If the leaves of your lavender plant turn yellow, it’s likely to be a sign of stress caused by excessive fertilizer in soil. The lavender plant requires a low to moderate fertility soil. When nitrogen fertiliser is used or other materials like manure or compost enriched with nitrogen are utilized, the leaves of lavender are likely to turn yellow. The plant is likely to grow less upright and have fewer flowers.
Yellow leaves may also signify the presence of water or that lavender isn’t in an area that has good airflow (lavenders do not like air stagnation) or maybe the soil is acidic.
Lavenders are native to dry Southern Europe, where they thrive in coastal regions with alkaline, medium to low fertility sandy soils that do not hold moisture, and have very little rainfall.
To stop lavender leaves from becoming yellow, it is essential to recreate their natural conditions to ensure they remain healthy and show flowers.
Continue reading to find out the reason your lavender plants have turned yellow and how to correct the issue…
1. Yellow Leaves are due to soil that is rich in nutrients
The yellow leaves are usually an indication it is too heavy in nitrogen. The best lavenders will thrive in with a low-to-medium fertility pot mix. In the event that there’s too high levels of nitrogen in the soil, the lavenders will become yellow and produce less flowers.
If you’ve put in your lavender pots…
- Manure, or
- Enriched compost
…or or something similar, then the soil’s rich in nutrients is in opposition to those conditions of low fertile that lavenders need, which leads to yellow-colored leaves.
Other indicators of stress include less blooms during the summer, and a leggy, untidy growth.
The best solution involves amending the soil prior to planting.
The ideal mixture of soil for the lavender flower is one that drains well (to stop root rot) and has about 1/3 of horticultural sand , or grit , and 2/3 of ordinary pot soil that is available at any garden store that is reputable.
(Read more about my article on how to make the best soil for lavenders to grow in containers and pots).
Sandy soil is a recreation of the conditions in which lavenders thrive in countries such as Spain, France and Portugal.
If you have a medium to low fertility soil mix, lavenders will develop properly, show more flowers, and the foliage will be lush and green with an intense aroma.
It could take a few weeks for lavenders that have yellow leaves to grow back after they are moved to a new potting mix, so you must be patient, but they should be able to be able to recover.
2. Root Rot Because of Over Watering
Lavenders can be affected by a few ailments, but root rot is an issue due to:
- Too often watering
- Slow draining soil
- Pots with no drain holes on the bottom
Potted lavenders require a good soak each two to three weeks. If you’re frequenting your watering, is likely to be overwatering the lavender.
(Read my article on on how often to wash lavender)
Lavenders are drought-resistant, plant that tolerates heat, and prefer to let the soil dry between periods of watering.
A soil that is constantly humid will create the conditions that cause fungal root that causes rot that can cause the lavenders’ leaves yellow or brown and can result in a drooping appearance.
Even if you’re not regularly watering your lavender it could be that the soil is too arid and holds lots of water. It is essential to add a large amount of sand , or even grit in the potting mix prior to planting to ensure proper soil drainage.
If you have a sandy garden, you have significantly less chance of the plant developing root rot, even when the plant is heavily maintained or gets lots of rain.
The best solution is to take all lavender out of the ground, and then cut off the roots that appear like they are rotten and yellow using sterile pruning tools, leaving only normal, healthy roots.
Replant the lavender in a new pots with lots of sand or grit and allow it to dry out over two weeks.
The benefit of growing lavender in pots is the ability to relocate it to a protected area, away from rain to allow the roots and the soil time to dry out.
Within two weeks you can water the lavender every two or three weeks up to the fall (do not water the lavender during winter as it is in an inactive state and will get all the water it needs when left outside).
Lavenders aren’t always able to recover from root rot that is severe however if you take action promptly, there’s a good chance that the plant will grow in a timely manner.
3. Leaves Turning Yellow Because of Fertilizer
This is a common error that many gardeners make. Since lavenders are adapted to low fertility to medium fertility soils, they don’t require any additional fertilizer.
Fertilizing lavenders can have the same effect (if not more) than growing lavenders in fertile soil.
The first indication of stress due to fertilizer addition is the fact that leaves begin to turn yellow and there are fewer flowers in summer, as well as an odor that is less strong and a messy appearance.
After fertilizer has been applied, all you have to do is to change the soil to an abrasive or sandy potter’s mix and then replant the lavender.
If you are amending the soil, you should use horticultural sand or grit since this sand is larger in particle size that can make a more porous soil which allows for better drainage and root oxygenation.
4. Inappropriate Pot for Lavenders
It is possible that lavenders’ leaves may change color as a result of stress if they’re placed in a pot that is not big enough and leaves the plant roots bound.
Plant lavenders in pots that are at least 12-16 inches in diameter even if it’s smaller varieties like Lavandula angustifolia “Hidcote Superior” or Lavandula Stoechas “Anouk”.
The size of the pot is sufficient to ensure that the lavender’s root system is able to grow and that the pot has the capacity to hold soil that has sufficient moisture and access to nutrients.
A bigger pot also means the soil is larger available to protect the roots during Winter.
Check out my article to find out more about selecting the best pot to grow lavenders in..
Another issue to consider is the absence of drainage holes in the base , or the need to use a plate to catch the water that drips out from the bottom or the base.
If the excess water cannot be able to drain easily from the bottom of the pot, then the soil is too wet for the lavender’s roots. This can result in root rot, and the lavender’s leaves turn brown or yellow with a droopy appearance.
5. Soil pH
Lavenders are tolerant of mild soil acidity, but prefer soils that are pH neutral or alkaline , which can range between the pH 6.5 that is acidic, to pH 8, which is alkaline. (Read my article on how to determine the pH of soil specifically for the lavenders).
Lavenders planted in soil that is acidic may struggle to absorb nutrients, which can cause yellow leaves and slow growth.
Do not use the ericaceous (acidic) compost. Instead, grow lavenders in regular pots. By adding a teaspoon of horticultural lime (available at gardens centers or on the internet) or half one cup of wood Ash (both contain alkaline) will ensure that the lavenders ‘ soil mix is in the right range.
Take the lavenders out of the soil immediately if you suspect that acidic soil may be the cause and then plant them in fresh soil, with lime added to ensure that the lavender has the best chance to recover.
(Read my article on on how you can plant lavender in containers and pots).
- A potted lavender that has yellow leaves is typically an indication that there is too high levels of nitrogen in the soil as a result of fertiliser or soil too fertile (Lavenders are attracted to low to medium fertility soils).
- Slow draining and over-watering soils can lead to fungal diseases that causes the leaves of lavender to change color from brown or yellow with a drooping look. The lavender plant is drought-resistant which require only watering often once they are established. Plant lavenders in soil that is sandy to aid drainage.
- It is essential to select the proper pot for lavenders. The lavender that is root bound may be yellow with slow growth, which is a sign of stress. Lavenders require pots that have drainage holes at the base to let excess water drain away and prevents root decay.
- The lavenders prefer alkaline soils, and don’t do very well in soils that are acidic. The leaves of lavender can change color and show slow or slow growth. Plant the flowers in pots using some wood ash or horticultural lime (which can both be alkaline) to make sure the soil is in the right range to grow lavender.
- To ensure healthy lavender plants and to avoid the leaves becoming yellow, you should recreate the conditions of the native lavender habitat in the Mediterranean, that is, sandy soils with frequent irrigation and full sun.