Lavenders are perennial sub shrubs that are great for forming aromatic decorative hedges, plants and borders around the garden. However you may be concerned that they will spread in your garden in the same way other herbs are known to...\n\n\n\nLavenders can spread in terms of vegetative growth, with the largest varieties reaching 36-40 inches (90 - 100 cm). Lavenders can spread by seed dispersal but the rate of germination is low and almost negligible. You can prevent lavender from spreading by trimming off seed bearing flower heads in late summer.\n\n\n\nLavenders do not spread by division, self propagation or any other method apart from seeds dispersed from pods developed in their spent flower heads in late summer. (Although they are easily propagated with cuttings by gardeners).\n\n\n\nThe seeds require very specific conditions to germinate therefore, lavenders will not pop up unexpectedly in random parts of your garden in the same way that other herbs are known to do.\n\n\n\nDifferent varieties of lavender grow to different sizes and the amount of growth is influenced by how well they are cared for and pruned each year. \n\n\n\nKeep reading to learn how much lavenders spread and how to avoid seeds spreading... \n\n\n\nHow Much do Lavenders Spread?\n\n\n\nHow much a lavender will spread in terms of vegetation growth and size will vary significantly by variety and whether they are receiving optimal care, primarily in terms of sunlight, soil condition and regular pruning.\n\n\n\nGenerally speaking, lavenders have been cultivated into three different categories, dwarf, semi dwarf and giant lavenders...\n\n\n\nType of LavenderPopular Varieties How far Lavenders SpreadDwarf Lavenders'Hidcote Superior', 'Munstead', 'L. stoechas' etc.Dwarf varieties will grow to 16 inches x 18 inches (40 cm x 45 cm) and rarely exceed 24 inches in height and width when fully grown. These compact lavenders grow well indoors as house plants and outdoors as decorative boarders. Semi Dwarf Lavenders'Hidcote', 'Pink Perfume', 'Loddon Blue' ect.Semi dwarf or medium tend to spread to 20-24 in (50-60 cm) in height and width at full maturity. Giant Lavenders'Hidcote Giant', 'Alba', 'Mailette' etc.Giant lavenders can grow as large as 36-40 inches (90 - 100 cm) in height and width at the height of summer, if they are planted in optimal growing conditions. Giant varieties are commonly grown by commercial lavender growers.\n\n\n\nAll Lavenders grow to roughly the to the same height as their width. This of course depends on how well they plant is cared for and how much space it has to grow.\n\n\n\nThe amount of sunlight in particular is a big determining factor to size, health and the strength of the blooms each summer and pruning is necessary to extend the life of the lavender and maintain shape.\n\n\n\nLavenders that are not pruned regularly will become leggy, produce less blooms and be more vulnerable to weather damage.\n\n\n\n(If you lavender is not blooming read my article for the solution).\n\n\n\nLavenders require at least 6 hours of sun per day but the more sun they receive the better for blooms.\n\n\n\nOf course, how far each lavender spreads in terms of growth should determine how far apart you should plant your lavenders.\n\n\n\nLavenders grow best with around 2-3 feet of distance from one another. Lavenders should be spaced appropriately so that they enjoy a breeze (which helps reduce fungal disease) and so that they receive enough light throughout the day without shadowing one another.\n\n\n\nSpacing them apart also means there is less competition between plants in terms of space for their root systems, access to water and nutrients.\n\n\n\nIt is best practice to prune your lavenders into a mound shape once in the early spring and again at the end of summer to cut back spent flower stems. This will help maintain an attractive shape, limit the weaker woody growth and stop lavenders from spreading or becoming misshapen. \n\n\n\nHow to Avoid Lavenders Spreading by Seed\n\n\n\nLavenders can spread by foliage growth (as with all plants) and seed dispersal in the late summer.\n\n\n\nLavender plants do not spread by self propagation, or any other mechanism (however they are reasonable easy to propagate with some planning). They can be physically divided, but this has a much lower success rate then taking cuttings to propagate.\n\n\n\nLavenders will develop seeds in seed pods that emerge from the spent flower heads in the late summer. If you haven't trimmed off the spent flower heads through the season then you will be able to hear the seeds rattling inside. \n\n\n\nThis is a big advantage in terms of controlling the spread of lavender as all the seeds are contained in one seed pod and therefore much easier to control just by deadheading the flowers before the seeds fully develop.\n\n\n\nEven if you let the lavender go to seed it is very unlikely to self set. Herbs like oregano are notorious for self seeding but lavender seeds very rarely germinate from self seeding. In all my experience as a commercial gardener I haven't seen lavender spread in this way, so it is not something you should worry about in your garden.\n\n\n\nThe process for gardeners to grow lavenders from seed requires several steps such as a period of cold followed by warm soil temperatures of around 75\u00ba to 80\u00baF (23.9\u00ba to 26.7\u00baC) and ideally they need to be heated from underneath the soil in their trays.\n\n\n\nIt is unlikely that the series of specific steps to grow lavenders from seed in the correct sequence would happen naturally in your garden.\n\n\n\nThere is also the fact that lavender hybrids are often seed sterile and the only way to produce more plants is through taking cuttings for propagation.\n\n\n\nControlling lavenders seed dispersal is very easy and rarely a problem for gardeners in all climates.\n\n\n\nKey Takeaways\n\n\n\nLavenders only spread by vegetation growth or by seed dispersal.Generally lavenders will grow as wide as they are tall. The maximum vegetative spread of lavender is around 36-40 inches (90 - 100 cm) for species such as 'Hidcote Giant'.The germination rate of lavender seeds is very low compared with other herbs and self set lavender is rarely is 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 is influenced by the amount of sunlight they receive, the amount of space they are given and how well they are cared for.Pruning lavenders to a nice round mound shape in the spring and a light prune just before winter will keep the lavender healthy, stop it from spreading and becoming leggy.