How To Grow Sweet Peas from Seed

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I have been growing sweet peas for three years now- but you wouldn’t know it because I have failed miserably for most of those years…

Last year I was really determined to grow sweet peas successfully and I took a bit of time to learn what I was doing wrong. The third time must really be the charm because last spring we experienced much better results than we had with all of our other, previous attempts.

So if you want to give sweet peas a try yourself, stick around because I want you to learn from my mistakes. In this blog post, I’m sharing everything I did wrong, as well as what I did right so that you too can enjoy your best crop of sweet peas ever!

If you’ve never grown sweet peas before then you may not even realize what you’re missing out on.

For me, I was first drawn to sweet peas because I loved how beautifully they trellised. And I really thought that sweet peas, with their ability to climb, would add a bit of whimsy to my cutting garden.

However, after growing sweet peas (with mild success), what I really fell in love with was their irresistible, sweet scent.

And it was that intoxicating smell that gave me the motivation to keep trying my hand at growing sweet peas until I finally found success.

Now that I have a better understanding of how-to grow sweet peas, I can look back at my failed attempts and see so clearly what I was doing wrong.

Believe it or not, sweet peas are not difficult to grow from seed; they just tend to follow a different schedule than the more traditional cut flowers that most of us are accustomed to growing.

Allow me to explain…

You see, the biggest mistake I made when growing sweet peas was growing them too warm.

For a lot of new growers especially, it can be difficult for us to grasp that some flowers have a preference for cold.

Sweet peas are one of those crops that don’t just tolerate cold, they actually thrive in it. And while sweet peas may look delicate, they are anything but.

With my first few tries at sweet peas, I thought I was being kind to my plants by protecting them from the bitter cold. I repeatedly started my seeds in trays that I then placed on my heat mat, and I often waited until the threat of frost had passed before transplanting them out in my garden.

All of this was a recipe for disaster and it’s no wonder why my sweet pea plants struggled as much as they did.

Here’s what you really need to do in order to grow beautiful sweet peas…

When to Sow Sweet Pea Seeds:

If you live in a mild climate, you may be able to fall-plant and overwinter your sweet pea crop.

In Zone 5b where I grow, it’s simply too cold for sweet peas to survive our entire winter season- so I start my seeds in the very early spring.

Keep in mind that sweet peas grow best with the following temperatures:

  • 50-55 degrees Fahrenheit for germination
  • 35-50 degrees Fahrenheit to put on growth (Don’t fret about drops in temperature- sweet peas can handle dips into the 20’s just fine!)
  • 45-68 degrees Fahrenheit for flowering.

What this means is that for most cold-climate growers, you’re going to want to sow your seeds in containers in late January thru early March and transplant those seedlings out in your garden as soon as the soil can be worked.

I often like to take my cues from Mother Nature and as soon as I see the daffodils start to peak above the soil- that’s when I know it’s time to plant my sweet peas outside.

Just to give you an idea of the timeline I use; last year I sowed my sweet pea seeds in trays indoors on February 13th and I planted them outside on April 10.

Best Containers for Growing Your Sweet Peas:

Another mistake I made early on with sweet peas was not giving them enough room to grow. Sweet peas produce long tap roots + those roots want to stretch deep!

Too small of seed starting trays can restrict the growth of your plant’s roots; and so, I’ve learned to use a larger tray to sow my sweet pea seeds into.

At minimum I will use a standard 50-cell seed starting tray. I’ve recently transitioned to using these deep root trays, which give my seedlings even more room to grow, and I feel like my plants really benefit from the extra room.

Now, other than paying attention to which seed-starting tray I’m going to use, I really don’t over-complicate the rest.

I simply use a well-draining seed starting mix (and potting medium will do!) to fill my tray; and I sow one seed about a half inch to an inch deep per cell.

I do not soak my seeds prior to planting like some sources suggest and honestly, I’ve never had a problem with germination.

Once planted, I double-check that my tray is moist and I place it into my minimally heated grow space. Remember, sweet peas germinate best in temperatures between 50 and 55 degrees Fahrenheit.

In 7 to 10 days, once I see that the majority of my tray has sprouted, I move it to a cooler location where my seeds will continue to grow until it’s time to transplant outside.

At this stage, your seedlings will put on some top growth- but more importantly, they’re growing a robust root system below the surface of the soil.

I will supplement with light as my plants put on growth since I’m not growing in a greenhouse. But remember, when growing in a cool environment, you want your plants to stay short.

I often place my LED lights just a couple of inches above my plant-starts because I don’t want them to stretch towards the light. Short, robust plants are what we’re really after!

Transplant Your Sweet Pea Seedlings Outdoors:

As I’ve shared earlier, I transplant my seedlings out in the garden once my night time temperatures are consistently above 20 degrees Fahrenheit.

Make sure that you’ve properly hardened-off your plants prior to planting outside. Then plant your sweet peas into an area with well-draining, fertile soil. I space my sweet peas 4-6 inches apart. I prefer tight-spacing as it creates a more wild effect as the sweet peas start to vine.

Don’t forget to give your seedlings a well-anchored support to climb on.

In years past, I’ve relied on Hortonova netting to be a trellis for my sweet peas. Last year, I wanted to feature my sweet peas in a more decorative way- and so, I fashioned cattle panel that I bought from my local farm store into a small arch.

I’ll admit, I really enjoyed being able to surround myself in sweet peas as I walked through my short tunnel. I’d highly recommend this project if you want to create this sort of magical space for yourself in your own garden- it’s worth the extra effort!

Caring For Your Sweet Peas:

As spring gets underway you’ll notice your sweet peas almost jump above the ground!

Ideally, you want your plants to put on as much growth as possible before the temperatures get too warm. Remember, sweet peas are a cool-season flower + temperatures above 80 degrees will shut your plants right down.

But during those cool spring days, you can expect your sweet pea plants to bud up + reward you with a bounty of beautiful blooms.

To keep your plants producing as long as possible, be sure to keep on top of your harvest. Don’t be afraid to deadhead spent blooms as it will keep your plants from going to seed.


And now all that’s left for you to do is enjoy your hard work! Savor that delicately sweet scent that comes from sweet peas growing in your garden. I can guarantee that once you experience these blooms for yourself, you’ll never want to go a spring without them!

Have you ever grown sweet peas yourself? I’d love for you to share some of your best growing tips in the comments below!

Picture of Britney Zondlak

11 replies to “How To Grow Sweet Peas from Seed

  1. Thank you so much for all this wonderful information! I too, live in a zone 5b. I’ve never grown sweet peas before so this post was perfect! I bought seeds from Floret last fall and can’t wait to see them bloom. I love your cattle fence idea! I have one section of a 4×4 raised bed section so that’s what I’m going to do with it!

  2. I live in the same zone and was wondering if I can direct sow sweet pea seeds in a raised garden bed in mid April? I just don’t want to bother w starting seeds! I mean without a greenhouse where do I grow seeds indoors in that cool of a temperature? Thank you.

    • You certainly can direct sow sweet peas! I don’t blame you for not wanting to fuss with the seed starting stuff 😉 Sometimes it’s just too much of a hassle. Best of luck!

  3. I have my sweet peas up and growing!! I’m hoping for beautiful blooms!! Just wondering when they started blooming for you and about when they were done. I’m guessing the timeframe is similar to sugar snap, snow peas, etc. I’m in the same zone as you in southeastern Wisconsin.

    • So exciting! I hope you experience beautiful blooms as well 🙂 Sweet pea season is unfortunately short + sweet for us here in Michigan. Ours usually start blooming Mid to Late May and will continue for a few weeks into June so long as the temperatures don’t get too warm on us too quickly (remember, sweet peas don’t tolerate consistent temperatures above 80 degrees well). You may be able to pro-long the season of your sweet peas by keeping up with the harvest (it’s important to deadhead spent flowers) and providing some afternoon shade. Best of luck!

  4. Do you have a favorite variety of sweet pea for cut flower bouquets?

    • I’m not sure I could pick a favorite- they’re all so fun + unique! I do prefer to grow Sweet Peas that are part of the “Spencer Series” as those varieties tend to have longer stems, and bigger blooms that are more ideal for bouquets!

  5. I live in zone 5b as well. I have started sweet peas in deep root pots in an unheated part of my basement. They have sprouted! Where can I find a cold place in my house to grow them? I have tomatoes started under LED lights but it’s too warm for them there. It’s too rainy to plant them outdoors just now.

    • Perhaps a garage space would be sufficient until the pain passes? Sweet peas “bulk up” and grow best when temperatures are between 35 and 55 degrees 🙂

  6. Hello, all!
    I live in Zone 3, Edmonton, Alberta, Canada. I have grown sweet peas all my life without a problem, as did my parents. They planted seeds (sprouted) in the last week of April. I buy sweet peas from the greenhouse in mid-May and plant directly in the ground. I have two beds of sweet peas: one is a south-facing bed, and the other faces east against a fence. My plants grow 7-8 feet tall, and last until the first frost in late September. I cut flowers throughout the summer, and their scent fills the house. Due to a concussion in 2021, I lost my ability to smell them, but I will never forget their scent! It is one flower I will always plant.

    • Love hearing about your experience growing sweet peas! Especially love how much meaning they hold for you- it’s quite special indeed.

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Hey there, I'm Britney!

A dairy farmer turned flower farmer growing + selling specialty cut flowers in West Michigan! I think flowers are the best way to savor the magic that comes with every season- that’s why at Two Sisters Flower Farm we grow everything from daffodils in the spring to pumpkins + dahlias in the fall!

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