Last Updated on September 16, 2022 by Plant Mom Care
Antirrhinum is a flowering genus from the Plantaginaceae family. It is commonly called snapdragons, while their botanical name, Antirrhinum majus (“like a snout”) describes the flowers as resembling the face of a dragon, even opening and closing its “mouth” when squeezed or when insect pollinators such as bumblebees open the “jaws” to collect pollen.
They are indigenous to Europe, North America, and North Africa they are widely grown as ornamental flowering plants in temperate and tropical zones as annuals in gardens, flower boxes, and patio containers and used in cut flower arrangements.
These popular short-lived perennials have lance-like leaves that grow in spirals around the stems, the bright flowers bloom abundantly in cool weather with deeply saturated colors of almost all colors of the spectrum and start from the bottom of the stems and move up, creating long periods of flowering. While these plants usually slow down and stop flowering in the heat of summer, they will keep blooming until autumn if they are kept watered.
These plants come in several varieties and sizes and are usually classified according to their heights – dwarf is 6–8 inches, the medium is 15–30 inches, and tall 30–48 inches. Breeders have been experimenting with these plants for several years, creating creeping and trailing varieties.
They are rather slow-growers when started from seeds, so they are usually purchased as nursery seedlings, although they can be easily grown from seeds indoors several weeks before winter ends.
They usually never flower as vigorously as do in their first year when grown as perennials. However, if you’re lucky, seed pods might form in the first year and they might even self-seed in your garden.
Snapdragons Light Requirements
These plants grow and bloom most abundantly under the full sun as well as partial shade. Once the weather becomes warm or hot, they might stop flowering altogether. Growing them in partially shaded conditions and regular watering will help them through summer and they will probably flower again in fall.
They need ample watering, keep the seedlings well-watered in well-drained soil for their first few weeks. Once they get established, the plants will need watering approximately 1-2 times per week. Water near the soil of the plant and don’t water them overhead to keep them healthy since they are prone to rotting.
Average indoor humidity of around 40% is relatively suitable for these plants. If indoor air is too dry, increase humidity by keeping a humidity tray or humidifier nearby.
These tender perennials thrive in cool or moderate temperatures between 60-75°F. they grow better with night-time temperatures around 40°F. They are usually cultivated as flowering annuals in the cooler seasons of spring and autumn and can survive cold weather.
These plants prefer rich soil with a neutral pH range that also drains well. While they are short-lived plants and not heavy feeders, adding organic compost will help them stay healthy and flourish.
They don’t require repotting as they don’t live very long. However, purchased or germinated seedlings are best repotted into 10-inch large containers.
These plants can be purchased as nursery seedlings and are easy to propagate from seeds, but they can also be propagated from stem cuttings.
Cut off a 2-inch portion of the stem just under a leaf node from a healthy plant, remove lower leaves and dip the end in rooting powder or liquid. Plant the cutting in seed starter soil or regular potting soil when the root system develops and new shoots appear, continue growing them near a bright window or under artificial lights. Transplant outdoors when spring begins.
In milder winters, the seeds can be simply tossed into prepared garden beds in late autumn or before winter ends. However, as they are rather slow-growing, start the seeds indoors 6 or more weeks before the end of winter.
Use a regular seed starter mix or regular soil and just press the seeds on the surface of the growing medium. Place the tray directly under bright lights that are just a couple of inches above the tray as the seeds need light for germinating. The lights must be kept on daily for 16 hours, slowly raising the lights higher when the seedlings start growing.
When seedlings are 3-4 inches high and have about six leaves, cut off the tops of the seedlings to encourage bushiness and branching. They have to be hardened off for a minimum of 10 days before they can be moved to the garden in two weeks before spring begins. Plant the seedlings 18-24 inches away from each other.
Once they are established in the garden, they can withstand very cold temperatures, add pine or straw mulch, and water them well during cold spells to make the plants last for a long time and survive until the cold has passed.
Fertilize the plants when they first start flowering using a well-balanced fertilizer. Water the plant thoroughly to prevent nitrogen burn and help the roots to freely access the fertilizer.
Pinching the stem tips of younger plants will make them grow bushier and thicker. Deadheading spent flowers will extend the flowering season, until late autumn or early winter. These plants can bloom all through the season but they usually flower best in the cool temperatures of spring and fall. In slightly warmer climates, they will sometimes flower throughout the winter.
They can be affected by ethylene gas so removing old flowers and growing them away from ripening fruits or vegetables will help them flower longer. When these plants grow in shady spots, they can get leggy, particularly with taller varieties who fall over when they get top-heavy. Protect the plants with supports that will prevent this.
Snapdragons Flowers Common Problems
Bacterial leaf spots first emerge as small translucent spots with a wide yellow edge that slowly enlarges and becomes angular or circular with a red center. It generally thrives in cool temperatures and can also infect and damage flowers. Remove infected plants and avoid wetting the leaves.
Botrytis causes a grey mold on leaves, stems, flowers, and buds. It usually thrives under cool and wet weather conditions. Remove infected foliage, don’t water the plants at night, and avoid wetting the plant when watering. The plants should have sufficient space between each other for air to circulate. Treat the plants with a suitable fungicide.
Powdery Mildew infects leaves particularly under humid conditions. The leaves develop a powdery white or grey surface and might start curling. Sufficient air circulation with proper plant spacing and pruning is necessary. Use a suitable fungicide to treat the plants.
Aphids spread diseases when they draw sap from leaves and deposit a sticky residue that attracts ants. They can be sprayed off or treated with insecticidal soap.
Cyclamen mites can damage the plants by attacking the foliage. They can reproduce rapidly in hot, arid weather and are difficult to detect. Plants and flowers will become stunted and distorted and the plants might not flower. Remove severely infected plants and don’t wet the foliage when watering. Treat the plants with a good insecticide.
Spider Mites suck the sap and remove chlorophyll and also inject toxins that create white spots on leaves and make foliage turn yellow, dry, and speckled. They reproduce fast and usually appear in arid conditions. Use insecticidal soap to eliminate them.