How to Grow Sweet Peas from Seed
The following two lists shows what tools and equipment I used to grow the Sweet Peas. Not all are strictly necessary but they are listed for completeness. For example - you would only need a heated mat if you had nowhere warm to germinate the seeds - or you can use re-cycled pots from last year if you have them.
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Things You Will Need to Grow Sweet Peas
- Sweet Pea Seeds
- Propagator Tray
- Single Pots or Starter Trays
- Kitchen Paper Towel
- Plastic Film
- Bamboo Canes
- Garden Twine
Tools You Will Need to Grow Sweet Peas
Step by Step Guide
If you want a quick overview then I suggest you first watch my Youtube Video How to Grow Sweet Peas from Seed . The following steps are also in the video but more detail is given in the sections below:
Step 1. Buy Some Seeds
Sweet Pea Seeds are available in Garden Stores or you can buy them on-line.
The variety that I am showing you how to grow here is called 'Royal Mixed'.
On the rear of the packet are usually shown growing times and instructions for your region.
Step 2: Soak Seeds Overnight
Sweet Pea Seeds have a hard brown protective case. In order to get water through this case and into the seed center to start germination it is recommended to soak the seeds overnight.
First get a small plastic tray (here I am using one that was a fruit packaging).
Fold up a Kitchen Paper Towel and place it in the base of the plastic tray.
Moisten the paper towel with water (enough to soak the paper but not so much that the seeds are submerged in water).
Then place the Sweet Pea Seeds on top of the wet paper.
Cover the tray with Plastic Film and leave overnight. The plastic film keeps the air in the tray humid which helps the seeds absorb water.
Step 2: Plant Seeds in Pots
Fill the pots with Compost then gently press it down to remove any air pockets.
Seeds need air, heat and water to germinate. It is best to moisten the compost before adding the seeds otherwise they can all be washed to the edges of the pot if you water afterwards.
Place one seed on the top of the compost in the center of each pot. Some people place 2 per pot in case one fails to germinate and then remove the weaker of the two.
Cover the seeds with 10mm (1/4 inch) of compost. Press the compost down gently to remove any air pockets. This allows the seeds to make contact with the moist compost and absorb water which they need to germinate.
Fit a label. This is important, especially so if you have several pots growing lots of plants. It can be several weeks until the seeds germinate and when they do it is not obvious what plants they are. So it is a good idea to identify them.
I use home made labels - sometimes from laminated paper and sometimes from wooden stirrers from coffee shops. You can also buy ready made Labels if you prefer.
Step 3: Keep Warm and Watered
Keep warm at approx. 15-20 degC (60 to 68 degF). I keep mine in a spare room but not in direct sunlight as this can fry the seedlings when they germinate. If you dont have a warm room you can buy a Heated Mat that goes under the tray.
Check the compost daily and if it starts to get dry use a Mist Sprayer to moisten it without disturbing the seeds.
Step 4: Seeds Germinate
Within 12 to 21 days the seeds will germinate and seedlings will appear.
Step 5: Pinch Out Tips
When the seedlings are between 4 and 8 inches high (100 to 200mm) pinch the growing tip out. This encourages the plant to grow side shoots - see next step.
Take the growing tip between your forefinger and thumbnail and snip the growing tip off using your nail as your blade.
By pinching out the tips side shoots will start to grow. Here you can see 3 shoots per plant eventually giving 3 times the amount of flowers!
Step 6: Plant Outside
When the danger of any frosts has passed it is time to plant outside. First dig your soil, removing any stones and weeds.
Here I am planting in a border next to my fence.
Next dig a shallow hole about 30cm (12 inch) square and approximately 150mm (6 inch deep).
Fill the hole with compost then cover with soil. The roots of the Sweet Peas are going to grow into the compost.
Sweet Peas like a lot of water and the compost is going to help retain the water in the soil as well as providing nutrients.
Take four Bamboo Canes and stick them in the ground - one in each corner of the hole you just dug.
Tie the tops of the Canes together using Garden Twine to form a wigwam shape.
Use a Garden Trowel to dig a small hole in the soil on the inside corner of each cane. Carefully remove the plant from it pot and place in the hole. Gently press the soil around the plant roots.
Repeat for the other 3 canes.
Finally give the plants a good soaking.
After this, keep the plants well watered (daily) and keep weed free.
Step 7: Tie with Twine
When the plants are approximately 30cm (12 inches) tall they will need supporting to stop them flopping to the ground. Use Garden Twine to to tie around the canes as shown. Make sure the plants are held on the inside of the twine.
As the plants grow taller you will need to keep repeating the tieing up process as they grow up the canes.
Step 8: First Flowers Appear
After about 4 to 6 weeks the first flowers will begin to appear.
Step 15: Keep Watered and Dead-Head
Keep watered and weed free. Dead head (remove any dead flowers) to prolong flowering. This stops the plant putting its energy into seed growth and into production of new flowers.