Jan 18, 20224 min read

Growing sweet peas

Updated: Nov 9, 2022

pink sweet pea flowers — Pink sweet peas

A mug with a picture of sweet peas and some sweet pea flowers — Sweet pea mug with sweet peas

Sweet peas have become a mainstay of the English garden - their frilly, colourful, scented flowers and fine, delicate twisting tendrils are an absolute delight for us gardeners and flower-lovers in the summertime.

January is a time for looking forward and planning and this is no less true when it comes to the garden - start sowing now for a beautiful crop of sweet peas this summer.

I have been sowing my sweet peas in the last couple of days, and have been reading up and listening to podcasts and instagram posts for some tips. So read on to see how I sow...

First things first - make yourself a really good mug of tea and then...

🌱 gather your quality sweet pea seeds

🌱 peat-free multi-purpose potting compost

🌱 a container - you can use 9cm pots, loo roll or root trainers...

🌱 space to store your seeds and seedlings both inside and outdoors.

a blue mug with sweet pea design filled with tea in the garden on a table with some flower seeds and plant pots — Tea in the garden - sweet pea mug

Sweet pea seeds

Of course there are big companies selling sweet pea seeds, like Unwins, Marshalls and Suttons, but there are also some lovely smaller companies who specialise in sweet peas, who are passionate about their products and take lots of care and attention over what they sell. I like to support small companies so I bought my seeds this year from Liz Stevens Gardens . I'll be trying 'Charlie Bear', 'Pink Perfection' and 'William and Catherine', as well as an old packet of old fashioned scented sweet peas from Suttons that I found in my seed box.

Soil

The soil should be quite fine for seeds, peat free, and free draining. If the soil is too free draining your seeds may not get enough moisture and you'll be having to water more frequently, if not free draining enough the seeds will be too wet. Add some perlite or horticultural sand to aid drainage if needed.

Pots

Sweet pea seedlings will need to put on really good root growth. If the pot isn't deep enough the roots will be too short and the plant won't be so strong. Choose a 9cm pot, or you can buy root trainers which are narrow and deep. Root trainers (above, left) have the added benefit that there is a large hole in the base of the pot - when the root reaches the bottom and there's no more soil it will start to develop more side roots on the main root in the pot, strengthening the plant.

You can also use toilet rolls (pictured above, middle) which are around 9cm deep and have some benefits - once the seedling has grown and you're ready to plant out, you can simply plant the whole toilet roll in the soil and it will disintegrate slowly as the plant grows. It can be hard to regulate the moisture of the soil, however, and the cardboard can get very damp and fall apart on occasion.

Or use 9cm plastic pots - those pictured above, far right are from Sarah Raven.

I like to recycle where possible so I have had a go at making some diy plant pots this year from old plastic bottles. I cut the tops off the bottles and wrapped gaffa tape around the 'pot' to block out the light. The top part of the bottle that was removed can be used later to protect the growing seedling from pests. I'll see how I get on with these. They allow lots of depth for root growth. (In this case I had the added benefit of drinking a gin and tonic in the garden too... )

If you try this be sure to make drainage holes in the base before adding soil.

A plastic tonic water bottle cut down to make a plant pot for sweet peas — Tonic water bottle plant pot

Planting

In a 9cm pot or similar, add 3 seeds per pot. Using a pencil or seed dibber, make a hole around 1-2cm deep and add one seed per hole. If using toilet rolls seed pots add just one or two seeds per pot. Water your seeds well until water comes out from the base of the planter - the seeds will need this initial moisture to germinate - and then leave alone on a windowsill or other spot in the house or greenhouse in indirect sun.

Tough love - keep them cold

Once the seedlings are around 1cm tall, put them in a greenhouse or outdoors in a coldframe. The cold will ensure that the seedlings do not grow too fast on top. You want to make sure the roots get some good growth and avoid leggy stems. The cold will slow down the top growth and help the roots develop.

Be sure to protect your seedlings from slugs, snails and mice outdoors. I'm hoping my bottle method will help protect the seedlings if I tape the top of the bottle back on, and I can remove the bottle lid to let air circulate. Or you can use a propagator lid. Mice love to eat sweet peas , so think about how to protect your plants or they will vanish before they've even begun.

Planting out

Don't plant out your seedlings until mild weather has set in sometime from March - May. Dig a hole that leaves enough room for your lovely long roots. Either grow against a trellis or a teepee in the flower bed.

Top tips!!

I asked some experts and here are their top tips.

Liz Stevens said 'my top tip for growing would be to grow in hard, cool conditions to give stronger plants'.

Lizzie from The Rose Press Garden said 'keep cutting as they bloom and make sure you deadhead any flowers going over to ensure a succession of blooms'.

The more you cut, the more you get.

Great advice.

Happy growing!