I do a lot of seed starting, beginning now with spring flowers, and then in March all our summer veg, and then again in August for winter veg. I go through a lot of seed mix and I have used and re-used those flimsy plastic seed trays for years. There’s a lot of problems with those seed trays; they tear and break easily, you have to dig out the seedlings to pot them up which often hurts the roots, and they don’t sit well in the flats that are made to go with them. They’re standard: Everyone uses them, but everyone rather dislikes them. Me especially.
I’ve experimented with other ways of starting seeds. You can put them in half an eggshell, you can make little paper pots for them, you can buy ‘cow pots’ made out of manure. You can start them in peat pellets, but peat is a very unsustainable medium. I just wanted a better way. And then I started hearing about soil blockers.
People seem to have great luck with these little machines. I figured it was worth a try and asked for them for my birthday. Tom ordered two sizes for me - one is a block of 3/4” squares - there are 20 of those squares in the block. The other is a block of 4 2x2” squares. I experimented with them today to start Iceland Poppies, along with some other seeds. The tiny blocks were good for the poppies because I just scattered the seed over the whole block, those seeds are so tiny. The larger blocks are good for bigger seeds, like sunflowers or beets.
The trick is to really saturate your soil mix. I used an organic seed starting mix made of shredded coconut coir and perlite, with organic worm castings mixed in. You really add a lot of water and let it sit awhile to hydrate. This makes it easier to form the blocks. I have to say that the larger blocks were MUCH easier to make than the small ones.
My examples are not terribly good because I need to put the soil blocks closer together. Otherwise when you water them, they spread all over the place. I’ll just use a spray bottle on these, but in the future, the soil blocks will cover the trays with no gaps between blocks.
One really nice thing about these soil blocks is that you don’t disturb the roots when you transplant them, as you lift the block of roots out whole. No digging, no pricking out, no separating roots.
A lot of folks make wooden trays in which to hold these blocks; three sided trays so the water can run out the other side, and you can slide out the blocks to plant them in your beds. I knew we did not have a lot of time to be building wooden trays; hopefully we’ll make some in the future. Meanwhile I bought some trays I had seen at the Heirloom Seed Festival in Santa Rosa in September. They are made by Bootstrap Farmer. They are super sturdy and will last for years. Plus, they come in fun colors.
The ones on the left are called ‘microgreen trays’ - see how they have a slight bit of drainage in the bottom? These are good to put the soil blocks in. Then I set that tray on top of a regular tray, like the ones on the right, to catch any water, which I reuse. I’m really happy with these trays. Not cheap, but certainly will last longer than those cheap ones.
I seeded a bunch of different flowers today, and those trays are in the greenhouse. It’s really to early to do much of anything, but I wanted to see if I could get those (notoriously difficult) Iceland Poppies to germinate in the next month, so I can plant them out as soon as it starts warming up in February. I also sowed-in-place a million California poppy, Clarkia, Phacelia, and California bluebell seeds all over the pollinator gardens. Hopefully we’ll have a good show in a month or so.