Sweet peas are one of those magical flowers. The scent alone merits their inclusion in any garden and the fact that you can sow them in the darkest days of late winter makes them all the more special. If you are thoroughly over the gloom and dreaming of spring by October (and I know I am), then sowing sweet peas will gift you a lift and hope. A few hours with your hands in soil is likely to be just the thing. 

When

This brings me to when to sow. I have always sown at three different times: October, Boxing Day, and March. However, about six different people came up to me at parties this summer and used the opportunity to rave at me about autumn sown sweet peas and how, once you’ve tried it, you never go back. This does make some sense; sweet pea flowering is triggered by day length and you do really want good big plants before they start trying to bloom properly. That said, mine were six inches tall until about July this year, and then they took off, and managed to reach eight feet whilst flowering at the same time.

Anyway, Roger Parsons says, South Coast (including the West Country), the last week of October. (Patience has never been my strong point.)

Midlands and the North West, middle of October.

Further north than that and you are looking at winter, rather than autumn sowing, January.

Scotland, and there are a lot of Scottish Gather members, mid-February.

How many seeds to sow

My seed envelopes contain at least ten seeds, usually slightly more. I count by eye and so it is always easier to just be generous. Unless you are a professional flower farmer, this is a lot of sweet peas, you will get a lot of flowers, and need a lot of room.

I suggest doing a few of each colour in October, a few more at Christmas, and then one last sowing in the spring. It is good to have spares in case of mice and staggering sowing means you get a much longer flowering period than if you sowed everything at once. 

In case you hadn’t heard, I am going all in on the sweet peas next year. I’m putting all my chips on the table, and if all goes to plan, there will be at least fifty of each of the forty or so varieties I am growing. I’m going to keep going until I run out of pots or beds to plant them out in, whichever comes first.

Soaking 

There is always a bit of a debate about pre-soaking seeds before sowing but I hold a pragmatic view. If the seed is over a year old and looks a bit wrinkled, soak it. If they are plump and look smooth and round, they probably don’t need it; the initial watering will suffice. I hadn’t quite realised until this year that sweet peas vary quite so much in their appearance. Flora Norton can best be described as a scruffy seed (soak). Piggy Sue is, predictably, plump, round, and perfect.

You will need:

/ Peat-free compost. Not seed compost, a good multi-purpose 

/ Cardboard inners or good quality plastic root trainers

/ A container to hold the inners, one of those plastic trays that mushrooms come in is perfect

/ Labels

/ Seed

What to sow in

Fill your pots with good quality compost. Sweet peas produce tap roots, so they do need a bit of depth underneath them. This is why cardboard tubes or root trainers are better than small pots, but the deeper 9cm pots can be used if that is what you have. 

It is remarkably fiddly to fill tubes and compost does tend to go everywhere. You can either put the tubes in the container and try and fill them in situ (this does mean you get a lot of compost in between but that’s not a bad thing, the roots will come through the cardboard before you plant them out) or put the tube into the bag of compost and fill it there, keeping a hand over one end.

How to sow

Put two seeds in each tube, three if you are using the 9cm pots, making sure they are not buried too deep. You are aiming for about a centimetre. I find dibbing with a pencil and dropping the seed in is incredibly satisfying, but it is hard to keep track of the depth and everything sinks again when you water. Filling with compost to very nearly the top and then adding the seed and covering is safer in terms of knowing how deep they are, but also doesn’t compact the compost.

Label. Label every single one, even if you have to cut up some plastic milk bottles. You will never regret doing it, but I promise you will if you don’t.

Watering

Water very gently but very thoroughly. When I say gently, the water will bounce out of the container and splash everywhere, particularly when the compost is dry. Do it in a sink or outside. The first water should be quite a comprehensive one as it takes the place of the soaking step that we have missed out (if you have) and there needs to be enough moisture in the compost to soften the seed coating.

#1 seed sowing tip 

The mantra to remember for most seeds, but particularly sweet peas, is warm and dark for germination, cool and light for growing on. Around 15 degrees Celsius is about right according to the experts but I think a kitchen windowsill, or any place out of a draft indoors, is fine.

Growing on

One of the most important reasons for doing this indoors is that (hopefully) you don’t have mice inside the house and mice love sweet pea seeds. Do everything you can to protect them from mice.  

Keep them moist but not wet. Once the shoots are up and through, get them straight out in the cold. If you mollycoddle them, you get weak, leggy plants. When I say cold, a cold frame or an unheated greenhouse. If you don’t have any shelter at all outside, do not attempt autumn sowing because you’ll be tempted to keep them in the house too long and you’ll end up with great straggly things that never come to anything. Just start them in February instead.  

There is more to sweet pea growing, but this is all there is to sowing. Let’s talk again in February.

The shop is open. Happy Sweet Pea Sunday to you.