No, not a large female pig!

I have failed. I have succumbed to the overwhelming temptation to sow all the seeds I got from the Hardy Plant Society seed exchange the other day. Gorged myself. I should have, indeed I intended to, spread the sowing out over a few weeks to avoid a log-jam of time-consuming pricking out later on. Can’t help myself, got carried away. It’s fortunate that they didn’t all arrive at once or I may have sown over 50 varieties in one hit in a fit of sowing. Never mind, hopefully some will be slow germinators. At least they are not taking up much space.

As described in an earlier post on the maths of propagation, it is tremendously inefficient in both space and compost terms to sow a few tens of seeds in a standard seed tray which can hold hundreds or even thousands of seedlings. I am therefore using 7cm square pots, 15 of which fit in the same space as a standard seed tray, see below – 15 pots jammed into a green full size seed tray.

Frugal dougal

In some cases of larger volumes of 1 seed variety I have split them across two pots, but I probably didn’t need to.

In the past, I would have used general purpose compost for sowing seeds, maybe seed compost if I was feeling flush. This year, following the guidance of Peter Thompson, see book review here, I am sowing in pots that contain a layer of general purpose compost about 2/3rds full, topped up with vermiculite to just below the rim of the pot (perlite, cat litter or other clay or crushed brick product would work too). The seeds are sown directly on top of the vermiculite. Most seeds, being tiny, can simply be watered in with a fine rose. Larger ones can be “stirred in” to the top layer with a dibber or pencil, then watered. Pea-sized seeds should be placed on top of a thin layer of vermiculite then buried to just below the rim in more vermiculite. The vermiculite serves the following purpose:

  • Drains surplus water well but remains moist, making it hard to overwater.
  • Allows air to circulate, getting oxygen to roots
  • Open structure, easy for the teeny plant to put on roots
  • Stops small seeds swimming to the corner of the pot in a sieved-compost soup when watered
  • Prevents colonisation by liverwort and other spore-born greenhouse nasties
  • Protects vulnerable parts of seedling from damping off and other fungal attack.

The main benefit of this method, I think, is that it makes watering very simple, no guessing.  Just water freely, with a fine rose, and the excess will quickly drain away. Watering is the hardest thing to get right and germinating seeds and seedlings are vulnerable to both underwatering and overwatering if sown in peat-based compost.

I’m conducting a little trial comparing seeds sown like this vs seeds from the same packets sown just in compost and I’ll post on that separately.

Here they all are in all their glory:

Save space when sowing seeds.
Serried ranks of sowing joy

I have been playing with the label printer  – the pots are all very neatly labelled. It is a bit more of a faff than just writing but hopefully won’t fade, and I also hope that they stay stuck!.

Neat and tidy, tidy and neat!

If you needed any more convincing on the economics of using the smallest container suitable for the job, the picture below shows a direct comparison. There are 20 sowings in the small pots, taking up about 60% of the space of 5 sowings I did last year in half-sized trays. Had I taken the same approach this year, I would very quickly be out of heated propagating space.

Space economy

 Vermiculite or perlite is quite pricey when bought in 5 or 10 litre packs in garden centres. I buy it in bulk in 100 litre bags for about 25 quid on Amazon, very good value in comparison at less than 25p a litre, compared to more like 80p a litre when bought at B&Q, say. A 100 litre bag does me a whole year. Vfm!

I’ll be back, with more sowing excitement and details of trials.