Growing plants from seed a rewarding experience
Many of us have had success with starting seeds that simply require moisture and warmth to begin the germination process. However, figuring out how to start seeds needing other conditions in order to break dormancy can be a real challenge.
Knowing a bit about the environment a plant naturally grows in can give us clues about what types of dormancy we are dealing with. For example, desert plants wait for a rainy year before they germinate, to give them the best chance of survival. As a result, these seeds need to be soaked for an extended period of time before being planted, to mimic their natural environment.
Most plants native to temperate regions have developed methods to keep their seeds dormant until conditions are favourable for germination and growth (for example, enough moisture, heat or light). These include: a seed coat that doesn’t easily allow water intake; chemicals on or in the seed coat that prevent germination; an undeveloped embryo at the time of dissemination; and an embryo that requires a physiological change to overcome dormancy (usually an extended period of cold). Added to this, some seeds have more than one type of dormancy at play!
It can be interesting to learn about the different types of dormancy and how to overcome them in order for the seeds to germinate within the time frame we are willing to provide. Obviously, we can let nature do its thing by planting seeds and leaving them outside, sometimes for several years, but some of us find it a fun challenge to get the more difficult seeds to germinate on our terms.
For best results, ensure your seeds are viable by selecting good quality, fresh, mature, clean seeds that have been tested for germination. Two excellent sources of seeds that include germination information on their websites and on the individual packages are Gardens North (www.gardensnorth.com; Canada) and Alplains (www. alplains.com; U.S.).
Remember that air is an important part of the germination process, so make sure you provide good aeration within your soil mix, and keep your soil moist, but not waterlogged. Moisture must remain constant once seeds are subjected to water. If seeds dry out after the germination process begins, they will die. Ways to prevent drying out are to cover seed trays in plastic, or to water and/ or mist them on a regular basis. Check every day until you know how often they need watering. I mist every day once I have taken off the plastic, and set reminders for myself. (As a side note, it is easy to forget seedlings that are in the basement.)
Something else you need to know is whether or not to cover the seeds with soil. Some absolutely need to be exposed to light (some Penstemon), others should be covered lightly (most Allium) and others need absolute darkness (some Delphinium).
After exposing seeds to water to begin the germination process, we then have to consider the temperature (s) needed for the rest of the germination period. Fortunately, many plants are happy germinating at room temperature. These include most annuals, most members of the aster family (such as Achillea and Echinacea) and other common garden plants like Campanula, Dianthus, Heuchera, Sempervivum, Veronica, etc.
Others need to be kept cooler (good options are on the floor of an unfinished basement or in an unheated porch in the spring). Many other seeds germinate best when exposed to the natural temperature changes experienced outside over the winter (snow, hard frosts at night with thawing during the day, etc.) Place moist pots outside in a shaded spot and cover with window screen. Make sure they don’t dry out. This method works well for seeds needing cold stratification (for example, Penstemon, Gentian, Thalictrum and more). Gibberellic acid (GA3), available from Gardens North (with excellent instructions for use), will allow you to bypass the cold period.
Some seeds will also do well placed in moist vermiculite, inside a labelled baggie in the refrigerator, for the specified number of weeks (four to 12). Check for germination every couple of weeks and pot up any that have sprouted, and then keep them at room temperature.
Occasionally, plants need to be started warm for four to eight weeks, then placed in a cold environment for another four to eight weeks, and finally returned to the warmth before they will germinate. Many plants that require moist packaging to preserve their viability fall into this category (Corydalis, Hepatica and Aconitum, are a few examples).
The last category we will cover is seeds requiring scarification. These seeds need to be rubbed with sandpaper, or nicked with a sharp knife, to allow water to penetrate the hard seed coat. Almost all plants in the pea family require this method (including Lupine, Baptisia and Lathyrus), as do many tree and shrub seeds.
Knowing the challenges of germinating certain seeds, why would we want to do this instead of growing from cuttings? Generally, seedlings will develop better root systems than cuttings, producing stronger plants that do better than plants bought from a nursery. Growing from seed also contributes to genetic diversity. Most importantly, it gives me such pleasure to be able to say, “I grew that plant from seed!” May you gain great happiness through the challenges and successes of growing the more difficult plants from seed!
It gives me such pleasure to be able to say, ‘I grew that plant from seed!’