Starting Native Plants From Seed – Part 1
By Carrington Lauzon, Owner eARTh Revival & Pollinate Collingwood Director
Propagating native plants can seem intimidating at first, but with the proper information and germination requirements met, seeds will have a high yield of growth. Let’s get into some of the science and seed sowing tips below, followed by some common seed treatments required before planting.
The Science of Seed Germination:
The seeds of native plant species each have their own timetable for germination. A built-in physical and chemical dormancy protects them from germinating until conditions are favourable for the seedlings’ survival, usually in spring. Some seeds have a hard outer coat or waxy layer that keeps water out of the seed. This physical dormancy is overcome in nature in several ways, which include; abrasion from soil, freezing, and thawing, digestion by soil microorganisms, passing through the digestive system of animals, and fire. A chemical dormancy is broken when the seed is subjected to one or more of the following, changing its physiological structure; spending a period of time in cold, spending a period of time in cold and moist, being in the presence of light for a period of time and being in the absence of light for a period of time.
Most Ontario native plants that have chemical dormancy will lose their dormancy in nature by spending the winter in the ground cold and moist.
Seed Sowing Tips
Until you are ready to plant or apply pre-sowing treatment, seeds should be stored in a cool, dry place and protected against rodents.
Sow seeds shallowly. Surface sow or sow no deeper than the width of the seed and keep the soil moist but not too wet.
If seeds are very small, you may choose to use a spray bottle to ensure the seeds don’t get displaced by large water droplets.
Clearly label and date the seeds when applying the pre-treatment method.
The germination time of seeds varies, it can take a few days up to a few weeks. Be patient if the seeds don’t germinate right away.
The average frost-free date for South Georgian Bay is May 11th.
For indoor germination: seeds may take a few weeks to germinate and require some maturation before the seedlings can be planted outside. Plan for around 2 months of growing time (germination and maturation), plus add the required pre-treatment time if seeds need stratification.
For outdoor germination: seeds will germinate when the weather and time is right.
Types of Seed Treatments
It’s possible to replicate a natural cycle that causes dormant seeds to germinate by pre-treating the seeds before you plant them. Below are some common pre-treatment methods, the germination codes denoted by a letter are often found on your seed envelopes. You may need to use one or more to get a particular species to germinate.
(A) NO PRE-TREATMENT NECESSARY other than cold, dry storage (also called cold-dry stratification).
(B) SEEDS NEED SCARIFICATION: rub between sandpaper to remove some of the seed coat
(C) STRATIFICATION NEEDED: seeds germinated after pre-treatment of cold-moist stratification. Approximate number of days is in parentheses (i.e. C(30) = 30 days of cold, moist conditions needed) *see Germination Code C stratification recommendations below
(D) SURFACE SOW: seeds are very small and need light to germinate
(E) DOUBLE DORMANCY: Seeds need a warm, moist period followed by a cold, moist period: Mix seeds with sterile medium, place mixture in a sealed plastic bag, and store in a warm (26°C) place for 60– 90 days. Then place in the refrigerator (1-3°C) for 60–90 days before sowing. Or, sow outdoors in early spring and allow one full year for germination.
(F) BEST PLANTED OUTDOORS IN FALL: sow seeds in prepared garden beds or labeled pots in November/December