The lavender plant will not thrive when it is planted directly in clay soil. Clay soil is prone to retaining excessive water, which can cause root rot. However, it is possible to grow lavender on clay soil provided that you make significant changes to the soil prior to planting by adding gravel to dramatically improve the drainage and structure of the soil.
Clay soils are also difficult for lavender to grow in the following ways:
- Clay soils are rich in nutrients. The lavender is specially adapted for cultivating in low quality, low-nutrient sandy soils of the Mediterranean region of Europe. The soils with high fertility encourage growth of foliage but at the expense of flowers and give the lavender a sloppy and messy appearance.
- Clay soils are prone to compaction and may bake hard under constant sunshine, making it difficult the lavender root to grow.
- Clay soils are generally acidic, whereas lavenders can tolerate moderate acidity (pH 6.5) however, they favor alkaline soils that have pH 7.5.
There are still a few excellent options to grow lavender in clay soils. Here’s how to do it:
- Add clay to the soil by using the aggregate (grit or gravel) to enhance the texture and maintain the proper fertility level.
- Make raised beds and apply amended soil.
- Pots of lavender plants
How to Amend Clay Soils for Lavender Growing
Building Sand is often suggested for amending soil to support lavender cultivation because it mimics the conditions of sandy soils in the lavender’s original Mediterranean habitat.
But clay soils are susceptible to compaction, and consequently, sand is not capable of retaining the porous, well-draining soil structure in clay soils because it is too thin. I’ve seen an area of a garden that was heavy clay was amended by sand, and after a while the soil became thick and had a nearly impermeable texture reminiscent of cement.
However, gravel is far superior in preserving solid foundation in clay soils for longer periods of time. The massive particles bind with each other in a manner that creates larger air pockets within the soil that let water infiltrate and roots to grow into the soil. This is perfect to amend clay.
If your garden is composed of clay that is particularly hard and therefore is remarkably slow to drain, the larger the area that you modify around the lavender , the more efficient.
In other cases, water may accumulate at the point where the amended soil meets the clay. Make sure to select a higher part of your garden to grow the lavender (as it naturally has better drainage) than a lower area that will drain more slowly.
The best advice is to avoid trying to work or dig in heavy clay soil when it’s wet because it will be extremely slippery that it will stick to shoes and shovel instead of digging in a clean manner. This can be very annoying!
1. To amend your soil, it is necessary to excavate the clay area to that is 18 inches in width and twelve inches thick, as it will be able to accommodate the entire lavender plant species once they are fully mature.
2. Get rid of the clay soil, or distribute it elsewhere within the gardens.
3. Replace the clay by mixing a mix made of compost from the garden (or a soil mixture) and gravel in an approximate ratio of 30 percent gravel to 70% compost.
4. Be sure that the gravel and compost is evenly distributed throughout the amended area of soil. This can be done with a spade , but I prefer using a trowel to ensure that each ingredient is evenly distributed.
5. Place your lavender inside the holes, then backfill with sand and compost. The lavender should be firmly planted in the hole using your fingers to provide the plant with some stability , but don’t go into the hole with your heels as it will cause soil to compact and make it more difficult for roots to grow.
6. The lavender should be given a bath that will help reduce the shock of transplants.
For more details on the planting, watering and care for your newly planted lavender, check out the following article What to do when you transplant Lavender.
Alternatives for Lavender Growing in Clay Gardens
One way to prevent the issues caused due to clay is either make a raised bed for lavender, or grow lavender in pots.
Both are extremely suitable for the cultivation of lavender due to:
- Raised beds and pots are an excellent method to lift lavenders out of damp soil and improve drainage.
- It is possible to precisely add the correct proportions of sand/gravel (approx 30 percent) as well as compost (approx 70 percent) to recreate the lavender’s preferential conditions in their Mediterranean habitat (in terms of drainage and soil fertility) without digging out and take away large quantities of clay.
- The pots may be brought indoors in the winter months to avoid damage from frost. (French, Spanish, Italian and other varieties that are not English lavender species aren’t frost-tolerant. The only exception is those English varieties are frost and cold resistant.).
Do I need to include Mulch in addition to Lavender in clay soils?
The most effective kind of lavender mulch in clay soils is materials like wood bark, limestone or white gravel. Organic matter such as leaf mould or compost will retain excessive water and could cause root rot, whereas wood bark or gravel allow water to drain out of the soil, thereby reducing the growth of weeds.
Another benefit of limestone or white gravel is that its white color reflect light efficiently back onto the plant, allowing for more sunshine and warmth around the plant and creates an environment that is microclimate. This is a trick I received from commercial lavender cultivators in California to boost the lavender scent as well as oil production.
Limestone can contribute to soil’s alkalinity as time passes. This is an effective method to maintain the proper soil pH to support lavender (pH 6.5between pH 7.5) in the case of natural acidic soils.
If conditions aren’t favorable then you could opt for raised beds, or pots for growing lavender. The lavender plant also requires full sunshine, moderate to low fertility, good drainage , and frequent watering, which is difficult to achieve in clay soil, but it’s very simple to attain using raised beds or pots.
Check out the article How to Plant Lavenders inside Pots to learn everything you must be aware of when it comes to caring for potted lavenders.
The cultivation of lavender in pots requires much less expertise and considerably less effort than creating raised beds, but raised beds are an affordable and efficient solution to grow plants in clay soils.
Check out this video to learn the simplest and cheapest raised bed instruction:
- Clay soils hold too much water to support the growth of lavender. Lavenders like well-drained soil that doesn’t hold on to the moisture.
- In order to grow lavenders in gardens that have clay soil, you’ll need to dig a hole 18 inches in width as well as 12 inches in depth. Then fill it with a 70 percent compost and 30 percent gravel mix prior to planting the lavender in order to create the ideal drainage and moderate to low fertility requirements that lavenders need.
- Always use grit or gravel instead of sand to improve soil structure while amending clay soils.
- Avoid digging clay in damp conditions because the clay could become slick and will stick to your spade. Make sure to wait for a dry day to do this instead.
- The cultivation of lavender in pots is an easier option that offers better conditions for lavender cultivation than making clay soils and amending them.