Alyssum is a small and pretty, easy to grow summer flowering hardy annual that goes by several common names: sweet alyssum or Alison because of its strong, sweet scent and 'carpet of snow' for its masses of tiny white blooms. There are pink and purple-flowered varieties, as well as white, and the flowers are often produced in such profusion that the slender lance-shaped green leaves are barely visible.
The botanical name of alyssum is Lobularia maritima. As the second name suggests, this plant originates from seaside environments, from the Mediterranean and Canary Islands, so it grows very well in coastal areas. It's also a useful bedding plant for border edges, banks and pots. Alyssum plants are small, compact, and slightly spreading in habit, growing to a maximum of 10cm high and 15cm wide. Alyssum flowers are very attractive to pollinating and beneficial insects so it makes a good edging plant to sow around vegetable beds to entice insects to pollinate flowers and help control pests.
How to grow alyssum
Either sow seed direct where alyssum is to flower, sow in modular trays under cover, or buy trays of ready-grown alyssum in spring. Plant out in spring or early summer in well-drained soil and full sun or light shade. At the end of the season once plants have faded or died, pull up and put in the compost bin.
Alyssum: jump links
Where to grow alyssum
As long as the ground is free-draining and doesn’t remain damp, alyssum will grow in any reasonable garden soil. Full sun gives the best flowers although light shade still gives good results. Grow at border edges, in pots and window boxes, on banks, rockeries, or at the edges of vegetable beds.
How to grow alyssum from seed
To sow seed where alyssum is to flower, take out shallow drills and water the ground thoroughly before sowing, then cover with 0.5cm of soil. Thinning the resulting seedlings to 15cm apart will produce larger and sturdier individual plants.
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Sow alyssum under cover in autumn or early to mid-spring: an unheated greenhouse, porch or cold frame is fine, as alyssum is a hardy annual and tolerates a little frost. Sowing in warmth will produce earlier flowers. Use modular seed tray inserts, fill with multi-purpose compost, firm lightly and water well before sowing several seeds to each cell. Cover lightly with 0.5cm of compost. Thin seedlings to one per cell.
How to plant alyssum
Plants that have been raised under cover should be hardened off (acclimatised to the outside) before planting out in mid to late spring. Space plants or thin seedlings to 15cm apart.
Caring for alyssum
Alyssum needs little maintenance once established. After planting, water well to settle the soil around the roots and then water to keep the soil moist for several weeks until plants are established. Thereafter, plants growing in pots will need regular watering while those growing in the ground should only require an occasional thorough watering during dry spells.
Growing alyssum: problem solving
Slugs can eat the young seedlings: protect with an environmentally friendly bait or barrier or start seedlings in trays and plant out when the young plants are large enough to withstand some slug damage.
Downy mildew can occur during spells of wet weather as a whitish or white, purple-tinged coating on the leaves. Ensure alyssum is planted in well-drained soil and at the recommended spacings so there’s plenty of air movement around the plants.