A low mat of tiny honey-scented flowers that blooms for months and feeds more beneficial insects per square foot than almost anything else you can sow.
Lobularia maritima · also called Alyssum, Carpet Flower
Windows are counted from the average date of your last spring frost.
The shallow, open flowers are sized for hoverflies and tiny parasitic wasps, the insects that clear aphids from nearby crops. It also works as a living edge that shades bare soil and gives a mild sweet-cabbage garnish.
A little history. A member of the cabbage family despite its look, native to the Mediterranean coast. Its flowers are shallow and open, so short-tongued beneficial insects can reach the nectar.
Press seed onto the surface and barely cover — it needs light. Mist daily so the top quarter-inch never dries. Seedlings emerge in 5–14 days in warm soil.
Sow seeds 0.06 inch (2 mm) deep.
Water twice a week in warm weather; less once established. Water when the top inch of soil feels dry. Aim for about 1 inch per week including rain.
Once at planting; skip further feeding. What to use: a thin layer of compost worked into the top 2 inches.
Shear the whole plant back by a third with scissors when bloom thins in midsummer heat. Water after shearing; new flowers follow in 2–3 weeks.
It's ready when flower clusters are fully open and fragrant, before individual petals brown. Pick in the cool of the morning. Snip whole flower clusters with scissors just below the head, taking no more than a third of the open blooms at a time so the planting keeps feeding insects.
Refrigerate loose in a lidded container lined with a damp paper towel; use within 3 days. Flowers wilt fast at room temperature.
Sow a fresh patch every 4–5 weeks through midsummer if you want unbroken bloom without shearing older plants.
Carnation
Alyssum's tiny open flowers feed hoverflies and lacewings, whose larvae eat the aphids and thrips that cluster on carnation buds. Sow it as a skirt at the front of the carnation row so it does not crowd their stems.
Lettuce
Field trials in lettuce repeatedly show that alyssum strips draw in hoverflies, whose larvae cut aphid numbers in the crop. Plant one alyssum every few feet within or beside the lettuce block.
Broccoli
The nectar suits the tiny parasitic wasps that attack cabbage aphids and caterpillars. Keep alyssum at the bed's edge rather than between plants, since both are cabbage-family and share root diseases.
Bell Pepper
A low border of alyssum under peppers often reduces aphid buildup by keeping hoverflies and lacewings in the bed. It stays short enough not to compete for light.
Cucumber
Sown along the bed edge, the low mat shades bare soil, holds surface moisture, and crowds out weeds while its flowers pull in pollinators that cucumbers need for well-filled fruit.
Strawberry
Alyssum flowers early and long, bringing bees into the patch during strawberry bloom, which helps fruit fill out evenly. Keep it out of the runner zone so it does not tangle with the crowns.
Cabbage
Alyssum is a cabbage-family plant, so it can host clubroot and the same aphids and caterpillars. Grow it as a border rather than interplanted, and do not let it self-sow through beds you rotate cabbage crops into.
Mint
Mint spreads by runners and will simply run over a low alyssum mat within a season. Keep mint in a sunken pot or a separate bed if you want the alyssum to persist.
Fennel
Fennel's roots release compounds that stunt most garden neighbours, and a shallow-rooted seedling like alyssum has little defence. Planted well apart, though, fennel's own flowers feed the same hoverflies and tiny wasps, so both earn a place in the garden.
Easy-going — Sweet Alyssum can grow almost anywhere in the rotation without a strict rest.
The pea and bean family, the cabbage family or the tomato family thrive in this ground next season.
A light feeder that leaves the bed much as it found it, so it fits almost anywhere. It is cabbage-family, so leave a 1-year gap before another cabbage-family crop here; peas or beans, cabbage-family greens, or tomato-family crops all follow well.
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