Some perennials and even some annuals are happiest if sown in the autumn and overwintered, ready to grow on when things warm up a bit in the spring. This mimics more closely the normal lifecycle for these plants. 

Happiest of all, this means I have an excuse to bring forward one of my favourite garden tasks – sowing seeds. This is not a complicated process – at its most basic you sprinkle the seeds over some compost and lightly cover them, depth varies according to seed type. That’s what gardeners have been doing since the year dot.  Watering correctly is then the main challenge. Not overwatering so that the compost becomes waterlogged, putting the seed or seedling at risk of rotting off.  But also not underwatering so that the compost dries out. Most seeds will not germinate if dry, and seedlings will quickly succumb if allowed to dry out. I read a lot last year and settled on an approach for sowing seeds, which both saves a lot of space and takes the guesswork out of watering.  I fill a 7cm square pot two thirds full with multipurpose compost then top up to the rim with vermiculite. Generally, I sow the seeds on top of the vermiculite. For very small seeds they’ll just be watered in, for larger seeds I gently stir them in to the top layer with anything handy, a pencil usually. For pea size seeds, a thin layer of vermiculite goes in first, on top of the compost. Then the seed, then cover with vermiculite to the rim. 

This is all advice given by Peter Thompson in Creative Propagation, one of my main go-to resources for propagation.  It’s a fairly old book now, getting on thirty years, but a goldmine of useful practical knowledge.

Vermiculite is used because it remains wet when watered but the excess drains away. This means that I can just water away without fear of overwatering. I use small square pots because they take up much less space than a seed tray – 15 fit in the space of one standard seed tray. A small pot like this will hold up to 200 seedlings quite happily, easily enough for a typical seed packet, whereas a seed tray has room for up to 2000, way more than needed for most seeds.

Here’s what I’ve sown recently.

  • Sweet peas, three varieties
  • Hollyhocks, two varieties
  • Calendula ‘snow princess’
  • Aubrieta 
  • Coleus
  • Nigella
  • Nemophila
  • Lobelia tupa

Here they are about a week after they were sown, all nice and snug in the heated bench. If I didn’t have this facility they would be indoors on a sunny windowsill.

I sowed these on 10th September and some have germinated fast, I have already pricked those out into either pots or trays depending on size. 

It is tempting to prick out all the seedlings but this way lies madness. I know from experience that this results in far too many plants to manage. Whilst a few spares is prudent, one rarely needs 60 of anything, even allowing for plant sales and giving away to friends and family. Thinning out to keep the strongest seedlings is just part of the process of getting a sensible number of good plants. I have managed to restrict myself to 10 sweet peas of each variety, no more than 15 hollyhocks of each kind, and a half tray of coleus. This is still too many, I will further thin out when time to pot on, discarding any weaklings. 

As a bonus extra I found some seeds on my exochorda macrantha shrub, a pity bench rescue from a few months back. They do best when sown fresh, so I did just that. In this case I used a larger 11cm pot because it will live in the cold frame for the winter – I find the smaller pots are prone to getting knocked over. I’ve covered it with grit to keep out undesireable stuff including, but not limited to, sycamore seedlings which are a scourge in my garden right now.

I love the process of growing plants from seed, if you’ve never done it, give it a try! 

I’ll be back soon, with more propagation monkey business.

*header photo of coleus is not mine, it’s from a seed catalogue. Hope mine look something like that!

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