Harry Cabluck wrote: ↑Sun Feb 18, 2024 3:59 pm DE seems to work better than originally thought. The dust does not seem to be a big problem...helps to wear a mask when pouring, etc. Will not go back to using Espoma seed-starting mix. The moisture/lack of air circulation under the starting domes provides an atmosphere that invites edema.

Ingredients:

This product is formulated from 80-90% sphagnum peat moss, perlite, limestone to adjust pH, and yucca extract.

JRinPA wrote: ↑Fri Jan 05, 2024 10:58 pm I love soil blockers. The made in England ones...ladbrooke. I have written about using them a few time over the years. I punch out between 15-25 trays per year of 2" blocks. That is with the 4 block blocker. 50 blocks to a 10x20 tray. So I use that quite a bit. I also have the microblocker that punches out 20 3/4" blocks. That's great for tiny stuff like basil and sometimes lettuce. Then you can transplant tiny blocks or up pot or up block to the 2". I even have the 4" blocker, but that is rarely used. That takes a lot of mix to fill. Most times I have tried to cheat with that big one and use subpar mix and it just doesn't work great.
With soil blocks you want to keep the squares tight against each other so they don't dry out too much. The roots will grow a little into the next block, which is fine, then they just get cut when you cut the block out to plant. The roots don't ever swirl or get long and skinny. They are thick short pipes that hit the ground running.

In general I start a tray in the cold basement under lights, under dome, and on heat. After a few weeks I hope to get them outside. Tomatoes for me are usually in the ground 5 weeks from seeding at about 5-6" high.

I never did much with plastic trays/loose mix. So I was not a transfer to soil blocks, I sort of decided that was the way to go from the start. From what I read on here it seems like a different game compared to plastic trays. I happened to know someone that had tried these and found plastic trays were just easier for them, on their large scale. The hard part I think is finding a consistent mix that works for your growing situation, and taking the time to prep it the same each time.

My mix:
I use the blue plastic squarish maxwell house cans as the scoop - the top cut off, to about 4" high. Each 10x20 uses about 4 scoops.
2 parts peat moss, sifted 1/2" hw cloth (and the quality of that is getting worse and worse each year, waste is getting near 40% volume last year with sticks and clumps)
1 part coarse perlite (luna rock)
1 part vermicompost , sifted 1/4" hw cloth (that is kitchen waste compost pile, then moved to an outdoor worm bin for July to March. By March-May it is finished nicely for blocks. Some worms get through the sift and stay alive in the blocks up to plant out.
You don't want to use compost that is not really well done, as that will promote damping off. That may not be a problem in dry So Cal but it is here in cool damp spring of PA.
1-2 TBSP of lime
mix that up dry, then add 1 part warmish water. Cold water works but won't wet out the peat moss very quickly. Mix and stand 5 minutes, then mix in about another 1/2 part water until it feels right. I have had many iterations to get here but this pretty much works everytime for me.
That mix makes a block with good consistency that punches out cleanly.

I never add any fertilizer or food or whatever, as that is already in the vermiocompost. The first couple years I did use greensand/rockphosphate/blood meal mixed in initially, but I never bought any more.

I have played around over the years with what happens next. Some seeds are better right on top with some more wet mix pressed over. Tomatoes, peppers, eggplant, onion. Some seeds get pushed down into the middle of the block. Corn, squash. Some seeds get a hole pressed and the seed laid in it. Broccoli, cabbage. And some seeds, I have pretty much given up on. Okra with the big taproot - I can start them in blocks and quickly plant out, but it is dangerous to try to grow them for weeks as 2" blocks. The root shoots right through and they damp off in a flash.

The last couple years I also played around with diatomaceous earth used a couple ways for on top. I have not observed a really clear advantage with that.

I also do dense planting at times and transplant directly into fresh soil blocks. Works fine for many plants.

Bottom watering is the way to go for me. Usually not for a couple weeks after starting. I can tell when they need water by the weight of the tray. Better too dry than too wet. They don't start drying out quickly until there are plenty of roots feeding lots of green and by then most plants are just waiting for a good day to plant out. Usually I make a mistake or two every year; doesn't mean dead plants necessarily, but some worry.

Most seeds love soil blocks. It is just a matter finding a mix that works for you. I suppose you could make them without compost and add ferts or liquid fertilizers just like plastic trays. I just have not needed to try that yet. I am wondering at what point I will be sick of buying the junk they are selling as peat moss nowadays, and end up buying some ProMix instead. I've never tried it but it has to be less waste by volume since it is made for seed starting.

CtGrower wrote: ↑Sat Feb 01, 2025 12:42 pm What is the benefit of DE?

zeuspaul wrote: ↑Sat Feb 01, 2025 5:11 pm

CtGrower wrote: ↑Sat Feb 01, 2025 12:42 pm What is the benefit of DE?

As a stand alone seed starter granular DE is sterile, holds water and is well drained. I have only used it in mixes because it holds water and helps with drainage.

Harry Cabluck wrote: ↑Thu Jan 11, 2024 4:44 pm Am using diatomaceous earth (NOT kitty litter) this year for the second time since 2007. Seems to work ok but forgot how much the dust is offensive. Probably will switch back to a commercial seed-starting mix like the one from Espoma.