**Note- This post is geared towards the home gardener growing sweetpeas in a backyard type of setting.
Sweet peas- once you get a whiff, you’ll never be without them in your garden again. Sweet peas in the South aren’t super common. However with the rise of cut flower gardens over the past few years, they are getting more popular. But it’s not all sweet smelling purfume. Growing them in the South requires a few tricks that are different from the common sweet pea knowledge you’ll find on the interwebs.
Let’s start from the beginning: Seeding
Sweet pea seeds look like brown or occasionally white dried peas. They are in the legume family but all parts of the plant are poisonous. Smells only on these! ( They’ve always been fine to grow around my animals- I think you have to ingest quite a quantity to be dangerous but always a helpful thing to know about any plant. )
A lot of sweet pea seed is bred in England and New Zealand. You can import the seeds in small quantities fairly easily or you can buy it from some new breeders that are popping up in the US. Ardelia Farm in Vermont and Sweet Pea Gardens in California are two sources I’ve used with good success. Fresh high quality seed is the most important factor in getting good germination. You’ll see recommendations for soaking or nicking seeds but it’s not necessary. Store your seeds in the freezer once you received them until you are ready to plant.
There are early and late flowering sweet peas. Look for varieties that say they are a spencer type as these are the late types and are better for growing outside. The early types are bred for greenhouse growing and are not as cold tolerant. Some of my favorites are Nimbus, Oban Bay, Mollie Rilstone, Charlie’s Angel, and Strawberry Fields.
It’s best to start sweet pea seeds in containers and plant out a transplant versus direct sowing. Sweet pea seed is not cheap (around 50 cents a seed) and I’ve often seen seed rot or get eaten by rodents when direct seeded. You’ll want to wait until the temps are just right before sowing- daytime temps of average 60’s and nights at 45-55 degrees. So don’t fret if you haven’t started yet, you’ve got plenty of time.
Sow into containers around 2” deep and around 1” in diameter. You don’t need a super big or deep container. NOW—- any northern grower who just read that is saying- “You’re wrong!” Here's one of the instances that Southern growing is different: in the South, we get a small window where we get the correct temps to sow sweet peas. Sow too early and you get leggy plants due to the heat, too late and they don’t get established well before the cold. So the goal is to get the seed started in a controlled environment and have it ready to plant within 3 weeks from sowing. Northern growers will plant into deep pots with lots of room for the transplants to develop as they grow in a very cold environment and then get planted in early spring. I’ve used the sow it and transplant it quickly method for years and it works really well in the South. Fall planting seedlings in the South will give the same slow growth and root development in the ground that Northern growers get in a pot.
Growing out and Planting your seedlings:
Once your seeds have sprouted, keep them in a cool place with bright light. Usually our temps towards the end of October are perfect. I don’t recommend starting sweet peas inside under grow lights because most houses are too warm. Sweet peas like it cool! This is counterintuitive to how most seeds are started but if you keep them too hot, they get too tall too fast and they fall over and break.
Once the seedlings are 4ish inches tall, they should be ready for transplant. You want to make sure they have at least once set of true leaves on them.
Plant into a well composted bed, preferably with the soil raked up to raise it a bit for good drainage. You don’t want to rot them out. Sweet peas are hungry little plants so make sure your bed is well amended with a good organic fertilizer and lots of compost. Space them 6-9” apart. 9” is preferable if you have the room because it will make it easier to harvest come Spring.
Keep the plants watered until established. During the winter, water if the soil becomes dry. Over the winter the plants will begin to branch out from the center and each branch will be around 8-12” long laying on the ground. This is fine for now— Don’t put up your trellis until late February/early March. When you see the plants start to turn upwards and try to climb, then it’s trellis time.
During the winter when it warms a little, 60+ degree days, you can apply a water soluble fertilizer such as fish emulsion.
Sweet peas are very cold hardy. They can take temps down to low 20’s before they need cover. I cover mine once or twice a season and I’m usually playing it safe rather than sorry.
Trellising and Harvesting:
I use a netting called Hortanova Tenax netting. It comes in different widths and the 6’ wide is really good for sweet peas. The vines will grow pretty tall but I never put up a trellis taller than 8’ because I know I couldn’t reach any higher and I don’t want to get out a ladder. Once they start getting tall, you just have to cut harder to control the growth. Use a t-post about every 6’ if growing in a row. Stretch your netting very tight and secure it with zip ties to the t-posts. You can also make a tripod style trellis from bamboo canes or other tough supports. To encourage the sweet peas to grow upwards and not out, I take bailing twine and run it laterally about 3” off the ground and use it to scoop the sweet peas up. Then I add a row about every 6” for the first 2 feet, then 1’ apart after that. I usually stop around 4-5’ because if you add too much after that, it gets hard to harvest.
Sweet peas will begin to grow stems with buds in April usually. They will look droopy at first but will straighten out as they grow. The correct harvest stage is when 2/3 of the buds on a the stem are open. You can cut at the base of the flowering stem or you can cut down the vine if you need a longer stem. To ensure you are getting fresh stems, cut 2-3X per week. The more you cut, the more they flower.
There is a phenomenon called bud blast that can affect sweet peas in the spring. Sweet peas are very sensitive to climate/environmental changes. For example, if the temperatures swing dramatically or we get a ton of rain, it can cause the buds to turn brown and drop off. The buds will reform, usually takes about 2 weeks. I see this happen usually every year. It’s just a fact of growing sweet peas in a climate that fluctuates a lot during the Spring.
Aphids can also be common on sweet pea flowers and they can even show up before flowering begins. So keep an eye out for them. Shower them off with a spray of water or use a insecticidal soap.
Sweet peas have a vase life of about 5 days on average. If it’s a cool spring, then they may last longer in the vase. If it’s hot, then maybe only 3-4 days. Mine usually keep flowering until late May/early June. Keep watering them and harvesting to keep the blooms coming!
But most of all — Enjoy your Sweet Peas! I don’t know of a better flower that is such a treat for the senses- smell, touch, sight!
**Sweet pea transplants still available in the online store.