnight before you plant them and they'll sprout in about a week or so. After 9 days of waiting, here are my sprouts at 1 day old, 3 days old, 5 days old, and 7 days old!
You can see the little tendrils already, so these need some skinny little branches and twigs to help them get over to the trellis on my patio. It is gonna be fun watching them climb up!
Protect them from slugs, snails and birds and goats and chickens if you got 'em!
Keep them watered well, but don't drown them and if you get some sun on them, they will really take off growing rapidly and probably start blooming in April.
This is California gardening... for a colder climate like Washington, check this post I did in 2012.
Here's a few of the colors you can expect: All the lovely pastels, and dusky tones, almost black, and some are bi-colored, but they are working on the ever-elusive yellow. Blue is particularly charming in the Sweet Pea!
The fragrance is a bit of sweet Spring charm, the flowers are gorgeous and complicated, and arrive on long slim stems. A bunch of them in a vase or Mason Jar, is a simple pleasure.
Always choose varieties that say on the package or catalog description, that they are fragrant. Sadly, in the quest for color variety or heat tolerance, a lot of fragrance power has been lost.
I always choose the old-fashioned, or heirloom seeds, but this year, I'm trying a New Zealand line, Cheri Amour, from Renee's Garden. This variety promises to be both fragrant and beautifully colored with solids and bi-colors, and the petals are ruffled!
Don't eat these peas.... they are not the garden peas... Sweet Peas are mildly poisonous.
A few old fashioned Sweet Pea varieties are Old Spice which resists heat, Flora Norton, Miss Willmott, the Incense blend, and the Spencers, and here's a link to Swallowtail Garden with 33 delightful varieties. There is still time if you hurry!
Renee's Garden seeds are here.
Beloved for centuries, this farm in Southern California celebrates an April Sweet Pea day!