lavender root rot – Gardener Report

Lavenders are low-maintenance plants that live up to 15 years with the right care. All lavenders originate in the Mediterranean region of Europe and are adapted to a specific set of conditions. To revive lavender you have to replicate some of the conditions of their native environment in your garden, in particular the soil conditions. If your lavender looks worse for wear there are several ways to revive it, but first, you will have to diagnose what is causing the lavender to look unwell and in need of saving. Identify why the Lavender needs to be revived The most common reasons lavender needs reviving are: Root rot as a result of overly moist conditions Lavender that is leggy and perhaps has yellow leaves (soil fertility too high) Woody growth that does not support many blooms (a consequence of not pruning lavender every year) Lack of sunshine. Lavenders need full sun and will not grow well in the shade. Lavender planted in the wrong type of pot or container. (Pots need to be 16 inches across and have drainage holes in the base. Keep reading for how to solve these problems so that your lavender returns to full health and blooms the following year... Root Rot (Lavender Turning Brown and Drying Out) Symptoms. The lavender has a wilting or drooping appearance and the foliage is turning brown or yellow. Causes. Watering too frequently, slow draining soil, high humidity, planted too close together, or organic material around the plant (such as mulch or leaves). All lavenders originate in the dry, sandy regions of the Mediterranean coast in Southern Europe. Therefore lavenders require infrequent watering, fast-draining soil with plenty of sunshine, and some airflow between the foliage to grow successfully. Lavenders are drought-resistant plants that thrive in dry environments, which makes them very susceptible to root rot from overwatering and poor drainage from soils that retain too much moisture. Established lavenders only need to be watered once every two weeks in the growing season and they do not require water in the winter. (For more information take a look at my article on how often to water lavenders). Revive Lavenders with Root Rot If the lavender is showing the symptoms of root rot then the first thing you will need to do is to scale back the watering schedule and if the plant is in a pot or container, shelter it from rainfall. Remove any organic material, such as dead leaves, which may have accumulated around the lavender as these materials retain moisture around the lavender and promote the conditions that lead to root rot. Carefully remove the lavender out of the ground with a fork (as a fork is less likely to cut through roots than a spade) and inspect the roots. If there are any soft, rotting roots then snip off the infected roots with a sterilized pair of pruners. Replant the lavender in a new location in full sun with new soil. Amend the soil before replanting with sand or gravel to improve drainage. Read my article for details on how much sand to add and the optimal soil mix. Ideally replant the lavender into a pot with around 30% horticultural grit or sand and 70% potting soil, to replicate the well-draining soil conditions of their native Mediterranean environment. Watch this quick guide to creating the optimal potting mix for lavenders to improve drainage and reduce the risk of root rot: Guide to creating the optimal potting soil for lavenders. If the lavender is replanted in fresh, well-draining soil and you refrain from watering for at least two weeks it will give the lavender the best chance to revive over the next few weeks. In gardens with slow-draining soil (such as clay) replanting the lavender elsewhere in the garden will be ineffective as it is likely to still suffer from root rot if water does not drain quickly after watering and rainfall. In this case, your best option is to transfer the lavender to a pot, container, or raised bed. In a pot, you can control the soil mix much easier than in your garden border and therefore tailor the soil to the lavender preference. (Read my article to learn the best practices for how to transplant lavender and avoid transplant shock). Well draining soil amended with sand or gravel will replicate the lavender native soil conditions and prevent root rot. It is important to remember that lavenders need full sun to flower their best which also increases soil evaporation and contributes to the dry conditions that lavender needs to thrive. Lavenders also need to be planted 2-3 feet away from each other to allow for airflow which again contributes to keeping the plant dry and less likely to develop root rot. Follow these steps and your lavender should begin to revive and show signs of recovery after 3 weeks. Lavenders that are Leggy and Have Yellow Foliage Symptoms. Leggy growth, few flowers, and foliage may turn yellow. Causes. Soil that is high in nitrogen. Using too much fertilizer. Lack of Pruning in the Spring. Lavender natural soil preference is for soils with low to medium fertility. In their native environment, lavenders grow in sandy or gravelly soils. Lavenders are specially adapted to these seemingly harsh conditions. If lavenders are planted in soil that has a high organic content or is high in nutrients, then the lavender will grow leggy and produce fewer flowers which is contrary to the aim of gardeners! Lavenders do not need feeding and supplementing the soil with fertilizer will often turn the foliage of the lavender from green to yellow. Yellow leaves are a sign that there is too much nitrogen in the soil and the plant will be more susceptible to disease. How to Revive Leggy Lavender with Yellow Foliage If you are adding fertilizer to lavender, you should stop immediately. Remove lavenders from rich garden soils and transplant them to either a pot or amend the garden soil with sand or gravel and plant somewhere else in the planting border. Prune back the leggy growth of the lavender either in early Spring or late Fall, but only cut the top third of the flexible growth. Do not cut back to the woody base as it does not rejuvenate very easily. Follow the best practices of caring for lavenders and be patient as it may take some time to fully revive. Amending the soil with sand or gravel is important as this will balance out the fertility of the soil and recreate the low to medium soil fertility that lavenders require. Sand or gravel do not contribute much nutrients to the soil and do not retain nutrients to any great extent. By volume, there should be around 30% sand or gravel and 70% compost when planting lavender in pots or amended garden borders. For more explanation, I recommend that you read my article on the optimal soil mix for lavenders. It sounds counterintuitive but lavenders flower more in lower to medium fertility soils as these are the specific conditions to which they have adapted! Once the lavender has settled into its new home then it may take a season and a good prune to fully revive from its leggy growth and yellow foliage. Woody growth Symptoms. Woody lavender looks untidy, produces fewer flowers and it is more prone to splitting as the wood is relatively vulnerable compared to the newer flexible growth. Causes. All lavenders turn progressively woody. Pruning the lavender every year will slow the formation of woody growth from the base. All lavenders turn woody over the course of their life span. The challenge for gardeners is to slow down the woody growth as much as possible. A well-maintained English lavender can live up to 15 years, although French lavenders only last 4-5 years. (Read my article for more tips on how to increase lavender longevity). Pruning every year is absolutely essential to increasing their longevity as it reduces the rate at which the wood forms each year. How to Revive Woody Lavender https://www.youtube.com/watch?v=cEDwFrB-IX8 Of all the reasons that lavenders may not be at their best, woody lavender is the most difficult to revive. The only way to revive woody lavender is to prune it back, but do not prune into the woody growth. The wood at the base of the lavender is unproductive and will not support any new growth. Lavender only flowers on new seasons growth, so cutting into the woody will prevent it from flowering and potentially kill the plant. Instead cut the top third of the green flexible growth (rather than the brittle woody growth) and prune the lavender into a mound shape as much as possible as this will help to resist weather and prepare for Winter. The best time to prune lavender is in the early Spring (March/April) or late fall (September/October) which is either before or after the flowering season. (watch this helpful YouTube video for more about pruning lavender): https://www.youtube.com/watch?v=9daVr8cFYgY&t=11s To be honest, aside from pruning, there is not much you can do for woody lavender and you may have to simply pull up the plant and replace it with a new lavender. A cost-effective alternative is to take cuttings from the lavender for propagation. Propagating lavender is reasonably easy and can be done without hormone root powder. The best time for taking cuttings is in the early spring. Watch this YouTube video for a clear, visual explanation of propagation from cuttings, or read my step-by-step article for all the best practices for propagating lavender from cuttings. https://www.youtube.com/watch?v=ayF_tjmofaI&t Revive Dying Lavenders in a Pot or Container The most common reasons for potted or container lavenders that look unhealthy and in need of revival are: The pot is not big enough for the roots or for insulation There are no drainage holes in the base of the pot or the use of a drip tray underneath. Ideally, pots should measure 16 inches across with a similar depth. A pot this size has the capacity for enough soil to insulate the roots from cold weather and to contain the right soil mix of sand or a porous texture and good drainage. Small pots can limit the growth of your lavender. Lavender soil needs to have a porous structure so that water drains through the soil and away from the roots quickly and so that there is enough oxygen in the soil for root respiration. Always plant lavender in a 16-inch pot even if it is a smaller variety such as 'Hidcote superior' or 'Munstead' to keep the plant healthy and blooming each year. English Lavender blooming in a terracotta pot. All lavender pots or containers should have drainage holes in the base so water does not pool around roots. A common mistake is to use a drip tray underneath to catch the water so it does not go over a patio or indoor area. This will have the effect of keeping the soil moist and will promote the conditions that lead to root rot. Lavenders do not need watering often (if at all once established) so I would recommend that you move the lavender pot onto a lawn or somewhere similar for 30 minutes after watering so that the water does not trickle over the patio or indoor area. For the full guide, read my article on choosing the best pot for lavender. Revive Lavenders in the Shade (Lavender Needs Full Sun) All lavender species require full sun to grow to their full potential and produce the strongest blooms, oils, and fragrances. The less sun a lavender receives the less it will flower. Lavenders that see less the 6 hours of sunlight during the growing season (Spring and Summer) will likely have stunted growth and die. The only way to revive lavender that has been in the shade is to transfer it to a pot and place it in the sun as quickly as possible. Lavenders require sun all year round, including during the winter dormancy so plant the lavender in a nice open space that is not under a tree canopy or any other shade. Lavender may revive if it is moved into the sun in time, however, there is no guarantee. Otherwise, you should follow the best care practices for lavender to ensure it has a chance to recover. Reviving Lavender After Winter Not all lavenders will survive winter outdoors in climates that experience frost and freezing temperatures. Only English lavenders and Hybrid lavenders are cold-hardy and will tolerate snow, ice, and cold temperatures. French lavenders are more delicate and will die if exposed to freezing temperatures over winter. Therefore French and Spanish lavenders will have to be grown in pots and brought indoors for winter protection in cold climates. Frost-damaged lavenders are difficult to revive and it is likely you will have to replace them. However, bear in mind that lavenders are dormant over winter and therefore you should wait till the early Spring to see if there are any signs of new growth and any chance of the lavender reviving. For the best practices read my article on caring for lavender over winter. I also have a specific article on caring for French lavenders which require more care and attention over winter than other lavenders. Is your lavender plant wilting? I received a question in the comments of this article from Rosemarie: "Please help me …i live at the beach with alot of wind and my lavender in full sun and wilting. Can i cut out the wilting part now in the Spring?Thank youRosemarie" So we've talked in this article about how our lavenders love dry condtions and full sun, and they don't mind some wind, but all three in excess c an cause some wilting as in Rosmarie's case! My advice to her was to cut out any dying part of the lavender, but avoid cutting back into woody growth as lavender doesn't typucally grow back from hard wood. To alleviate the wilting my advice was to mitigate some of the wind and even provide some shade in the afternoon if it is wilting (when the day is at its hottest). You can do this easily if the lavender is potted, but if its planted i'd consider using a wind break like you see at the beach to help buffer excess winds whilst the leavender gets sestablished. You can read my full reply to Rosemarie in the comments and if you have any specific questions of your own please leave a comment and I'll happily reply!! Key Takeaways: The most common reason for dying lavender is because of root rot due to overwatering. Lavenders are drought-resistant plants that need the soil to dry out between bouts of watering. If the soil is too damp the lavender starts to droop, turn brown, dry out, and die back. To revive dying lavender, recreate the conditions of its native Mediterranean environment by planting lavender in well-draining gritty soil, locate the lavender in full sun, and only water the lavender when the soil has dried out. Leggy growth is often a consequence of the lavender being planted into soil that is too high in nutrients or because of added fertilizer (Lavenders prefer low to medium-fertility soils). Transplanting the lavender into soil replicates the low to medium fertility of the lavender's native Mediterranean, sandy soils. The lavender should revive by the next growth season. Lavender needs to be pruned back once a year in the Spring or Fall to prevent it from turning woody. Prune the top third of the lavender's flexible growth back, but do not prune the woody growth. Lavender that has turned too woody can be propagated from cuttings for more plants or may have to be replaced. Choose the appropriate lavender for your climate. English lavender is cold-hardy whereas French lavender will die in cold winters.