How to Sow Sweet Peas

How to Sow Sweet Peas

I’m going to sow some sweet pea seed, and we tend to do it here kind of any time really between November and March, depending on when we want them to flower, so if we want them absolutely definitely by mid to late May, for instance for Chelsea week, then we would start sowing November, December, January, but whereas if we want them in September for an event or a wedding, we would sow them March or even April, and with sweet pea seed, if you sow earlier, you do get deeper, stronger roots and a bigger more prolific plant with more flower production. A lot of people soak them overnight before they sow them, but we don’t do that here because we find that really quite a few rot if you do that, so we sow them completely dry. There is one exception, which is if we know we’ve got quite an active mice population, then we would soak them in liquid seaweed fertiliser because it puts the mice off and it doesn’t do the seed any harm.

We always sow our sweet peas into rootrainers, which are these things, and I’ll just explain why, with this, which is some that we sowed a month ago, and what you’ll see is that you’ve got a long, thin profile, four in this envelope and you get eight envelopes in one set, and the other thing is that rootrainers have these channels down the side, and that directs the roots, so they don’t go twiddly twiddly round the edge of the pot, they get directed straight to the bottom of the pot. The roots are then air pruned and you get lateral rootlet formation more quickly, so that’s why they’re really, really good for sweet peas.

Two seeds go into each cell. So you put them into the palm of your hand, and then just dot them on the top, and this is how I sow any seed, you don’t push them down initially, you dot them onto the top of the compost, and then press them down, and I always do it in that order because then I can see exactly where I’ve gone. So then, I push them down to that knuckle, which is about on and a half inches deep. And then I’ll put these somewhere ideally with a basal heat, but it’s not absolutely essential, and these will germinate in about ten days. And then leave them to grow on, for about – in the winter it’s normally about three weeks after that – until you get to the three leaf stage, and I’ll explain what I mean by that, so what I’ve got here is one pair of leaves, two pair of leaves, three pair of leaves, and really often you know when you’ve got to that because you’ll see the first of those twiddly bits starting to form. That is the sign (three pairs of leaves) for pinching out the tip, and you do that by just pinching here, and you remove the apical shoot. What that does, is the growth hormone, it always pools at the tip, and that makes sense because it’s a climber and it’s making it grow upwards, but by removing that, the growth hormone then pulls back down into the root, and then pushes out what’s called the auxillary buds, and you get a short, stocky, strong growing sweet pea.

Once you see the roots have filled the whole of the cell, move them on. This is perfect because again it's long and thin, so fill that with compost and then put in. Open up your rootrainer and the great thing about rootrainers is that they’re really easy to just flip one plant out at a time, lovely root ball. Slot that into your one litre pot and fill with compost around it. Re-label, water, and leave that to grow on, once the roots have filled this pot, I plant them out. We also use rootrainers for other legumes like broad beans and runner beans because they also thrive with a deep root run, and we use them for any cuttings really, where the plastic lid turns the whole rootrainer set into a mini propagator.