Alyssum is a flowering plant that carpets the ground in beautiful blooms. Gardeners love it because it proliferates and can also be used to fill out any cramped or sparse areas in the garden. But how far does alyssum spread?
Alyssum typically spreads up to a width of approximately 10 inches (25 cm), although it can spread out more. This characteristic is why it’s renowned as a flowering plant that provides good ground cover. Its plant seeds also spread quickly in terms of their flowering.
In this article, I’ll explore why and how alyssum spreads. I’ll also advise on how to make your alyssum bushy and the best places in your garden to plant it.
How Far Can You Expect Your Alyssum To Spread?
Alyssum plants are known for having what’s known as a mounding habit. Mounding means the plants grow bushy and round, providing a dense appearance. Even though they have shallow fibrous roots, alyssum plants can grow up to between four and 10 inches in height (10-25 cm) and up to between 10 and 48 inches (25-122 cm) in width.
Depending on the plant variety, their branches sometimes trail up to 36 inches (90 cm) in length, as Garden Design reports.
Since alyssum grows low to the ground, it works well as ground cover. This attribute is also because it spreads its branches over the soil, creating a mat-like effect.
Alyssum spreads sideways, which is why it’s such a great flowering plant for various spots in the garden. But, it doesn’t spread so much that it’s not suitable for growing in pots. You can also trim alyssum to ensure you maintain its bushy appearance and encourage it to grow.
Different Alyssum Varieties and How They Spread
The way your alyssum will grow depends on its variety. If it’s an older variety, it will be cold-hardy and drought-tolerant but produce flowers during fall and spring while experiencing a bit of a lull during the summer months.
By comparison, modern varieties of alyssum produce more extensive, vigorous plants and tend to flower throughout the growing season. However, these alyssum plants don’t reseed.
There are variations in the spreading habit of different alyssum plants. Here’s a rundown of some of the alyssum plants with the best spread.
- Royal Carpet. As its name suggests, this alyssum plant works beautifully as a ground cover because it grows in purple flowers and reaches a maximum height of between six and eight inches (15-20 cm). It, therefore, boasts significant spreading growth.
- Carpet of Snow. This white-flowering plant grows to between six and 12 inches (15-30.5 cm) in height and width.
- Oriental Nights. This beautiful purple alyssum variety grows between 4 and 6 inches (10-15 cm). The flowers are small, making this a popular variety for use in pots and balconies. It also spreads slower than other plant varieties.
- Tiny Tim. This alyssum is a dwarf variety, which only grows up to three inches (8 cm)! It’s great for the garden or home as it blooms throughout the summer. Since it’s low-growing, it’s ideal for rock gardens.
- Wonderland Copper. This variety grows to around four inches (10 cm) in height and can spread up to 10 inches (25 cm), so it’s one of the best alyssum varieties for sparse areas in the garden.
- Snow Princess. If you’re looking for a bushy alyssum variety, this one is worth adding to your garden. It’s dense and vigorous while having a long bloom cycle. It’s a mounding spreading plant with small white flowers and blooms over a long time.
How Quickly Does Alyssum Spread?
Alyssum is known for its spreading ability because of its dense appearance, but its seeds are also spreaders. Alyssum seedlings can spread quickly. After planting, they take up to 10 weeks to bloom, so you won’t have to wait a long time to see gorgeous flowers appearing on your alyssum plants.
An essential factor contributing to how alyssum seeds spread is that the plant releases seeds when it has spent its flowers. These seeds shake out onto the ground below the plant, enabling the plants to grow the following season without requiring help.
These seeds can also be carried to other areas of your garden by the wind, where they will start to grow, so you might find them sprouting up in places you never expected to see alyssum!
I’ve covered more facts about alyssum reseeding itself in another blog post. Check it out to learn more: Does Alyssum Reseed Itself? What You Need to Know
How To Increase the Spread of Your Alyssum Plant
Even though alyssum plants are generally thick and have lots of flowers and foliage, sometimes they can become leggy, such as if they don’t receive enough sunlight. Trimming your alyssum plants will help them continue to be dense and encourage more blooms to appear on the plants.
Trimming alyssum plants is when you lightly remove their spent flowers and leggy stems. By removing old stems and dead flowers, you encourage the plant to grow healthier ones so that it will flourish.
An excellent tip to follow when trimming your plants is to cut them back by half their height. When you prune back to the healthy foliage of the plant, this boosts its flowering growth, as SFGate reports.
You can cut back by a few inches (approximately 7-11 cm or 3-5 in) if the ends of the plant look a bit ragged or if you can see that its stems have become brown. This method will reveal new green growth on the plant that will sprout fresh flowers.
Can You Plant Alyssum Flowers Close Together?
It’s always recommended to space your flowering plants. Alyssum generally needs a distance between six and eight inches (15-20 cm) from other flowering plants. However, these plants don’t usually become invasive when they grow and spread unless the climate is hot.
They don’t overcrowd other plants that you plant them next to—but rather creep around plants in a way that looks beautiful and doesn’t cause stress to them. Growing alyssum plants close to each other will create a bushy or blanket-like effect, which is excellent for covering sparse areas of your garden.
Alyssum plants look their best when you group them. When they bloom, their leaves aren’t prominent, so they’ll have a sea of colorful flowers on display.
Will Alyssum Spread in Pots?
You can grow alyssum in pots and keep them indoors, as long as you’ve placed the containers in a sunny home area. Alyssum requires plenty of natural light every day. Don’t worry about the alyssum plants spreading—although they might trail over the edge of the pot or basket; this is visually appealing!
Ensure that your pots are approximately 14 inches (36 cm) deep to accommodate the plants’ fibrous roots. These roots move horizontally and cannot penetrate deeply into the soil, so they don’t require deep soil.
Your pots should be porous to ensure proper drainage, considering that alyssum plants don’t want to sit in water. Unglazed terracotta pots are beneficial because they remove moisture from the potting medium effectively.
You can put multiple plants in the same large pot. They will bunch up together and produce a beautiful bouquet of blooms.
Why Your Alyssum Won’t Spread
An alyssum plant that battles to grow and spread needs alterations to its care. The plant could be suffering from problems such as the following.
- Your plant may suffer damage from high temperatures. Although alyssum plants perform well in sunny conditions, hot summer days can cause them to wilt. Be sure to give the plants enough moisture during this time. While you should give your plants an inch (2.5 cm) of water weekly, you should increase this when the weather’s hot and dry.
- Overwatering that’s caused root problems. Alyssum flowers don’t want to sit in water. This excessive moisture can cause them to experience root rot, which can be fatal. If you can see symptoms of root problems, such as slowed growth, cut back the plants and give them some time to recover. Check out my article to help your alyssum rebloom when you cut it back: Will Alyssum Rebloom if It’s Cut Back?
- Alyssum may suffer stress when you transplant them. You should only transplant alyssum plants during the cool evenings or early mornings, such as when moving them from containers to the garden. Give the plants approximately four inches (10 cm) of water after transplanting them. As SFGate reports, continue to give them light moisture for the first few weeks, but let the top inch (2.5 cm) of soil dry before watering.
Final Thoughts
If you’re growing alyssum in your garden or indoors, you might wonder if it spreads a lot. Generally, alyssum stays small in height and width, although it does grow close to the ground. Due to their spread, you can use alyssum plants in a variety of ways, such as:
- Planting them as ground cover
- Planting them in hanging baskets
- Planting them in pots on balconies
- Using them as filler plants, such as in walkways and rock gardens
