Antirrhinum is a genus of over 30 species of annual and perennial flowering plants, more commonly known as snapdragons. Though the most popular Antirrhinum species, Antirrhinum majus, is an annual, gardeners can enjoy vibrant snapdragons in their gardens or home landscapes year after year by planting a perennial snapdragon variety such as Antirrhinum braun-blanquetii. With the exception of special winter care, the care for perennial snapdragons is almost identical to the care of their annual counterparts. Perennial snapdragons can be grown successfully in United States Department of Agriculture (USDA) plant hardiness zones 5 through 8.
Plant perennial snapdragons in a full sun location in your garden or home landscape that receives six or more hours of direct sun exposure per day. Choose a location that also provides rich, fertile and well-draining soil, or amend the soil at your planting location by tilling 3 inches of peat moss, well-rotted manure and perlite into the top 8 to 10 inches of soil. For best results, plant your perennial snapdragons at the same level that they were growing in their garden centre container.
Water perennial snapdragons immediately after planting them to eliminate any air pockets trapped beneath the surface of the soil. Continue to water the snapdragons once or twice a week, or as often as necessary, to prevent the surrounding soil from drying out. Apply the irrigation directly to the soil, as wetting the plant's foliage can increase its risk of contracting fungal diseases. Avoid watering perennial snapdragons during the cold winter months, when the plant is dormant and not actively growing.
Fertilise your perennial snapdragons once a month during the spring, summer and fall with a half-strength solution of a balanced, water-soluble flowering plant fertiliser. Follow the application instructions on the fertiliser package to ensure that your snapdragons are receiving the correct amount of nutrients. Note that following a regular fertilisation schedule will help ensure healthy, vigorous plant growth and prolific blooming in your perennial snapdragons.
Deadhead your perennial snapdragons throughout the growing season to encourage your plant to produce additional blossoms. Pinch or snip faded or dead blossoms from your plant, as needed, to extend its blooming period and maintain an attractive appearance.
Cover the surface of the soil around your perennial snapdragons with a 5-inch layer of peat moss, pine straw or similar natural mulch before the first frost to protect your plant from cold winter temperatures. Remove the thick layer of mulch in the early spring, before new plant growth is observed. Prune out any discoloured, diseased, damaged or dead foliage from your snapdragon plant with a pair of sharpened and sterilised pruning shears to promote healthy new growth during the growing season.
Maintain a 2- to 3-inch layer of mulch on the surface of the soil around your perennial snapdragons throughout the growing season to help the plant preserve moisture and discourage the growth of weeds in your flower bed.
Perennial snapdragons are susceptible to damage by common insect pests including aphids and spider mites. If an increase in insect activity is negatively impacting your plant's health, correct the problem with a garden insecticide product.