By Elaine Wilshusen, Somervell County Master Gardener
If you enjoy getting a jump on starting your vegetable or flower seeds indoors, you may have heard of soil blocking for starting seedlings. I have started my vegetable seeds indoors for years using “peat pots”, seed starting soil, heating mats and grow lights. I had never heard of the soil blocking technique until recently and I am going to give it a try this spring.
Soil blocking for starting seeds involves using a specialized type of mold to form blocks of lightly compressed soil into a cube shape. The soil mixture is different from typical potting soil, as the blocks will need to hold together while the seedlings are growing. Each cube holds one seedling. There is no additional plastic container or “peat pot”. The block serves as the growing medium and container and they are placed on a tray while the seedlings germinate. The blocker molds come in various sizes and can make as many as 20 small blocks or just 4, depending on the type of seed/plant and the length of time they will need to remain indoors before planting. Ideally, they are best utilized to get the seedlings outside in the ground as soon as possible. The soil mixture is different from typical potting soil, as the blocks will need to hold together while the seedlings are growing.
I will continue to use a seed starting heat mat underneath the trays to maintain adequate heat for good germination and use a grow light while the seedlings are indoors.
The purported advantages to this technique include:
- Reduces the use of plastic and/or peat.
- The seedling roots spread throughout the soil cube more uniformly, are stronger, and do not become root bound if transplanted in a timely fashion.
- Transplants establish themselves faster.
- Takes much less space to grow many more seedlings than the alternative methods.
And certainly, being able to start your own seedlings, no matter what technique, allows you an almost infinite choice of vegetable and flower varieties instead of settling for what is available in the nurseries.
So this spring, I will try something new and continue my “traditional” method as well. …just in case! I will post for the next few months on the good, the bad, and the ugly of my experiment. Maybe it may be something you will want to try as well!
Small soil blocker…makes twenty 3/4” blocks.
The underside showing the little divot to accept the seed. A wetter, more solid soil mixture will be used to place in the mold to form the blocks.
My “traditional” supplies. Missing in action is my grow light. I will still use heat mats under the soil blocks and the grow light.
References:
www.chelseagreen.com
www.thegardenersworkshop.com
Info on “traditional” seed starting: www.seedsavers.org/starting-seeds