One of the first flowers to make an appearance in the spring garden is the pansy — and it is one of the last to cease blooming in the fall. Pansies are definitely cool-weather plants, and in fact, they sometimes take a blooming holiday in midsummer during the hottest weather, and that is acceptable because many other plants are in full bloom to take up the slack.
If pansies and violas are to be a decent size for transplanting into the garden in the spring, they must be seeded indoors in March. The seed is not a fast germinator and the plants are rather slow growing, so they must get a good head start. To encourage germination, pansy seed should be pre-chilled in the refrigerator for at least 24 hours before it is planted.
Pansy and viola seeds are best planted in a sterile soilless mix and the seeds should be covered with a light dusting of fine medium just to cover them. The planting medium should be pre-moistened and kept moist during the germination process. The best way to keep the medium moist is to enclose the planted container in a plastic bag, but to ensure that there is no undue buildup of moisture inside the bag, open it periodically to make sure moisture levels are appropriate — if there is too much moisture moulds or fungus diseases might develop.
Pansy seeds are among those that require total darkness to promote germination. Covering the planted container with black plastic or several thicknesses of newspaper will block out the light. They also prefer cool germination temperatures, which is rather uncommon, as we often tend to place germination trays where there is lots of warmth. The best germinating temperatures for pansy and viola seeds is 18 to 20 C. Germination may be uneven and take as long as three weeks although some seeds may germinate within the first two weeks. You may wish to coat the seeds with a fungicide before planting them by adding a bit of fungicide powder to the seed pack and shaking it to coat the seeds with the powder. Of course, take adequate precautions when handling chemicals of any type.
Remove the covering and expose the seedlings to good, strong, indirect light immediately after germination has occurred. Seedlings soon elongate if they do not receive enough light. The best plants will be obtained if the seedlings are grown in a cool environment — the growth will be slower but the plants will be shorter and more compact. Pansy seedlings are prone to damping off so ensure good air circulation and let the soil surface dry out between waterings, and do not keep the medium too wet.
Pansy and viola seedlings are ideal candidates for growing on in an outdoor cold frame where they will get lots of direct sun and not get too leggy. Cool nights will not bother them nor will any spells of cool weather. It is safe to plant them into the outdoor garden in early May, particularly if the plants have been hardened off sufficiently in a cold frame as they will tolerate any late-spring frosts without any adverse effects.
Pansies and violas can be used as annuals, but when doing your fall cleanup, consider leaving the plants in place as they very likely will survive the winter and be one of the first plants to bloom in the garden the following spring.