lavender not flowering – Gardener Report

Assuming Lavenders are receiving the right care, then all species of lavender flower at some point during the Spring and Summer. If a Lavender has not produced little or no flowers during the growing season then this is a sign that the plant is stressed. The healthier the lavender is the better it will bloom so there are a variety of reasons why lavender can be too stressed to flower: The soil is too fertile for lavender to flower (lavenders require low fertility)Added fertilizer promotes foliage growth at the expense of flowersThe less sun lavenders have the less they will flowerThe lavender is planted in acidic soil (Lavenders require alkaline soil)Over watered lavender will be stressed and is less likely to flowerSoil is draining too slowly causing fungal diseaseThe climate is too humid for lavenders to flowerThe lavender is suffering from transplant shock It is the wrong time of year for flowering Keep reading for more information on why your lavender may not be flowering and if there is anything you can do to ensure flowering in the next season... 1. Fertile Soil Prevents Lavender Flowering The most common reason for lavender not flowering is that the lavender is planted into rich fertile soil. This may sound counter intuitive as most popular cultivated plants thrive in healthy fertile soil. Lavender plants however are adapted to low fertility, sandy or gravelly soils in their native home range of the Mediterranean in Southern Europe. Sand and gravel contribute very little nutrients to the soil, but the provide the ideal soil structure that lavenders require. For lavenders it is far more important to have soil that drains quickly and holds little moisture as they like their roots to be kept somewhat dry between periods of watering. It is in these nutrient poor soils that lavenders produce their best oils, fragrance and flower display. High fertility soils promote lots of foliage growth but that comes at the expense of flowers and will be to the detriment of healthy lavenders. Lavenders in soils with a high nitrogen content will grow leggy with yellow foliage and most likely will produce little or no flowers. To remedy this you have to amend the soil in order to replicate some of the lavenders preferred natural conditions. This is fortunately very simple to do. Gently fork out the lavender plant out of the ground and dig in plenty of sand or gravel so that the soil is approximately 30% sand to 70% soil, but it is better to have too much sand then not enough so be generous. For more information on amending the soil to balance out fertility, follow the steps in my article: How to transplant lavender successfully. The best time to do this is the spring but if your lavender is turning yellow (a sign of excess nitrogen) then this will need to be done more urgently, but avoid transplanting in winter as lavender roots struggle to establish when planted into cold winter soils. If you have amended the soil and other conditions (such as full sun and well drained soil) are in place then the lavender should make a recovery and produce flowers for the next year. 2. Feeding Lavenders will Reduce Flowering This point is very much related to the previous problem of soils that are too fertile. Like all plants lavender does require the nutrients Nitrogen (N), Phosphorous (P) and Potassium (K). The difference is that Lavenders are not heavy feeders and an excess of these nutrients in the form of fertilizer will cause you lavender not to flower. This is again because lavenders actually thrive on relatively neglectful conditions such as watering once every two weeks, blazing sunshine and low nutrient soil as this is the environment they are accustomed to living in, with sandy, alkaline soils of Southern Europe in countries like France, Spain and Italy. Adding fertilizer to lavenders will stimulate lots of leggy foliage growth and deter flowering, which is contrary to the goals of any lavender gardener. The most influential factors that encourage lavenders to produce flowers are sunlight, the right watering schedule, and soil that somewhat resembles that of the lavender natural habitat (which is easy to achieve) and twice yearly pruning, so skip the fertilizer in favor of consistent good care. If you have added fertilizer to your lavender then I would encourage you to remove it from the soil and replant it in a different location as this ground will too fertile for the lavender to flower to its full potential. 3. Not Enough Sunlight to Flower Lavenders need full sun to flower, produce oil and exude its best aroma. The less sun that a lavender receives, the less flowers that will be on display. Lavenders are habituated to the sunny conditions of the Mediterranean where they grow best in full sunshine. Whilst some species of lavender (English Lavenders, Lavandula angustifolia) do not need to the hot conditions of the Mediterranean to grow or display plentiful flowers, they all need as much sun as possible. Lavenders will flower if they receive 6 hours of light per day during the spring and summer (preferably morning sunshine) but the more sun the better for flowering. Any less then 6 hours of direct sunlight per day the lavender will be under significant stress and will not be able to flower, and the lavender will possibly die so move the lavender or transplant the lavender to a pot and place in a sunny location. 4. Lavenders Need the Right Soil pH to Flower Lavenders need to be planted into soil that has a pH of 6.5-7.5. Lavenders can tolerate some mild acidity but prefer to be in slightly alkaline soils. Most garden soils are between pH 6-7 with 6 being acidic and 7 being neutral. So it is possible that your garden soil is a little too much on the acidic side for lavenders to be healthy and produce flowers. Therefore you may have to test the pH and amend the soil with agricultural lime or wood ash (which are alkaline) in order to raise the pH of the soil so that it is suitable for lavender growing. (To measure soil pH easily in your garden, I recommend buying a soil gauge which is easy to sue, does not require technical knowledge and is available for a great price on Amazon!) Soil gauge to measure soil pH in your garden. 5. Over watered Lavenders May not Flower Over watered lavenders will not be able to flower and will likely suffer from the fungal disease root rot. Lavenders only need watering sparingly (once every two weeks during the growing season) and established lavenders will likely attain all the moisture they need from rainfall without additional watering. (For more information, read my article on how often lavender should be watered). 6. Lavenders in Slow Draining Soil can Prevent Blooms Lavenders that are planted in soil that drains too slowly will have the same sort of problems as over watered lavender. If the soil is consistently wet then lavender will either be too stressed to flower and potentially die from the fungal disease root rot. It is essential that lavender is planted into soil that allows excess water to drain away from the roots. Soils that have a high clay content tend to retain water which is unsuitable for lavender growing. If you have clay soil in your garden, read my guide on how to amend and change its structure to grow lavenders. 7. High humidity is Detrimental to Lavender Flowering Lavenders are acclimatized to bright sunlight, low humidity and can tolerate breezy, coastal weather. Lavender does not grow or flower well in humid climates. High humidity can cause fungal disease, turning the foliage brown. This will stress the lavender so that it cannot produce flowers. Transplant Shock can Reduce Flowering Transplant shock from planting or transplanting lavender at the wrong time of year or into less then optimal conditions can also stress the plant. Lavenders are best planted or transplanted in the early spring when the ground has warmed up. Lavenders do not like to be moved or planted in Winter as their roots will struggle to establish in colder, moist soil and may suffer from root rot as a result. Read my article on how to transplant lavender whilst mitigating transplant shock. 9. Not all Lavender Varieties Produce Flowers at the Same Time Assuming the plant is healthy, all lavenders should flower at some point during the spring and summer growing season. English Lavenders (Lavandula angustifolia) are one of the most commonly cultivated garden lavenders and they tend to bloom in the Late Spring to early summer for around four weeks. Typically this is in the last two weeks of June and the first two weeks of July, but this can obviously vary due to inconsistent weather. French (Lavandula dentata) and Spanish (Lavandula stoechas) lavender typically produce flowers for a lot longer, however they are not cold hardy so should be grown in climates with a mild Winter that does experience frost. In the right conditions French and Spanish lavender can flower from Spring to late Summer and into the Fall, particularly if they are deadhead regularly to encourage more flowering. So it may be the case that your particular lavender cultivar is yet to flower or you have missed the window of flowering depending on when you bought the plant. Key Takeaways: The reasons for lavender not flowering are usually because the plant is stressed. Lavenders are adapted to sandy soils of low fertility. If the soil is too rich and nutrient dense then the lavender will grow leggy and produce fewer flowers. Feeding lavenders will also have the same effect, with the lavender foliage turning yellow which is symptomatic of excess nitrogen in the soil.Lavenders planted in overly acidic soil will harm that plant. Lavenders tend to be healthiest and flower the best when they are planted in soils that are slightly alkaline, although they will tolerate some mild acidity (lavender can flower in soils that are between pH 6.5 and 7.5).Lavenders are drought resistant plants that do not need much water and will suffer in soils that drain to slowly. Both these factors can cause lavenders to develop the fungal disease root rot which will likely stop the lavender from flowering.Climates that are too humid will cause the plant to be stressed and increase the susceptibility to fungal disease which will prevent a good flower display.Planting or transplanting your lavender at the wrong time of year, or into conditions that are not optimal could shock the plant which will reduce flowering that year, although the lavender may make a full recovery and flower the following growing season.English lavenders flower in late spring and early summer whereas French and Spanish varieties can flower from spring up until fall, although they are less cold hardy then the English lavenders.