When to plant - Late fall when the soil is cool (around 65o or less) - seeds need a cold period (stratification), or if you don’t want to wait, put seeds in moist (not damp) potting soil in a bag and put in the vegetable crisper drawer of the fridge for 2-3 weeks Snapdragons can also be grown indoors but need well regulated temperatures between 60-70ºF
How to plant - Since they need light to germinate, snapdragon seeds are best scattered over an area and lightly pressed into the soil. If planting in late fall for a spring showing, add compost or fall leaves over the area and keep the area watered through winter (1x/week unless there is rain).
Since snapdragon seeds are very small, they are easily mixed with wildflower mixes and broadcasted over your growing area. If you do want to place individual seeds, or transplant seedlings, make sure that they are 6-12” apart in a well-draining area. It’s a good idea to have drip irrigation in place for snapdragons, as they can be vulnerable to rust, rot, and mildew, all which can occur if there is not proper spacing for airflow between plants, watering from overhead, overwatering, and lack of evaporation (ie, watering at night). If you do notice any signs of disease, it is best to remove this to prevent spreading the disease to other plants. Depending on severity, this could be a few leaves, up to the entire plant (it’s also NOT recommended to compost any diseased plant parts that you have, as these fungi can remain in soil for years to spread to other plants - instead, burn or throw them in the regular garbage).
Once you see sprouts, wait until the plants have 6 leaves before pinching the tip of the stem - this will encourage a bushier plant and more flowers. Also, once flowers start to show, it’s always a good practice to remove dead flower heads (aka dead-heading) to encourage more blooms.
Snapdragons do well as a year-round plant if kept in shade for summer and brought inside for winter (we had snapdragon blooms all year because they were kept next to a heater in the shed). If growing snapdragons in a container, just be mindful of spacing (you can only fit so many in a pot) and watering, as potted plants can dry out more quickly. Snapdragons do not require fertilization, but adding a bloom promoting fertilizer (one with a higher Phosphorous amount) will promote blooming. Nitrogen is good for initially growing a plant, but if added later can cause the plant to grow more foliage than blooms.