Lavenders are native to Mediterranean countries and in order to successfully grow lavenders you must replicate the soil conditions of that region.
Lavenders thrive in sandy, well draining soil with a low to medium level of fertility. Lavenders can grow in mildly acidic soils but prefer to grow in soils that are pH neutral or slightly alkaline. Lavenders grow very well in naturally sandy or chalk soils.
This article will discuss exactly what soil conditions lavenders love and how you can replicate these conditions to grow lavenders that flower well in your garden.
This advice applies to all varieties of lavenders and their hybrids
Lavenders Need Good drainage
Soil that allows for good drainage is the most important factor when growing lavenders.
Lavenders are native to the Mediterranean, where they thrive in full sun with little rainfall and sandy soils that drain very quickly.
You certainly don’t have to live in a Mediterranean climate to grow lavenders but you must replicate the dry sandy soil condition in order for them to grow and flower successfully.
Lavenders in gardens with clay, or any cold wet, slow draining soil will be susceptible to root rot and the lavender will not survive if you do not amend your soil before planting lavender.
If your garden is slow draining or tends to retain a lot of water then you have three options for growing lavenders.
- Grow lavenders in raised beds. By planting lavenders in a raised bed you have complete control of the soil medium that you introduce into the bed and the lavenders will be out of any low lying areas which can collect water naturally.
- Grow lavenders in pots. Lavenders do exceptional well in pots as pots provide dryer conditions and good drainage (as long as there are good sized drainage holes in the base of the pot) and of course you can amend the soil with plenty of sand or grit to further provide the optimal soil drainage conditions.
- Amend the soil in your garden where you are planting lavenders with an even sand (or grit) and soil mixture). You don’t have to be too precise as long as you test that the soil drains quickly after watering before planting the lavender. If water seeps away slowly, you will need to add more sand and grit to the mixture and try again.
Unless you have naturally sandy or rocky soils or are even lucky enough to live in the Mediterranean countries of Spain, France and Italy then you will have to amend the soil with course sand or grit in order to replicate their natural growing conditions.
Coarse builders sand is far better then fine sand and grit is also recommended. These materials will provide the soil with air pockets and the appropriate structure so that water will drain away from the lavender roots nice and quick.
Sand and grit are also low in nutrients which suits you lavender well. High nutrient soil is likely to promote foliage growth and fewer flowers and soil that is high in organic matter will also retain too much water for the lavender to thrive.
Rich soils that contain a high amount of organic material can hold a lot of water which will rot the roots of the lavender and also create humid conditions which does not suit the arid loving lavender.
If you soil is already somewhat fine then adding 1 third sand or girt to two thirds compost will ensure the right level of drainage, however if you have rich soils that drain slowly you will have to use a 50:50 sand or grit to compost mix for best results.
Always do a test before planting the lavender by watering the planting area and observing how fast the water drains away. If the soil drains well and water does not collect then this is the ideal soil condition. If drainage is slow then amend with more grit and try again. This is not an exact science and will require some trial and error.
The Correct Soil pH for Lavenders
Lavenders can grow in mildly acidic soils but prefer soil that is either pH neutral (pH 7) or slight alkaline (up to pH 7.5).
Lavender does particularly well in gardens with chalk soils as chalk allows for good drainage and tends to be slightly alkaline.
If you do not know the pH of your soil then it is very easy to get it tested with a very inexpensive kit on amazon. Testing your soil pH does not require an special knowledge of chemistry and it can ultimately save you a lot of time and money as you know what plants grow favourably in your garden soil.
Most garden soils are around neutral but if you do have acidic soils in your garden you can add some garden lime to it or even some wood ash which will raise the pH of the soil so that it is appropriate for growing lavenders and other plants.
Multipurpose compost with the amendments of grit and sand will be suitable for growing lavenders from the perspective of pH levels so there is no need to worry if you are planting in pots or filling up raised beds.
Soil Nutrients for Lavenders (What you Need to Know)
In terms of soil nutrients lavenders prefer low to medium fertility soils. If the soil is too rich in nutrients then this will promote foliage growth of the lavender to grow and consequently there would be far less flowers.
Lavenders thrive where most plants would struggle and actually reward a gardener who can provide them with the seemingly harsh conditions they require.
A general multipurpose compost will suit lavender just fine and the only amendments you need to make are with sand and grit which will provide the structure and low nutrient content that the lavender need.
I once read advice about adding fertilizer to lavenders which is not something I (or the RHS) would recommend.
Lavenders need low to medium fertility in their soils and fertilizer will only promote excessive foliage growth with less or even no flowers and a high concentration of fertilizer would harm the roots of the plant.
Personally I have never added fertilizer precisely because lavenders prefer nutrient poor soils, I have been growing lavenders, both planted in beds and in pots that give off spectacular fragrance and always produce and abundance of flowers.
Adding fertilizer only contradicts the conditions in which lavenders thrive so provide them with compost and sand and they will have the best chance of producing beautiful, fragrant flowers!
Growing Lavenders in Different Soil Types
It is perfectly possible to grow lavenders in heavy or clay soils as long as you have amended the planting area to a depth of atleast 12 inches and a width of 16 inches.
This is assuming that the area where you intend to plant the lavenders receives full sun (preferably more the 6 hours of direct sun per day).
Clay soils in particularly are not only unfavourable in terms of structure but also in terms of high fertility. With clay its is important to dig out you planting area and replace the soil with at least 50% grit to 50% multi purpose compost.
Grit is more capable of providing air pockets in the soil and maintain its structure in heavy soils compared to just sand. You should always layer the bottom of the planting hole with 2 inches of grit to ensure that water does not simply collect underneath the lavender and cause the roots to rot.
Again its important that you test the soil’s drainage before planting by thoroughly watering the proposed planting area and making sure it drains quickly and adjusting by adding more grit if necessary.
Lavenders are relatively short lived plants and often expire after 4 years so it is important to either propagate lavenders if you intend to extend the life of a lavender hedge.
Conclusion
Key takeaways:
- Lavenders need the soils conditions that emulate their native Mediterranean soils.
- Fast draining, pH neutral or slightly alkaline, low to medium fertility sandy soils are the optimal conditions.
- Lavenders grow well in raised beds, pots and soils amended with sand or grit and multipurpose compost.
- You do not need to add fertilizer to lavenders as this will promote foliage growth and less flowers. Lavenders prefer lower to medium nutrient soils therefore they do not benefit from fertilizers.