How to grow Sweet Peas in your garden. Their sweet perfume is a delight that cannot be surpassed. I grow them all through the Summer but I get started early in Spring from seeds.
How to plant Sweet Peas in your garden one easy step at a time. Growing these fragrant flowers is easier than you think. And if you choose the right ones and use a few tricks, you can grow them on through the summer.
Note: These are the annual type and not the perennial. Perennial Sweet Peas are not fragrant and can become horribly invasive in some areas.
I started my love affair with Sweet Peas back in 1988 when I lived in the San Joaquin Valley of California which has completely different growing conditions than here in my mountain garden.
Why am I telling you this?
Because it shows how Sweet Peas can be grown in completely different conditions and still be gorgeous.
We live in USDA Zone 8 with snowy winters and dry Summers.
In Zones 7 and above where winters are milder than in other areas of the country you may be able to sow Sweet Pea seeds in the Fall, around October but in other zones it is best to wait until late winter/ early Spring about 6 weeks before your last frost date.
I currently live in zone 8 and I have had Sweet Peas reseed themselves in Fall and sprout and still winter over to bloom in Spring but I have also endured late hard freezes that killed all my Sweet Peas in one fell swoop.
To be on the safe side start half of your Sweet Peas seeds early in February or March and save some to start later on, just in case.
How to Plant Sweet Peas Early
Sweet Pea seeds look like hard little peas but turn into the sweetest scented blooms you have ever smelled.
Some will tell you to nick or soak your sweet pea seeds overnight before sowing and after 20+ years of growing them, I can tell you to skip this step. It has not helped at all and if you still decide to soak, do NOT leave them in the water longer than 8 hours. They will rot very quickly.
Here is an example of how easy they can germinate, I found this little pea shoot starting from a seed I dropped accidentally in a pot next to a Sempervivum.
It sprouted while sitting on top of the soil, there was enough moisture without soaking. I used an arrow to show you, it kind of blends in.
Somewhere along the line this past Fall I dropped a seed and it sprouted where it landed. We have had a brief warm spell this month and I suppose it thought it was a good time to sprout!
When to Start your Sweet Pea Seeds
February is a good time for me to get Sweet Peas started in my greenhouse, in many other places March is an excellent time to start.
(Please Note: once it warms up outside I sow them directly in the ground) They prefer soil temps of 50 to 60 degrees so you may need to shade the area if it has already warmed up.
Check your last frost dates. Since sweet peas can germinate quickly and grow you don’t want to start too early as they do better if planted out in the garden when they are shorter and before the roots get too far.
If you live in warmer zones you can start yours in Fall. Wherever you live, start your sweet peas when it is cooler.
Starting Sweet Pea indoors
I use regular potting soil or compost and 3 or 4 inch pots. (taller pots work better as the roots get long but I have used these smaller pots with success)
Fill your pots with soil, not to the brim, you want some room to water. Poke the seeds in about half an inch.
I put in 2 seeds per pot but some like to space their sweet peas further apart in the garden so you can plant just one seed per pot.
Don’t press the soil hard, just firm them in. Water the seeds in and that will help tamp the soil down.
If you live in a very cold area and are starting early, place the pots in a warm spot indoors, but not on a heat mat. Sweet peas like soil temps on the cooler side.
When seedlings are about 4 to 6 inches tall pinch out the central stem just above a leaf joint, leaving about 2 or 3 leaf nodes, this will promote branching.
These below need pinching back.
You can snip them back to with pruners or just use your fingernail.
You can actually root the cuttings for more Sweet Peas, it is similar to rooting other plants from cuttings.
A great selection for heat tolerance is the Old Spice Blend.
I grew some of these by my greenhouse in a barrel alongside a rose and they did just fine even though it gets quite hot in this spot. Here you can see they have reseeded themselves.
They are a little beat up as the snow has been covering them for weeks and more snow is on its way but once warm weather is here for good they will get strong and crawl up the trellis.
I stopped cutting my Sweet Peas in September so they could go to seed and replant themselves and I collect some to pot up in the greenhouse.
A great variety just for cutting is Fairy Tale Blend. They have long stems great for floral arrangements but you should pick from all of your Sweet Peas.
Keep Them Growing All Summer Long
Cutting the Sweet Peas frequently, every 9-10 days will get continuous bloom all Summer long. If you don’t cut they will go to seed and that is it for the plant, no more blooms. This is especially important when it gets hot and dry.
I keep a soaker hose at the feet of my sweet peas for consistent watering, we don’t get summer rains.
Adequate water is one key to success when you grow Sweet Peas. A good mulch around the base of the sweet peas helps to keep moisture in the soil be more consistent.
Grow Sweet Peas in full sun with some afternoon shade, if you can. Where it is very hot, afternoon shade will help them survive the hotter months. They may take a brief rest from blooming but don’t despair, once the heat subsides a bit they will start to bloom better than ever.
Plant where the soil is rich and has good drainage or amend to make it so. They don’t like soggy feet.
Related: Build your Soil for the Best Flowers
Be sure to provide support, these can climb well above 6 feet and will wrap themselves around whatever they need to go up!
I planted some seeds in one of my pots of Bamboo, they will be happy as clams clamoring up the canes and I will enjoy their lovely perfume on my back deck all summer.
Sweet Peas are susceptible to powdery mildew. This doesn’t really do much harm to mine and I just keep picking the flowers, and many times the mildew disappears.
Good air circulation is key to keeping the mildew at bay and a healthy well-fed plant helps it to fight through it.
As I stated before we have dry summers, very little humidity, you may find you have to battle mildew more if you grow sweet peas in a humid environment.
Feed, feed, feed
Sweet Peas are heavy feeders so be sure to fertilize. A good soil drenching with a diluted organic liquid fertilizer every week should be good. A blend of fish emulsion and liquid kelp is highly recommended but I have used worm casting tea as well with success.
My favorite feed as of this moment is Agrothrive, it not only feeds the plants but it feeds the soil! Press the link to get 5% off your purchase. I am loving this stuff.
Aphids love Sweet Peas too but since I garden organically I have a large amount of Lady Beetles that live here so they take care of them for me. If they get out of hand I do spray the Aphids off with my water hose.
Plant your seedlings out in the garden around the time of your last frost. Set them about 4 to 8 inches apart and close to a trellis or support. You may have to tie them up depending on the type of support. I grow sweet peas by a cattle panel trellis and I just wind them up it as they grow. If I get more than one coming up in my pots I just plant them all together.
Have you tried Sweet Peas in your garden?
I wish you Happy Gardening!