|Seed Starting Mix
You have decided to plant seeds indoors.Â In the stores you find different bags of commercial
soil-less seed starting mix. The labels list such ingredients as peat-moss, sphagnum moss, coconut coir, vermiculite and perlite. Some have added minerals, fertilizer and wetting agents or hydrogels. How do you choose? What are the best ingredients? How do you make your own?
Let start from the basics. All a seed needs to germinate is a consistent balance of warmth, moisture and air. Any medium that provides that environment will promote germination – a damp paper towel, warm soil, compost or a soil-less starting mix.
Commercial mixes use non-soil ingredients because they are easily available, clean to handle, remain moist and drain well. Of the common bulk ingredients, peat-moss (sphagnum moss) is mined from non-renewable peat bogs. It tends to resist wetting and dries fast so other ingredients are always added. The alternative, coconut coir is increasingly popular. It comes from renewable sources and wets more easily. However, unless it is processed well, it may contain excess salts and lock-up essential minerals. Look for salt-free buffered coir in the mix.
- Vermiculite is a heat treated mica-type mineral that helps retain moisture.
- Perlite is a white popped volcanic ash that lightens the mix and creates good drainage.
- Minerals and fertilizers: these are needed by the seedling as it starts to develop. Choose good quality organic nutrients and not quick-acting chemicals.
- Wetting agents or hydrogels are manufactured polyacrylamide gels that expand and hold water. While deemed “safe”, these gels may contain or breakdown into a neurotoxin and carcinogen called acrylamide. My recommendation: DO NOT use a seed mix with wetting agents for starting vegetables and do not add wetting agents to your vegetable garden soil.
Make Your Own Seed Mix
It is not usually recommended to use garden soil for seed starting; it may contain disease spores that cause damping off or other problems. However, biodynamic gardeners do use a mix of their best top soil and well-aged compost.
Traditional home-made seed mix recipes consist mainly of peat moss, compost and sand, often with additional worm-castings or minerals.
My own adaptation is:
- 4 parts buffered coir
- 2 parts Alaska Humisoil
- 1 part washed sand
- Dash of SuperStart for Plants and/or Marine Mineral Magic
Put through a 1/4″ screen and mix well in a 20 gallon tote. I always experience fast germination, no diseases and exceptional seedling growth. Try it for yourself! ________________________________________