Lavenders are incredibly versatile and aromatic sub shrubs that can be used to create beautiful hedges, plants, and borders in your garden. However, you may have concerns about their spreading tendencies, as is the case with some other herbs. Let’s take a closer look at how lavenders spread and how you can prevent any unwanted growth.
How Lavenders Spread
Lavenders primarily spread through vegetative growth, with larger varieties reaching heights of 36-40 inches (90-100 cm). Although they can also spread through seed dispersal, the germination rate is quite low and almost negligible. You can easily control the spreading of lavenders by simply trimming off the seed-bearing flower heads in late summer.
It’s important to note that lavenders do not spread through division, self-propagation, or any other method apart from seeds dispersed from pods that develop in spent flower heads. However, gardeners can easily propagate lavenders through cuttings.
The specific conditions required for lavender seeds to germinate mean that you won’t find unexpected lavender plants popping up randomly in your garden, unlike some other herbs. Different lavender varieties grow to different sizes, and their growth is influenced by proper care and pruning each year.
How Much Do Lavenders Spread?
The amount of spread lavenders achieve in terms of vegetation growth and size can vary significantly depending on the variety and how well they are cared for. Factors like sunlight, soil condition, and regular pruning play important roles in their growth.
Lavenders are often categorized into three groups: dwarf, semi-dwarf, and giant lavenders. Each variety has its own growth characteristics and spread:
- Dwarf Lavenders: These varieties typically spread to around 16 inches x 18 inches (40 cm x 45 cm), with a height of 24 inches.
- Semi Dwarf Lavenders: These lavenders spread to about 20-24 inches (50-60 cm) in height.
- Giant Lavenders: These larger lavenders can reach heights of 36-40 inches (90-100 cm).
In general, lavenders tend to grow to roughly the same height as their width. However, this can vary depending on how well cared for the plants are and the space they have to grow. The amount of sunlight they receive is particularly crucial for their size, health, and blooming strength. Proper pruning is essential to maintain an attractive shape and ensure healthy growth.
To allow for proper airflow, reduce the risk of fungal diseases, and provide adequate sunlight, it’s recommended to plant lavenders with a distance of 2-3 feet between each plant. This spacing also prevents competition between plants for resources like water and nutrients.
Pruning lavenders into a mound shape in early spring and again at the end of summer helps limit weak woody growth and prevents the plants from spreading or becoming misshapen.
How to Prevent Lavenders from Spreading by Seed
Lavenders can spread through foliage growth, as is the case with all plants, as well as through seed dispersal in late summer. However, lavenders do not spread through self-propagation or any other mechanism. While they can be physically divided, this method has a lower success rate compared to using cuttings for propagation.
Lavenders develop seeds in pods that emerge from spent flower heads in late summer. If you haven’t trimmed off the spent flower heads throughout the season, you may hear the seeds rattling inside. However, controlling the spread of lavender is quite easy since all the seeds are contained in one pod. Simply deadhead the flowers before the seeds fully develop.
Even if you allow the lavender to go to seed, it is highly unlikely that they will self-set and spread. Unlike other herbs like oregano, lavender seeds rarely germinate from self-seeding. As a commercial gardener, I have never seen lavender spread in this way, so it’s not something you should worry about in your garden.
The process of growing lavenders from seed requires specific steps, including a period of cold followed by warm soil temperatures of around 75º to 80ºF (23.9º to 26.7ºC). Additionally, lavender seeds need to be heated from underneath the soil in trays. The natural occurrence of these precise conditions in your garden is unlikely.
It’s also worth noting that lavender hybrids are often seed sterile, making taking cuttings the only reliable means of producing more plants.
Controlling the seed dispersal of lavenders is rarely a problem for gardeners in all climates.
Key Takeaways
To summarize, lavenders spread through vegetative growth or seed dispersal. While lavenders can reach heights of 36-40 inches (90-100 cm), their spread is primarily determined by the variety, care, and pruning. The germination rate of lavender seeds is low compared to other herbs, so self-set lavender is rarely, if ever, a problem in gardens.
To prevent lavender seeds from spreading, simply trim off the flower heads after they have bloomed. The size and spread of lavenders depend on factors such as sunlight, spacing, and care. Pruning lavenders into a round mound shape in spring and lightly pruning them before winter will keep the plants healthy and prevent them from spreading or becoming leggy.
By following these simple guidelines, you can enjoy the beauty and fragrance of lavenders without worrying about their spreading tendencies in your garden.