February is the month gardeners start sowing vegetable, herb, and ornamental seeds to transplant outdoors in spring after the last expected frost date (March 31 in Columbia).
For decades soilless germination mix, aka seed starting mix, comprised of sphagnum peat moss, vermiculite, perlite, and limestone has been the gold standard for home gardeners and professional growers. The soilless peat mix, developed by two Cornell University horticulture professors in the 1960s, changed the greenhouse industry and introduced a new product to gardening consumers. The lightweight artificial soil provided good drainage, was free of weed seeds, reduced disease problems, and made plant care and maintenance much easier.
Check the ingredients in your seed starting mix. Most brands in the U.S. retail market still embrace the Cornell formula with peat being the major component. Canada is the source of the peat found in seed starting substrates sold throughout North America.
However, 21st century horticulturists, environmentalists, and climatologists are sounding an alarm to stop using peat-based mix. Why? What has changed? Peat is harvested from peat bogs, a wetland of soft spongy ground consisting of partially decayed plant matter called peat. Peat bogs are a major global carbon sink, trapping carbon and helping mitigate the effects of climate change. The bogs also help control flooding and provide habitat for native plants and animals. Peat bogs cover three percent of the earth’s land but store 30 percent of the earth’s soil carbon. When bogs are mined for peat, they emit carbon dioxide into the atmosphere, thereby contributing to climate change. Scientists believe the need for carbon sequestration to fight rising temperatures is imperative.
February is seed starting time in South Carolina.
In The United Kingdom, the Wildlife Trusts have called for a ban on peat use in compost by 2025. The Royal Horticultural Society is calling for peat-free gardening. “Bogs not Bags” is their initiative to keep peat in the bogs and not in commercial compost bags. www.rhs.org.uk/advice/peat.
Gardeners can make their own seed starting substrate recipe.
If soilless peat mix is not used, what green options exist to assure success for seed starters? A number of public university horticulture departments across the U.S. are conducting research on new substrates to substitute for peat. At N.C. State University in Raleigh the Horticultural Substrates Laboratory is testing a variety of substrate candidates including a variety of wood fibers, pine bark, rice hulls, and coir.
Several commercial horticulture companies have produced peat-free seed starting mix. Gardener’s Supply in Vermont advertises individual coco coir circular discs for seed starting and Eco-co Coir Seed Starting Mix from coconut husks. Burpee Seed markets an Eco-Friendly Seed Starting Block made from sustainable coconut coir.
While it could take years of research and development to find sustainable substrates to replace peat in commercial mixes, home gardeners can experiment to create their own seed starting recipe with homemade screened compost, leaf mold, vermiculite, and perlite.
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