Instructions for Growing Sweet Peas

Soaking (or not)

Trials have shown that soaking sweet pea seeds detrimentally affects germination rates of healthy seeds. We do not recommend soaking.

Timing

In areas where the ground does not freeze nor flood, you can sow in Autumn and overwinter seedlings in their beds. If your ground freezes, or you have standing water in your garden for the winter months sow 6-8 weeks before your ground is workable.

Starting Seeds

Using a mixture of soil and good compost in a deep cell, plant the sweet pea seed roughly 1/2” below the soil surface and cover, making sure the seed has good contact with the soil. Keep in a place that is consistently around 55F, and bottom water as needed. The soil should remain moist but not wet.

Temperature

Sweet peas want to be grown cold for the early part of their development. They germinate around 55F and do not require light. They also do not require dark. At this temperature, they should take 2 - 3 weeks to start germination. Resist the urge to start them warmer in order to force faster germination. Once they germinate, sweet peas do their best bulking up between 35F - 50F over a number of weeks. Cold grown sweet peas are stockier, healthier plants, with deep roots and vines that branch on their own, requiring no pinching.

Planting Out

Sweet peas can handle cold down to 25F, so once you’re past that danger, and have well-developed roots, it’s time to put them in the ground.   Gently remove them from their pot or cell tray and fill in the soil around them pressing down to pack the soil in around the newly planted roots. Water the roots in to eliminate any air pockets that may slow transplant.  They will spend a couple of weeks getting established and when temperatures warm to 70F, you’ll see them start to climb more quickly.  Unless your soil is very depleted, it is unnecessary to dig a trench and put down compost underneath the soil bed.  Standard amendments to bring your soil into balance are sufficient.  A soil test can be found here.

Trellising

Sweet peas are vines so they’ll climb what they can. A bamboo tripod, or a lattice fence, or a piece of cattle panel, or netting strung between two posts all work well. Do this within a few weeks of transplant when you see the plant beginning to put on growth.

Water & Fertilizer

Sweet peas will take a few weeks to re-establish in their garden bed and while they do, it can be helpful to give them a bit of fertilizer. Before flowers appear, a foliar spray of fish or kelp fertilizer once every other week or so will help (although it’s not necessary if they have good soil.) Once flowers appear, if you would like to continue to fertilize, choose one with the highest potassium in the NPK ratio on the container. Sweet peas require a lot of water and should be watered deeply 2 or 3 times a week, depending on the weather.

Pest Management

Like all creatures, plants have an immune system. A healthy plant will be able to defend itself against pests by not attracting them at all. So setting them up well at the beginning can do an amazing job at prevention. But pests happen. The best way to manage aphids or other sweet pea loving bugs is to attract their predators. Ladybugs (and more) love aphids. Some growers will purchase beneficial insects to help mitigate pests. A strong stream of water is a deterrent as well, but I will always discourage the use of insecticides. The balance of a garden relies on so many insects that will also be damaged and I never think it’s worth it to eliminate an important part of an ecosystem.

Harvest

Harvest the flowers when 2/3 of the blooms on the stem are open. If you can, harvest first thing in the morning as they’re most naturally hydrated after a night of recovery. Place them in clean, cool water, and enjoy for 3 - 5 days, keeping them out of direct sunlight and away from fruit to extend vase life. At the end of the season, let a few seed pods develop and when they’re brown and nearly cracking open, collect and label your seeds for future use. Sweet peas will grow true to variety and rarely naturally cross pollinate, so if you have a vine producing a spectacular bloom, that’s the seed to save.

Additional Resources

Bailey Hale, founder of Ardelia Farm, published detailed growing information a number of years ago that is a distillation of all of the best practices from well respected breeders and growers all over the world. They are a wonderful resource and I recommend taking a moment to read through them. You can find them by clicking here.