While lavender has a reputation for being a hardy, easy to care for plant, it can easily be killed if you don’t know the right conditions to give it.
If your lavender is on its last leg, here are some ways you can try to bring it back to life.
And if none of those work, we’ll talk about one additional method you can use to turn your old, dying plant into several new, healthy ones.
Problem: Too Much Water
The most common thing that kills lavender plants is that they’re being provided too much water.
This can either be because you’re watering them too much, that you live in an area with too much rain, or that you have a heavy clay soil that is retaining water for a long time after they’re watered. (Because of how slow draining clay is.)
This problems, whether individual or combined, can lead to root rot – which can kill your plant pretty quickly.
To fix this issue, you need to cut back on how much water your plants are getting. If you’re watering your plants, you should reduce waterings to once every two weeks or less.
Otherwise, you need to look at the condition of your soil. If you have clay soil, or if you notice the soil around your lavender plants holding onto moisture for a long time after they’re watered, you may need to ammend the soil.
Lavender grows best in unamended sand, so if you have clay soil you may need to mix in compost to help it drain more quickly. This works best if you’re on a slope or if you have a french drain system near your plants to help draw water away from them, because the soil below what you ammended will often still drain slowly.
Otherwise, it may be best to try to dig your plants up and plant them in a raised bed with coarse sand that’s at least 10″ deep. While you have your plants out of the ground, inspect for brown, mushy roots that may need to be pruned off.
The same thing goes if you’re growing them in containers. Remove them from the container, get off as much of the old potting soil as possible, and repot with a mix of 70% well draining potting soil and 30% perlite.
Problem: Not Enough Sun
Lavender plants need at least 8 hours of sun per day to truly be healthy. If you’ve planted them in part or full shade, they’ll be scraggly and leggy and won’t bloom as much as they’re supposed to.
If this is the issue, the only way to fix it is to dig up your plants and move them to somewhere that they’ll be able to get more sun. (Unless they’re shaded by a tree or bush that you can prune to give them more sun.)
If you’re moving them, you’ll want to read my guide on how to grow lavender and take all of the suggestions into consideration when selecting a new site.
Problem: Yellow Leaves, Lack of Blooms, Plant Growing Sideways
If your plant is starting to yellow, has stopped flowering, looks a bit leggy, and is growing sideways, the problem may be that you’re growing in soil that has too high of a nitrogen content. It may also lose its smell.
The cause of this is usually that you spread fertilizer, manure, or other soil amendments with too much nitrogen (the first number in the 0-0-0 on the bag).
Lavender is used to growing in sandy soils with very little nutrients in them, so when you provide them fertilizer or other plant foods, they often stop growing correctly.
The solution to this is to remove the fertilizer if possible (if you spread granular fertilizer) or otherwise just wait it out and prune the plant back into shape once its exhausted the extra nitrogen you gave it and returned to its normal growth habit.
The only fertilizer you should give it is an inch of compost as a top dressing at the start of the spring growing season before it flowers.
Alternatively, make sure your lavender isn’t getting shaded out, as mentioned in the previous point.
Problem: Lack of Pruning
One of the few maintenance activities that lavender absolutely needs to be healthy is pruning. A properly pruned English lavender should live 15 years. If you neglect pruning, however, it will become a woody mess that probably has to be replaced after 5.
Once or twice per year, you should cut your lavender plants back by half. Don’t cut it down to where there is no green growth left on the stems, but do cut it back significantly. This will keep your plant looking happy and healthy for years to come.
If you’ve neglected this, there may not be much you can do. You can try to give it some remedial pruning to get it back into shape, but the parts that have already become woody are just going to stay like that for the life of the plant.
If it’s too far gone, you may have to replace it – or go to the last item on this list where I discuss how to grow new lavender plants from your current one. (No seeds required.)
Problem: Your Lavender isn’t Cold Hardy
If you’re growing a type of lavender plant that isn’t cold hardy down to the zone that you’re growing it in, it may be killed during one of the colder days of winter.
If this happens, you can wait for spring to see if it comes back (and just prune off the dead parts when you see what’s still alive), but most likely the plant is going to have to be replaced. When getting a new plant to replace it, look for a variety that is cold hardy.
Hidcote Superior is said to be the most cold hardy variety of lavender, surviving temperatures down to -20F, so that may be an option to go for if English lavender will grow in your area.
There are a few common diseases that lavender plants get, including Alfalfa Mosaic Virus and Tobacco Mosaic Virus. Less common is Lavender Shab Disease.
The mosaic viruses cause yellowing, especially on the bottoms of the leaves, in patches, leaving blotches of green. I don’t have a picture of it on lavender, but here’s what it looks like on zucchini plants. This will give you an idea of what you’re looking for.
These don’t outright kill the plant, but they will reduce its productivity and can be easily spread to other plants. (Even ones that aren’t lavender.)
You can still use the blooms in anything you’d normally use them for, though, because the virus isn’t harmful to humans or animals.
Shab, on the other hand, is a fungal disease that will cause the plant to wilt and will kill it pretty quickly.
What’s common between these diseases is that they can’t be cured, and you should dig the plants up and burn them to prevent further spread of the disease.
If you think your lavender plant has a disease, take a cutting from it down to your local extension office for positive identification. Remember to sanitize your shears with bleach afterwards to prevent further spread.
Some of the common insect pests for lavender plants include spittlebugs, whiteflies, and aphids.
Aphids you’re probably aware of. These are tiny bugs that like to hang out on the stems of plants near new growth and drink the sap from the plants. They can spread disease (such as the mosaic viruses) and generally make a nuisance out of themselves.
Generally, aphids are said not to like lavender – meaning they won’t stay and feed if they have a choice otherwise, but they can still spread disease even if they decide they don’t like the plant and move on afterwards.
Aphids are generally taken care of by a thorough soaking with a spray made from neem oil.
Spittlebugs – also called frog-hoppers – leave little nests that look like bubbles made out of spit on the stems of your plants and – like aphids – drink the sap from your plants. This can stunt the growth of the plant and spread disease.
To take care of spittlebugs, blast them with the garden hose, and then spray them with neem oil.
Whiteflies are annoying little white bugs that flutter around your plants and land on the bottom of your leaves to (you guessed it) drink your plant’s sap. As with the other two I’ve discussed, they can spread disease and harm your lavender.
Spray down your plant with neem oil, paying close attention to the bottoms of leaves.
What to Do If Your Plant Can’t Be Saved
If your plant can’t be saved, it’s time to think about propagation. This will let you create new, healthy lavender plants out of your old, dying one.
First, a word of warning: This requires some healthy shoots to be left on your plant. If your plant is completely dead or is afflicted with a disease, this method won’t work.
If your plant still has good growth left on it, take some small pruning snips and cut off sections that have at least three leaf nodes left on them. Strip the leaves from the lower two nodes and dip them in rooting powder.
Get a seed tray with sterile seed growing mix, and place the cuttings into the cells in the tray. Give them a good misting, and put them in a humidity dome with a grow light for a few weeks. After 2-3 weeks, they should start growing roots.
From this point, you can start potting them up into small pots and growing them like new plants. I have a more in depth guide – with pictures – on how to do this in my beginners guide to growing lavender.
There are quite a few different things that can kill your lavender plant, and the key to knowing whether you can save it or need to replace it is identifying what’s wrong with the plant to begin with.
If your lavender plant can’t be saved, you should give serious thought to whether or not you’re growing the correct variety of lavender for your area. For hot, humid, rainy areas, lavender phenomenal is a good variety that will thrive where others die. For cold areas, on the other hand, hidcote superior is a good choice for a lavender that will survive some of the coldest winters.
Good luck with trying to save your plants.