Soil blocks VS paper pots and other seeding alternatives to plastic pots

Hello everybody,

Like many others I guess, over the last month I have been flooding the window sills with all sort of pots, waiting for my seeds to germinate. I recycle all my pots from year to year, so quite a bit of disinfecting required obviously.
I even tried some tiny bags which are just perfect to fit 40 or so seeds in my little propagator. But I then found out that the bags are not truly biodegradable, and not all plants manage to punch through with their roots, so I spent quite a lot of time cutting them open and repotting them.

Germination rates have been really good I have to say, only one marina di chioggia squash, three sunburst patties and two early bird sweetcorns failed, so overall 97% or so, I cannot complain.

Still, I was looking into soil blockers and paper pots makers.
I found one soil blocker (small cubes for starting seeds, and larger ones to plant directly) At £40 the kit is a bit expensive, I am not sure how easy and fast is to make the blocks and if it can be done with simple potting soils or rather needs perlite too, but I like the idea in principle.
Also, I saw paper pots makers for £15 or so on amazon. Actually, looking at the shape, if I take out my wood lathe probably I could copy the design easily enough.

What do you think about soil blocks and paper pots?

Thanks for any advice!

Aldo

 

I never wash anything ... if I had anything diseased I'll chuck the whole thing away ... but FingersCrossed has never happened. I do wash the seed-sowing trays, but only to get rid of the crust that builds up round them. As soon as a tray is pricked out the next batch is started off. I reuse the seed-sowing-compost (microwave for 10 minutes - haven't bought any new for 5 or 10 years ... but not 100% get recaptured ) back into the same seed trays. And potting on the 9cm go into 1L and the 9cm are immediately reused for potting-on ... no washing I'm afraid.

maybe not the best recommendation! but I do think too much concern can be made of pot-cleaning.

I roll a sheet of newspaper around an aerosol can - choose Can of appropriate diameter for the pot you want, and make a mark on it for whatever "height" of pot you need. Probably better suited to things that "get on with it", but the pots are surprisingly resilient. Here's how I do it:

How to Make Pots from Newspaper

I definitely think that is a good solution to avoiding Plastic.

 

@Kirsty Thanks!
I did considered microwaving the soiling compost to reuse it, actually.
My only doubt was that I read that sterilizing substrate can leave a door open to some very nasty molds, which are normally kept at bay by microorganisms which sterilization removes.
But then, I read that about mushroom substrate, probably for potting soil is not an issue.. Given you have done then succesfully in the past, I will give it a go.

 

I have been using soil blocks for years. It takes about 5 minutes to make a trayful of the 2 " blocks. Approximately 30. I buy my potting soil at the end of the season to save money. I used to bake the old soil in my outdoor wood oven but found it pretty time consuming.

 

Thanks Lori!
Do you add anything to the soil when making the blocks?
I have seen a guide suggesting to mix one part of peat, two parts of vermiculite and two of compost.
The soil I normally buy is what my local gardening center uses for the decorative baskets and tubs they prepare for pubs and shops, which last all season without adding fertilizer. It works well for seedlings too in my esperience, and it does contain some peat and very fine vermiculite, but in quite small amounts. If the blocks hold their shape, I was thinking of trying just with that without adding anything else.

 

I don't think you need to add anything. I believe there is specific "mix" sold for Block Making. That might "bind" better ... but I would start of just trying with regular compost and seeing it the blocks fall to bits Videos I've seen it looks like the compost is very wet, when the blocks are made.

 

Hi Aldo. Nice to see you again.

I am a bit confused here. If anyone has plastic pots, then why not continue to use them. My understanding is basically to avoid producing more.

Relating to sowing beans etc. I always advocate to use what method suits you. In the case of beans and peas. I have always soaked them at least overnight, then sown them direct to where they are to grow. Give them a really good watering in. For peas, the protection of a cloche is useful. Best wishes.

 

I just buy good potting soil and mix to a thick consistency with plain old water. Too much water and yes, they will fall apart. Just looked it up- I bought my block maker in February 2013 and it has been wonderful. I did try the paper pots before ordering that and the paper actually looked like it was going to get covered in mildew or some other nasty thing and yes, it took forever to disintegrate.

Sorry @Kristen, whatever you read, I'm calling BS. If you're going to quote problems in order to contradict my suggestion, from experience, then please do so from your personal experience. I've never even heard of a special compost for this. If there is one, then someone came up with the name to hit a certain market and sell more of the same old same old.

I did make some blocks with special soil but that was because it was for carnivorous seeds. That's about 4 months ago and the blocks are still holding together, drawing water and I have 3 seedlings now

@Aldo , it's not their forever home. Just enough to get them to sprout and grow to little seedlings. Some might need to go into pots after a few weeks if they get too big to wait for last frost to be done and to plant out. This way, you only pot up blocks with seedlings. Blocks with failures just get reused. No plastic, no waste.

Whatever you choose, I wish you success!

 

I did no such thing ... I just made a passing comment, unrelated to anything you said.

I did a Google and there most certainly has been Compost formulated specially for Block making from the likes of Scotts (who own companies that make most horticultural products). I don't know if it is still generally available but it is still for sale, in Scotts branded packaging, on eBay. There are other brands available such as:

https://www.fruithillfarm.com/klasmann-organic-blocking-compost-peat-based.html

KLASMANN ORGANIC BLOCKING COMPOST/SUBSTRATE
"A compost specially formulated for making soil blocks with the aid of a blocker tool €9.85 / 75L"

Ditch the pots, use soil blocks! | Chelsea Green Publishing

"For soil blocks, this special growing medium is a blocking mix. The composition of a blocking mix differs from an ordinary potting soil because of the unique requirements of block-making. A blocking mix needs an extra fibrous material to withstand being watered to a paste consistency and then formed into blocks ... A blocking mix also needs good water-holding ability, because the blocks are not enclosed by a nonporous container"

 

@Kristen fine. Now you are quoting/repeating their BS again. It is their propaganda to market something that they want to sell even though it definitely not necessary. I personally have made soil blocks for 7 years with ordinary potting soil and had zero issues and a pretty good germination rate.

I see no point in advising anyone to spend more than they have to. Not everyone has a large gardening budget.

 

Hi Mike,
thanks, nice to hear from you again too
You are right that, given after all I have a bunch of pots and I reuse them over and over, I could just stick to that.
But, because our house is very tiny, using lots of pots for germinating seeds takes too much space at times. I tried the bags and they actually work well, taking very little space with good germination rates. Was it not that that they are not biodegradable and the roots do not punch through easily at times.
So I was wondering if the soil blocks could work, the smaller size are, well very small, so I could fit quite a few on my window sills and perhaps transplanting would be less hard on some plants.

As for the beans, do you advise pinching the tip to protect them from the blackfly?
Are they very succeptible to slugs, by any chance?
It is my first year growing beans, so I am very curious to see how they will turn up.

 

Thanks Lori.
I was wondering how long it would take for paper to disintegrate actually, and how hard would be for some roots to punch through it.. I have seen paper used as mulch in some permaculture video and allegedly it can last all season before starting falling apart.

Do you use both the tiny blocks and then the larger ones?
The block making kit I have seen comes with two contraptions, one to make very small blocks with an indentation for the seed, and one to make larger block with either an indentation for the seed or a square hole to fit exactly one small block.

 

@Aldo I use the 2" size. It works very well for me. I start my chillies, annuals flowers, vegetables, well everything in them. There is no damage to roots from pulling them out of small pots and depositing in larger ones. No dead cells to try to empty in between the successes. I bought another block maker last year for one of my sons, the one who is now an enthustiastic gardener and he hesitated to try it at first. Now he says he is, after the first couple of tries, never going back to the little plastic cell packs.

It is not for everyone but I really go for it because it uses no plastic (until germination and time makes you pot it up) and you're not wasting space on dead seeds. When you're a regular back yard gardener like me, you try to compact in as much growing to your growing real estate if you're like me.

To each their own

 

Forgot to tell you that I use a small spatula to move my blocks around. Easy peasy