perlite or vermiculite... soil block mix

[birdermom]

Reading conflicting information on which to use in mix...perlite or vermiculite? What have you used to make the blocks?

[Stvrob]

I used to use leaf-mold with worm cast, some peat moss and just a bit of perlite. Also a bit of limestone and course phosphate. I felt that too much perlite made it crumbly. I don't generally use vermiculite for anything so I can't comment on it.

[birdermom]

Very limited here in the rural area and the local store only had vermiculite. I read to use that instead of perlite because it was "smaller" and the blocks would hold together better. Also recommended to add green sand, rock phosphate, and blood meal...just small amount.

[Stvrob]

I just basically added stuff I had around and experimented. I have lots of rock phosphate and course lime on hand as I work around drill rigs and the formation right on top of the aquifer is loaded in it. Plus I have 2 giant bags of perlite I bought on clearance about a year ago, and all the leaf mold I can rake up from the woods.

[Cole_Robbie]

Perlite holds mostly air, vermiculite holds mostly water.

[FarmerShawn]

The mix I use, Vermont Compost's Fort Vee, has neither. It's mainly their own compost, peat, and additives for minerals. You can see the ingredient list on their website. I can attest to its ease of use and effectiveness, both for blocks and for potting up. If I was to make my own mix, I'd follow that list as best I could.

[birdermom]

If vermiculite holds mostly water than that doesn't sound like something I would want...may cause problems for the roots.

[Cole_Robbie]

Well, peat or coco-peat does the same thing. I have good results with vermiculite. I have used it to start seeds, and the plants do well. I buy the stuff that is sold as insulation in 3 cubic ft bags.

[Stvrob]

Just try it and see. Im sure it will be fine. Since its not in a pot no root will ever be far from air.

[birdermom]

Sounds good...thanks for responses

[Rajun Gardener]

I use MG potting mix with moisture control & nutrients and not have to fertilize till they go in the ground. Some people complain about little sticks but it's not seed starting mix and it works great for making blocks, just add enough water till it holds together and you're set.