How to Start Sweet Peas from Seed

Sweet peas are beautiful and incredibly fragrant flowers that are pretty easy to grow from seed. They come in a wide variety of colors, which makes them even more fun! If you're interested in growing sweet peas, starting them from seed, this blog post is for you.

The first decision you have to make is what type of seeds are you going to grow. This is the fun part! There are several great seed places to source great seed stock. We love sourcing sweet pea seeds from Renee’s Garden, Botanical Interests and Farmer Bailey the most, but there are many other places you can find great seeds to start with. All of these can be ordered online, or found at your local garden center. The trouble with selecting seeds is narrowing down the list of which ones you love the most. If you’re like us, you’ll want to grow ALL the colors.

Once you have your seed varieties selected and seed packets in hand, it’s now time to think about starting them. If you read the seed packet, most say to start them 4-5 weeks before last frost, which is absolutely fine, but what we’ve found is that starting them that late doesn’t give us a ton of time to enjoy these blooms before our summer heat sets in and kills them off. With this in mind, we start our seeds in late January in order to have them planted outside by March 1st.

We’re located in zone 5b, Central Iowa for those of you wondering. It does get very cold during the winter months, but read on, we’ll address how to transition and plant them outside despite cold conditions, below, but first we need to talk about how to start these seeds to get them going.

Drain off all of the water from your seeds, using a strainer. and transition your seeds into a peat pot, recycled yogurt containers, old milk jugs, or a seed starting tray, filled with seed starting medium, which you can find at your local garden center. We like to use a 72 cell tray to start our seeds, because we generally start about this number of sweet peas each season.

Before placing seeds in the growing medium, make sure the medium is moist, but not soaking wet. Place your seeds on top of the seed starting medium and after all are set in place, push each of them 1/2” into the seed starting medium and cover. From here, place them in an area that has light exposure, but not direct sunlight. We like to pick a cooler, spot for them to germinate with temps around 60 degrees F. If kept at this consistent temperature, plants should emerge in 7-12 days.

We’re often questioned about why ‘pinching’ is necessary for sweet peas. It’s really important, because it helps your seedlings become stronger plants and it also helps promote branching (new growth) on the plant, which makes them even stronger before they go into the ground. They need to be pretty tough and well established before they can be transitioned out and planted in the ground.

It’s almost time to plant your seedlings outside! We plant ours outside on March 1st, which we addressed above, now we’ll get to how we do this. Before we get to planting them, we’ll talk about the ‘hardening off’ process.

Hardening off is the process of transitioning your plants outside to prepare them to be planted. This process is necessary to toughen your seedlings to the elements of growing outside, such as directl sunlight and wind. After seedlings have been growing inside, in a controlled environment, they’re a little fragile. In order to transition them out to harden them off, bring them outside for an hour the first day to start, keeping them in a protected area out of direct sun and high winds.

From this point going forward, you’ll bring them outside each subsequent day for a longer period of time until you run you hand over the top of the plants and feel that they are stiff and strong, which is where the name hardening off comes from. Once you’re achieved this, your little seedlings are ready to be planted outside!

Your sweet peas are ready to plant, so not it’s time to prepare your planting area. Sweet peas prefer well-draining soil with plenty of organic matter. Choose a spot in your garden that gets plenty of sunlight, but with ample afternoon shade to keep them from overheating and prepare the soil by adding compost or other organic matter.

After your growing area has been prepared, add a small garden trellis in the middle of your planting area and plant your seedlings on either side, about six inches apart. Keep in mind that once your sweet pea plants have reached 12” of growth, begin to train them to grow up the trellis, by adding twine and plant stakes, gently weaving the vines around the twine.

Since we plant our sweet peas in the ground on March 1st, we give them a little frost cover protection with agribon to cover them during temps well before freezing, uncovering them during the day and for times when the temperature is at/above 32 degrees F.

Sweet peas need regular watering and fertilization to grow strong and healthy. Water them regularly, but be careful not to overwater as this can cause the seeds to rot. Fertilize your sweet peas with a balanced fertilizer once a month.

If you need this information in a bit different format, check out our YouTube video on How to Start Sweet Peas from Seed. Additionally, in the video description box, you can find links to all of the tools we use to grow sweet peas.

Sweet peas typically bloom in the spring and early summer. For us, they boom May through the end of June. We hope y’all enjoy the beautiful colors and fragrances of your sweet pea blooms and find a place to squeeze them into your garden year after year!

XX Jenn and Adam