Sunday, March 14, 2010

Potting Up Soil Blocks

Friday morning I was busy in the laundry room where I keep my seedlings. My lettuce seedlings had their first true leaves. The roots were coming out of the bottom of their little tiny soil blocks. It was time to pot them up. I've had questions about what soil blocks are and how I use them. So I'll use my lettuce as an example.

Small, Medium, and Large

I have three soil blockers. The smallest one makes 20 blocks all 3/4"x3/4x3/4"". They are so tiny. When I use these blocks I put just one seed inside each. If they don't germinate (like you can see for some of the lettuce above), they just get tossed. They don't take up much soil so it isn't much of a waste. They are great for using every little seed you have, but they dry out very quickly. I have to water them very often compared to the bigger blocks. These little blocks pair with my largest blocker. These larger blockers make soil blocks 2"x2"x2". Mine have inserts (which you buy separately) that punch out holes for the 3/4" blocks. So once they have a true leaf, I just put the little blocks inside the bigger ones. Potting up is so easy.

The medium ones are 1 1/2"x 1 1/2"x2". These are my favorite size. The 2" size takes up a lot of room. They can be crammed five across, but it doesn't leave any space between them (I need one that is just 1/8" short of 2"), so the roots will grow together into each others blocks. This is not ideal. For some plants I'll have to place them only four across which takes up a lot of space. The 1 1/2" blocks fit six across with a lot of space between them. Perfect. The issue with these is that I always put in at least two seeds so I have to thin. Not really much of an issue. I will still use the other ones for things that need a bigger pot, like tomatoes and peppers. I'll also use them for things that I don't know the germination on or things that I don't have much seed for.

Soil blocks have a great advantage of not having transplant shock (just like newspaper pots but faster to make). I don't have to wash out pots every year. No plastic, which is always good. Nothing thrown away. Their disadvantage is that they have a learning curve and if you are too rough with the blocks they can fall apart on you. I use tongs to move mine and bottom water so the soil doesn't get washed away.

Here are my lettuce seedlings all potted up. I have a whole box of Popsicle sticks from when my kids were young. I use them to label all my blocks. In a couple of weeks they will go into the garden. I think lettuce from now on will stay in the 1 1/2" blocks and I'll save the bigger ones for things that need it. They take up way too much space. But these will be outside quickly so it isn't too much of a problem this time.


  1. Great post, I have been wondering about the stability of the soil blocks and decided not to purchase the block maker this year, but have been watching those of you who did it, and I think I am sold on it for next year!

  2. Wonderful to see those sweet little seedlings! I have never used a soil blocker. Interesting post!

  3. That's great. I have been happy with flats, but you make a great argument for blocks. Must sow some more lettuce. . .

  4. I just get four across, I need to make a smaller one. I did have one I made from a pill bottle, but It got lost somewhere, and there was just something wrong with a round block ;-) I do wish I had the tiny one and the insert for it. I managed to get all my markers mixed up last year, so this year I'm using duct tape on the sides of the containers.

  5. The more I read about yours and others experiences with the soil blockers the more I am tempted to give them a go. Maybe next year I will do a homemade one like Annie's Granny's and do it on a limited scale to see how I like it.

    The lettuces look beautiful.

  6. I'm gonna have to look at a photo of that soil blocker sometime on the internet. I know I can make a pretty good one, but haven't really got the mechanical concept down yet.

  7. Thanks for your insights on using the soil blocks. I've been leery of them because I'm concerned that the blocks will fall apart. Thanks for giving me some reassurance. I will try them for my next batch of seed plantings.

  8. I tried to put the mini block insert into my 2 inch blocker last night....what a pain! Hopefully, it will be easier once the screws loosen up through constant use.
    What other crops do you use with the mini blocker? The lettuce worked great for me but the asian greens looked awfully leggy when started in the mini blocker.

  9. Very interesting, Daphne! I've never used the blocker.

  10. I have the same concerns as KatieLovesDogs, your insight on using the soil blockers is valuable, now if I can talk myself into mixing up the soil I'll be in the soil blocker band wagon.

  11. I keep humming and hawing about soil blockers because of the intial investment but they sure look good!

  12. Erin, lol I hope you like it. It does have flaws, but so do the traditional flats.

    Carol, thanks

    Stefaneener, I'm hoping my wintersown lettuce will be my next wave after these.

    Annie's Granny, you are always losing things Granny. You are even worse than me. I can never remember where I put things, but I'm pretty good about having a spot for things and putting them back. It was a hard learned lesson, but I try. I've thought about masking tape on the sides too. But I figure I have about a thousand of these sticks so why not use them up.

    kitsapFG, that is a good idea. It would tell you if you like them before investing. Last year I just bought one to try it out (the single 1 1/2" blocker). I was afraid to get the whole set because I might not like them. But I did. Now I love them. Just remember that the homemade ones are pretty slow since you have to do them individually.

    EG, lol yup I'm sure you could make a really nice one.

    Punk Rock, thanks I think, google translate is not all that great at times.

    KatieLovesDogs, they can fall apart, make no mistake about that, but if you are careful (especially about watering) they don't. I made some tongs to move the blocks around and I think that helps a lot. Also I make them in one place and move them to another before planting up. If they were weak they don't survive that initial trip (maybe one in twenty for me now, but more earlier as I was learning), I toss them back in the soil mix.

    Thomas, lol I know what you mean. I wish they came with the insert in . I'm not removing mine though. It will stay with the little inserts in that size. I have the smaller blocker if I directly seed. My Asian greens will all by in the 1 1/2" size.

    Kimberly, I do love them.

    Mac, lots of people use straight seed starting mix from the store. I don't know how it would work, but I haven't heard any complaints about it.

    Ottawa Gardener, personally I think if you don't want to spend a lot of money on them you can just get the 1 1/2" blocker and nothing else. I think it is a better size than the 2" one. You would need to pot up tomatoes and peppers into something larger (last year I used newspaper pots), but not much of an issue.

  13. I'm doing most of my starts in the soil block this year too. Just about everything's growing fine.

    Just a couple quick questions. How old are your lettuce plants in this photo and what's the longest (or maybe tallest) you've kept your seedlings in the soil blocks? My peppers are doing especially well in the blocks.

  14. Cheryl, the seedlings are just little things - probably around two weeks old. How long they stay really depends upon how fast they grow. I like to get them out when their roots have taken over the block well. I'm probably going to give my peppers about six weeks and my tomatoes about four weeks in the 2" blocks.