How to Grow Sweet Peas From Seed
Growing Sweet Peas is relatively easy and will reward you with bouquet after bouquet of blooms to fill your house or give you a lovely 'wall' of color and scent if you grow them for garden decoration.
Knowing when to plant sweet peas is important for success. Sweet peas will bloom profusely with wonderful flowers when started so that they have a long growing time in cooler weather as this helps to build a strong root system. A general rule is to plant sweet peas 6-8 weeks BEFORE your last frost date (you can find when your last frost date is here). However, in Zones 7-8 and above, you should start your sweet pea seeds in the autumn (find out your growing zone here).
Find out when to start sweet peas in your area by signing up to receive my sweet pea Seed Starting Planner.
My advice is to try growing sweet peas this year, and then grow them again next year (and all the years after – they are addictive!) and you will find a way to grow them that suits you and the area you live in.
Basic Growing Directions
- Fill your pots with potting soil and moisten thoroughly. I find it easier to pre-moisten potting mix by placing it in a bucket, adding water and mixing with a stick and then placing it into pots. Add enough water to make the potting soil feel like a wrung out sponge.
- Press the potting mix lightly into the pots.
- Use a pencil to create 2 holes in the potting mix and place 1 seed in each hole. The seed needs to be covered by no more that 1/4” - 1/2", so don't poke the holes too deep.
- Place a plant marker in your pot with the name of the sweet pea variety.
- Place your pots on a bright (but not hot) windowsill and let the seeds germinate. You should see shoots within 2 weeks or less. There is no need to water again until you see signs of germination.
- Once you see the first green shoot, move your pots to a bright location (an unheated greenhouse or cold frame would work depending on your location and temperatures).
- When your sweet pea plant has reached about 4-6 inches in height, it's time to plant it outside.
- Plant your sweet peas where they will receive full sun, be protected from strong winds and in free-draining soil.
- Dig a hole for your sweet pea and add the well rotted manure - mix it in with your soil. Remove the sweet pea from the pot and plant in the ground at the base of your trellis or other support.
- Water it in using the rose on your watering can or light spray from a hose.
- Protect from slugs, snails and birds.
- As the plant grows you will need to 'tie it in'. Simply use twine or some other garden string to secure the vine to your trellis.
- Cut flowers regularly as they fade to keep the blooms coming.
Choose Your Pot
The deeper the pot, the longer you can wait before planting out your sweet peas. The middle pot is a 4" pot - usually available from a good garden store.
To Soak or Not to Soak?
Some sweet pea experts advise soaking the seeds before planting. Other experts say that this is not necessary or can lower the germination rate. I conducted a small test to see whether or not I should soak my sweet pea seeds.