Alyssum: Growing The Colorful Carpet Flower

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Alyssum plants have been grown for ages. In Spain in the 1500s, you’d find sweet alyssum bordering edible gardens or growing wild on Mediterranean beaches. Alyssum flowers are not only beautiful, but they also attract many of the beneficial pests that help you grow a garden.

A short-lived perennial, alyssum has been cultivated long enough for the development of heat and drought-tolerant varieties. These small flowers self-seed, and can be biennial in temperate climates. Because alyssum doesn’t get very tall, it’s an excellent way to border a square foot garden or create a barrier between rows.

Alyssum, with its tiny flowers, is a vigorous spreader. There are many different cultivars in many different shades and colors. Alyssum garden zones will have lavender, pink, yellow, and white flowers blooming. Plant white snow crystals, or try a pink variety that blooms in spring and fall, like royal carpet. Whether you choose snow white or pink, you won’t have to search far; seedlings are in every nursery.

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Quick Care Guide

Common Name	Alyssum, sweet alyssum, sweet alison, carpet flower
Scientific Name	Lobularia maritima (syn. Alyssum maritimum)
Family	Brassicaceae
Height & Spread	2 inches to 12 inches tall, 8 inches to 12 inches wide
Light	Full sun to partial shade
Soil	Slightly acidic, well-draining
Water	1 to 2 inches per week
Pests & Diseases	Botrytis (grey mold), clubroot, cyclamen mite, bagrada bugs

All About Sweet Alyssum

Sweet alyssum was originally cultivated in southern Europe, chiefly in Spain. The first records of sweet alyssum date back to the 1500s. The common cultivar of alyssum, Lobularia maritima was hybridized and developed in the 1800s. It’s no wonder that these white flowers are still incorporated into edible gardens today, as they attract hosts of beneficial insects. They’re also relatively maintenance-free.

Alyssum is known as carpet flower due to its low and wide stature, and its use in bedding. The root of the scientific name, Lobularia maritima comes from the Latin words for ‘seed pod’ and ‘the coast’. The plant has a genus synonym, called Alyssum. Some alyssums are annuals. Some are short-lived and perennial. In optimal climates, this plant is a brief biennial.

A member of the Brassicaceae, or mustard family, alyssum plants have simple grey-green leaves arranged alternately on a central stem. Trichomes cover the leaves. Alyssum’s small fragrant symmetrical flowers have four petals and grow in clusters. Flower colors range anywhere from blue to purple, or red to pink. Most common alyssum plants have white flowers. If you’d like to grow the alyssum of the olden days, search for a white variety.

Sweet alyssum plants are small and herbaceous. They bloom in summer through fall. As flowers bloom and die, seedpods called silicles form. When winter draws near, the pods dry and pop open, spreading seed over the ground. Then in early spring, sweet alyssum returns to bloom again.

Because alyssums don’t reach more than 12 inches in height and 12 inches wide, they are often used to border gardens and separate areas. This bordering is either for design purposes or to attract beneficial insects to an edible garden. They attract hosts of pollinators as well, which boosts pollination for food production.

Some varieties of sweet alyssum are vigorous spreaders and may need to be container gardened. Check your local agricultural extension office to determine the best cultivars for your area. If you’re not sure about the species you picked up at a nearby nursery, grow it in hanging baskets or containers. There are many species adapted to different regions of the world, though, so it shouldn’t be hard to find plants.

Types of Alyssum

There are many alyssum varieties to choose from – more than we can showcase here. Here are a few notables to search for:

Snow crystals: This plant is heat tolerant, with gorgeous white flowers blooming in early spring. The minimum height of snow crystals is 6 inches.
Easter bonnet: This tall plant comes in shades of white, rose, red, and pink. The minimum height of Easter bonnet is 10 inches.
Lavender Sweet Alyssum: This lavender blooming plant flowers twice: in early spring and late fall. It stands about 8 inches tall making it great for hanging baskets and bedding. It’s also great for incorporating purple to lavender flowers in a landscape, and for related applications.
Royal carpet: This plant blooms vibrant purple to lavender flowers twice per year in spring and fall. It’s a low grower. Purple and lavender blooms spread out about 10 inches wide at only 3 inches tall.
Pastel Carpet Sweet Alyssum: This medium-height plant comes in light pastel colors of pink, white, yellow, and rose. The maximum height is 9 inches.
Dwarf Pink Sweet Alyssum: lovely compact beneficial companion plant can be used as a ground cover or border flower to attract bees and ladybugs.

Alyssum by the sea — Alyssum thrives in the mediterranean climate of coastal California. Source: Jaykhuang

Sweet Alyssum Care

Alyssums are easy to care for, and many cultivars today are drought, heat, and frost resistant. Choose the right variety for your region. Let’s discuss the basic requirements for alyssums.

Light & Temperature

Sweet alyssum plants require full sun to partial shade. Give sweet alyssum at least 6 to 8 hours of sunlight. Alyssums are hardy to USDA zones 5 through 9 and handle cold temperatures down to 20 degrees Fahrenheit. Alyssum prefers cooler conditions and generally doesn’t do well starting at 85 degrees. There are frost-resistant varieties that tolerate cold, and some that take hot weather.

To overwinter alyssum, either cut it down in winter, cover it with frost cloth, or take containers inside. For those non-heat resistant varieties, provide a shade cloth in summer.

Water & Humidity

Sweet alyssum plants love moist soil, with at least 1 to 2 inches of water per week. Avoid overwatering alyssum as it’s prone to root and crown rot. When you water sweet alyssum, do so in the morning before the ground has warmed. In hot weather, water sweet alyssum in the morning and at dusk. Dusk provides the most protection for water as your plants have more time to absorb moisture before the sun evaporates it.

Drip irrigation protects sweet alyssum leaves and flowers which take damage from overhead watering. Soaker hoses are also appropriate. Because sweet alyssum is a drought-tolerant plant, avoid giving it too much water. Keep the soil moist but not wet. If it rains consistently for a time, don’t water.

Soil

White alyssum flowers — Both white alyssum flowers like these and the pink ones are beautiful. Source: beautifulcataya

Sweet alyssum prefers slightly acidic, loamy, well-drained soil. It survives in containers easily in potting soil. In the ground, sweet alyssum enjoys basic slightly amended garden soil, but it will do just fine in poor soil if that’s all you have to work with. Alyssum prefers a pH of 6.0 to 7.0, so keep your soil at that range.

Fertilizer

Lobularia maritima growing in the ground doesn’t need fertilizer in prepared soils but does better with slow-release granular fertilizer at planting time. In poor soil and containers, provide a water-soluble fertilizer once per month. For ground cover, provide annual fertilizer. Use a 20-20-20 balanced formula for this.

Propagation

All alyssum plants spread vigorously and re-seed annually. However, they do not propagate by division well and are prone to transplant shock.

To propagate from seed, gather seed pods from your annual flowers. Put them in a paper bag, and wait for them to pop. Then sow the seeds over a seed starting mix indoors, directly in a container, or in your garden after the danger of frost has passed, 6 to 8 weeks before the last frost.

Indoors, provide a heating mat for the starting trays and a humidity dome to trap in heat and moisture. Sweet alyssum seeds germinate in temperatures between 50 and 70 degrees. In about one to two weeks you’ll have sweet alyssum sprouts.

After your seeds sprout, thin them to about 6 inches apart. As they come to seedling status, divide them and move them into their permanent homes in a container or your garden 12 inches apart. Do not move them outdoors until the danger of frost has passed. While fully grown alyssum enjoys cooler to cold weather, seedlings cannot withstand extremes such as frost.

When sowing sweet alyssum seed outdoors, they’ll germinate in early spring. Sow seeds as you would indoors. After you sow and they germinate, thin plants to 6 inches, and finally to 12 inches apart.

Ant on alyssum — An ant wanders across the alyssum flowers. Source: TJ Gehling

Pruning

Sweet alyssum flowers benefit from a little pruning. To promote extensive flowers, pinch off the first bloom or two. This gives them the start they need to attract beneficial insects to your edible garden.

After sweet alyssum (Lobularia maritima) flowers bloom and die, deadhead them to promote more flowers. Some carpet flower varieties set flowers very quickly and bloom multiple times in a season. If you have a lot of sweet alyssum flowers, shear them to one-third their size. Then, alyssum flowers will come back stronger in your garden next season.

Sweet alyssum appreciates consistent harvesting. Herbaceous plants that have no interaction with humans don’t have long life cycles. Head to your garden regularly to interact with this plant and give yourself some free herbs for a salad.

Alyssum plants appreciate being cut and mulched in preparation for snow and frost. Mulch traps in warmth and protects alyssum roots through snow and ice from the first to last frost. Although it’s not necessary, as they’ll return in spring, you can cut them down and compost them just before the first frost. This goes for in-ground plants and plants in containers too.

Troubleshooting

While sweet alyssum is maintenance-free, there are tasks to carry out as you care for this mustard family member. Give them what they need, and you’ll see why they have a vigorous reputation.

Growing Problems

If you haven’t planted alyssum in well-drained soil, it could wilt. This goes especially for when the weather is hot. Other than poor drainage, alyssum doesn’t have any problems.

Sweet alyssum is sometimes called carpet flower. Source: Hobo Matt

Pests

Since alyssum plants are beneficial insect attractants, not many insects can take them down. But the pesky cyclamen mite does damage to these plants and their blooms. Cyclamen mites are tiny and hard to detect until the flowering stage. They feed on the sap in flowers and leaves, curling them as they go along.

Prune off damaged areas of your plants where tiny mites have fed. Then,, spray plants with neem oil or horticultural oil to kill off any eggs there. If necessary, treat with insecticidal soap. Search your garden for these signs and catch them quickly, and you’re all good. Your plants will keep flowering throughout the season.

Plants in cool climates are susceptible to bagrada bugs, a form of shield beetle or true bug that sucks sap from the blooms and leaves of annuals. You’ll find them hanging around the undersides of your flowering plants laying tiny eggs. Search the leaves regularly and remove the eggs quickly. Flick bagrada bugs into warm soapy water. In intense infestations, remove the entire plant. Early detection is essential for this pest.

Diseases

Grey mold, caused by the fungus Botrytis cinerea, causes a grey, moldy-looking substance to form on fragrant blooms. It’s most common in cool, damp climates. Remove parts of the plant that have been damaged. If necessary, apply a spray fungicide every two to three weeks.

Clubroot is caused by a fungus that affects plants related to the cabbage family. It can remain in the planting media for up to 18 years. Swollen roots make water and nutrient uptake difficult for infected plants. Cultural methods of control are best employed here. Sanitize tools, replace container planting medium annually, and practice crop rotation. Remove infected plants and allow fields to lie fallow. Solarize the planting medium in areas where the infection was present.