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Potting on Sweetpeas

#1 · 23rd December 2023, 8:45 am

Hi, I planted sweetpea seeds for the first time two weeks ago and they have really taken off. Didn't think they would shoot up so fast. They are very overcrowded - should I transplant them into pots to give them more space to grow before planting out in the spring?

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#2 · 24th December 2023, 11:07 am

Quote from Lee Garden Ninja on 24th December 2023, 11:07 am
Hi @mokwepa
Great question about when to prick out and pot on sweet peas.
It looks like your sweet pea seeds are really going for gold!
The key to success when growing sweet peas from seed is threefold:
Start off sweet pea seedlings the autumn before you want to plant them
Soak your seedlings overnight first
Plant them in individual pots or toilet rolls for their deep roots
I'd advise that you split these sweet peas ASAP into individual pots. My guide on pricking out and potting on seedlings or the video guide below should help.
https://youtu.be/seGiNYRhaZE
Sweet peas hate having their roots disturbed, and it will slow down their growth, so once you've pricked them out, don't panic if they don't put on any more growth for a month or so. It's better to do this now than in spring, so it doesn't stop them from actually flowering.
I'd pot your seedlings out into a good quality peat free compost. Then get them in the ground around March-April time next spring. Don't feed them through the winter the compost will have enough plant food for them. But give them a good compost mulch once you plant them out into the ground.
I thought it may help other Ninja gardeners by providing my brief guide on how to sow sweet peas below.
How to grow sweet peas from seed
Growing sweet peas from seed is a delightful and rewarding gardening endeavour. Here's a brief guide to help you successfully cultivate these fragrant and colourful flowers:
1. Selecting Seeds
- Choose sweet pea seeds from a reputable supplier or garden centre. There are various varieties available, each offering different colours and fragrances. Pick colours that work with your garden design or style.
2. Timing for Sweet Peas
- Start your sweet pea seeds indoors in late winter or early spring, about 4-6 weeks before the last frost date in your area. Sweet peas thrive in cool weather. Ideally, start them in Autumn and keep them in an unheated greenhouse or cold frame.
3. Preparation
- Soak the sweet pea seeds in water for about 12-24 hours before planting. This can help break their dormancy and promote quicker germination. You can also 'nick' them with a knife before soaking or put them in a plastic bag with a damp piece of kitchen paper in there for 2-3 days.
4. Container or Seed Tray
- Fill seed trays or small pots with high-quality peat free seed compost. Ensure the containers have drainage holes to prevent waterlogging.
5. Planting Seeds
- Plant the soaked seeds about 1 inch deep in the soil, placing them on their sides to prevent water from settling on the seed coat. Space the seeds a few inches apart.
https://youtu.be/DICGT44SMSs
6. Watering sweet peas
- Water the soil thoroughly after planting and maintain consistent moisture. Avoid waterlogging, as sweet peas prefer well-draining soil.
7. Temperature and Light for sweet peas
- Keep the containers cool with temperatures around 50-60°F (10-15°C). Once the seeds germinate, provide plenty of light to encourage healthy seedling growth. Turn and rotate trays if the seedlings lean so they grow up straight.
8. Transplanting Sweet Peas
- When the seedlings have grown to about 3 inches tall and have developed a couple of sets of leaves, transplant them into larger pots or directly into the garden. Sweet peas have delicate roots, so handle them carefully. They may struggle to flower if planted out too late and never move them once in the ground.
9. Support Structures
- Sweet peas are climbing plants that require support. Install trellises, stakes, or netting in the planting area to provide a structure for the vines to climb.
10. Planting Position
- If transplanting outdoors, choose a sunny location with well-draining soil. Plant the seedlings in a trench to encourage root development.
11. Watering and Mulching
- Water consistently, especially during dry periods. Mulch around the base of the plants to retain moisture and suppress weeds.
12. Deadheading sweet peas
- Regularly deadhead spent flowers to encourage continuous blooming. This also prevents the plant from setting seed, promoting more flower production.
13. Harvesting
- Once your sweet peas start flowering, enjoy harvesting them for bouquets. Regular harvesting can stimulate more blooms.
By following these steps, you'll be on your way to enjoying a colourful display of fragrant sweet pea flowers in your garden.
I hope that helps!
Lee Garden Ninja

Hi @mokwepa

Great question about when to prick out and pot on sweet peas.

It looks like your sweet pea seeds are really going for gold!

The key to success when growing sweet peas from seed is threefold:

Start off sweet pea seedlings the autumn before you want to plant them
Soak your seedlings overnight first
Plant them in individual pots or toilet rolls for their deep roots

I'd advise that you split these sweet peas ASAP into individual pots. My guide on pricking out and potting on seedlings or the video guide below should help.

Sweet peas hate having their roots disturbed, and it will slow down their growth, so once you've pricked them out, don't panic if they don't put on any more growth for a month or so. It's better to do this now than in spring, so it doesn't stop them from actually flowering.

I'd pot your seedlings out into a good quality peat free compost. Then get them in the ground around March-April time next spring. Don't feed them through the winter the compost will have enough plant food for them. But give them a good compost mulch once you plant them out into the ground.

I thought it may help other Ninja gardeners by providing my brief guide on how to sow sweet peas below.

How to grow sweet peas from seed

Growing sweet peas from seed is a delightful and rewarding gardening endeavour. Here's a brief guide to help you successfully cultivate these fragrant and colourful flowers:

1. Selecting Seeds
- Choose sweet pea seeds from a reputable supplier or garden centre. There are various varieties available, each offering different colours and fragrances. Pick colours that work with your garden design or style.

2. Timing for Sweet Peas
- Start your sweet pea seeds indoors in late winter or early spring, about 4-6 weeks before the last frost date in your area. Sweet peas thrive in cool weather. Ideally, start them in Autumn and keep them in an unheated greenhouse or cold frame.

3. Preparation
- Soak the sweet pea seeds in water for about 12-24 hours before planting. This can help break their dormancy and promote quicker germination. You can also 'nick' them with a knife before soaking or put them in a plastic bag with a damp piece of kitchen paper in there for 2-3 days.

4. Container or Seed Tray
- Fill seed trays or small pots with high-quality peat free seed compost. Ensure the containers have drainage holes to prevent waterlogging.

5. Planting Seeds
- Plant the soaked seeds about 1 inch deep in the soil, placing them on their sides to prevent water from settling on the seed coat. Space the seeds a few inches apart.

6. Watering sweet peas
- Water the soil thoroughly after planting and maintain consistent moisture. Avoid waterlogging, as sweet peas prefer well-draining soil.

7. Temperature and Light for sweet peas
- Keep the containers cool with temperatures around 50-60°F (10-15°C). Once the seeds germinate, provide plenty of light to encourage healthy seedling growth. Turn and rotate trays if the seedlings lean so they grow up straight.

8. Transplanting Sweet Peas
- When the seedlings have grown to about 3 inches tall and have developed a couple of sets of leaves, transplant them into larger pots or directly into the garden. Sweet peas have delicate roots, so handle them carefully. They may struggle to flower if planted out too late and never move them once in the ground.

9. Support Structures
- Sweet peas are climbing plants that require support. Install trellises, stakes, or netting in the planting area to provide a structure for the vines to climb.

10. Planting Position
- If transplanting outdoors, choose a sunny location with well-draining soil. Plant the seedlings in a trench to encourage root development.

11. Watering and Mulching
- Water consistently, especially during dry periods. Mulch around the base of the plants to retain moisture and suppress weeds.

12. Deadheading sweet peas
- Regularly deadhead spent flowers to encourage continuous blooming. This also prevents the plant from setting seed, promoting more flower production.

13. Harvesting
- Once your sweet peas start flowering, enjoy harvesting them for bouquets. Regular harvesting can stimulate more blooms.

By following these steps, you'll be on your way to enjoying a colourful display of fragrant sweet pea flowers in your garden.

I hope that helps!

Lee Garden Ninja