Making Your Own Seed Starter

I’m tired of buying seed starting mix. The stuff is way more expensive than it should be, in my opinion.

I need to get some cabbage seeds started for the fall. So instead of buying seed starting mix, I made my own.

Commercial seed starter is usually made from some combination of peat moss, compost, perlite and/or vermiculite. It’s typically sterilized by heat to kill any plant pathogens in the soil. Peat moss has antimicrobial properties as well. This is kind of a double-edged sword in my mind, because I want healthy, living soil full of beneficial microorganisms. But any harmful microorganisms in the soil could kill tender seedlings.

I can understand why commercial growers want sterile soil to start seeds. They need to maximize profits by making sure every seed they start grows into a marketable plant. I’m just a backyard gardener. So I’m not too concerned about that.

I do have plenty of homemade compost and a half a sack of old perlite. So that’s what I’m using. I ran across a recipe for homemade seed starter mix that called for the following:

• Four parts compost

• One part perlite

• One part vermiculite

• Two parts peat moss. 

As I mentioned earlier, I’m not a big fan of peat moss due to its antimicrobial properties. Coconut coir is a good alternative. It’s made from the fibrous husks of coconuts. It’s often used as a liner for hanging baskets. You can buy it in compressed blocks. When you soak the block in water, it expands many times in size and becomes crumbly like peat moss. I’ve used it before, but I don’t have any right now.

I’m also out of vermiculite at the moment. So I’m just going to use perlite and compost.

My compost pile is full of insect life. I can see lots of little critters crawling around in it. I’m sure there are many more microscopic critters that I can’t see. I’m not sure if this is a good or bad thing. I used a coarse screen to separate chunks of woody debris that hasn’t broken down all the way. The screen also filtered out some of the larger critters.

I didn’t accurately measure anything, but I aimed for six parts compost to one part perlite. Hopefully it works. I filled some seed trays with it on Tuesday and planted my cabbage seeds. I’ll let you all know how it goes.

If you try to start your own seeds, whether using commercial seed starter or a homemade mix like mine, make sure to amply moisten the soil before filling the seed trays. If you fill the trays with dry mix and then water the soil, you’ll end up with dry pockets in the seed tray. No matter how much water you apply, those pockets never seem to wick up the water. You’ll end up with poor root systems and the seedlings will struggle to survive.