The time to chill: vernalisation
Not so much a how to, as a little ‘you could if you would like to’.
In my seed sowing guide, I wrote about some seeds needing (and some liking) a bit of cold to break their dormancy. How else would they know that it was spring? Not because it is warm, but because they have been cold and now they are warming up. It is the cold, not the warmth, and then change in temperature that is so characteristic of spring. It’s why I enjoy it so much too. Can you imagine living somewhere without seasons and it was just lovely all the time? Where’s the fun in that?
I have my eye on mid-March for the first big round of seed sowing and it is generally thought that about four weeks is a good time for chilling. Like so much of growing, there are people who are devotees of the stratification, and there are the ‘I’ve never entertained this and it’s never done me any harm’ brigade. I am not going to come down on either side until I have seen the results for myself and so I am firmly bet-hedging this season.
Half of my aquilegia seed is going in damp vermiculite in the fridge and half is being sown now. Maybe it should be a third in the fridge, a third sown now and a third sown when the season of growth is in full spate, but the exquisite varieties that I ordered from Plant World Seeds didn’t come with that many seeds in the envelope.
I do find aquilegia germination a little tricky and so this is worth the time and effort to try and find the right conditions. I have bought at least twenty envelopes of chocolate soldier columbine (Aquilegia ‘viridiflora’) in my lifetime and I have only ever seen one single flower. And even that plant didn’t last very long. Part of the reason for this is that the seed is quite expensive and I had a habit of seeing it in half-price, end of season garden centre sales and giving way to temptation. Aquilegia seed needs to be super fresh. Oh, and it is impossible to get it to breed true so saving your own is tricky. Hence why I don’t stock it in the Gather shop.
Anyway, back to the practicalities. Fridge, not freezer, unless you are chilling Bells of Ireland. You need to be harsh with those babies. Dry cold is no use, it needs to be damp. This means that you can’t just put the seed packets in the fridge, they need a bit of something in with them that can hold the damp. Vermiculite, perlite, or just a little compost.
Damp, not wet. Put a little compost in a bowl and wet it before you put the seeds in. Damp enough to stick to your hands, but absolutely no drips or sogginess. If you squeeze it in your hands, it should only just clump briefly. If you are using vermiculite, just to the point that it sticks in that irritating way to your hands.
Once you are happy with the consistency, add a tiny bit to a sealable bag. You don’t need much. Label. I cannot labour this point enough. Label before you put the seeds in. Add a few seeds. All if you are confident and willing to gamble all on one sowing. Seal carefully. Put in a place in your fridge that it won’t get mistaken for anything edible. Put a reminder on your calendar to take them out in four weeks. I once had a packet of larkspur in the freezer for eighteen months and I only found them when we had a power cut and I had to decant everything to the chest freezer in the back kitchen. Yes, they still grew.
Seeds I am chilling today:
Aquilegias, lots of different colours and varieties. Some seed is older than others so I may have mixed results.
Astrantia
Clematis – I have got some of the brown furry clematis seeds (Clematis ‘fusca’) as well as some C. integrifolia, the non-climbing kind rather tragically named ‘solitary clematis’.
Delphinium & larkspurs
Echinacea, including the last of my Hauser and Wirth sourced ones
Helleborus (Christmas rose)
All poppies except opium poppies, they self-sow for me anyway so I don’t actually plant them
Phlox
Rudbeckia
Sanguisorba
Scabiosa, all the colours
Viola, wild and V. ‘Tiger’s Eye’
