The soil drains too slowly for your lilac to tolerate, which is typically the cause of its death. Lilacs need soil that drains properly since waterlogging around the roots of the plant will encourage root rot and Verticillium wilt, which will cause the leaves to drop off and become brown and look to be dying.
The following are the most typical causes of lilac death:
- saturated ground (promotes the conditions for fungal diseases).
- Stress due to drought after planting.
- not enough sunlight in the direct.
- Too much acidic soil (lilacs prefer alkaline soils).
- Too hot and humid a climate.
- Lilac borers are insect larvae that produce fading branches and drooping leaves.
Find out why your lilac is dying and how to save it by reading on.
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Waterlogged Soil Causing Dying Lilac
In their native Balkan peninsula, lilacs naturally flourish in chalky soil and hilly regions. The soil is evenly moist at the roots in this setting, but it also drains properly, preventing water logging at the roots.
The circumstances for fungal disease infections are encouraged if the lilac’s roots are in damp soil because this prevents the roots from absorbing moisture and nutrients, turning the leaves yellow or brown and giving them a withering aspect.
Waterlogged soil also deprives roots of oxygen, interfering with their ability to breathe and preventing them from absorbing nutrition, which causes the lilac to wither and die.
Clay soils that drain too slowly or naturally bog low lying regions of the garden are the usual causes of saturated soil, both of which can lead to a withering lilac shrub.
Compared to most shrubs, lilacs are more susceptible to waterlogged or slow-draining soils.
The shrub can be preserved, though, if the environmental factors are changed before fungal diseases such root rot or vertical wilt begin to manifest.
How to Protect It:
The key to rescuing the shrub is to relocate it to more hospitable drainage conditions that mirror the well-draining surroundings of the lilac’s natural habitat.
To achieve this, I advise urgently relocating your lilac from any soil that drains slowly and has a tendency to become soggy.
Locate a planting place in the garden with better drainage conditions (perhaps on a slope), and amend it with a lot of organic matter (compost, leaf mold, or well-rotted manure), as well as some horticultural grit or sand to help the soil drain better.
There is a significant possibility the lilac can be preserved once it is in well-draining soil that mimics its native conditions if it has only recently been in slow-draining soil.
Toxic root rot and other fungal disease pathogens, on the other hand, are likely to prevent the lilac from absorbing nutrients if it has been in saturated soil for an extended period of time. At this point, the lilac’s branches are probably dying back, and it can be very challenging to save the plant.
Soil is Too Dry (Lilac Dying After Planting)
After planting, lilacs require soil that is regularly moist but also well-draining so that the roots are not sitting in damp dirt.
This is especially crucial after planting a lilac bush because it may take some time for the roots to adapt to the new soil and be able to efficiently absorb water, at which point they are most vulnerable to dying.
Due to their vast roots, mature lilacs (any shrub older than 3 years) are far less likely to experience drought stress, unless there is a drought or the soil is very sandy or stony and drains quickly.
Lilacs that are drought-stressed display wilted, brown or yellow, and falling leaves as symptoms.
How to Protect It:
The best technique to save a lilac under drought stress is to make sure the soil is well-prepared before planting by adding a lot of organic matter.
Compost, leaf mold, or well-rotted manure are examples of materials that help lilacs grow in the best soil conditions because they retain moisture around the roots while also having a porous structure that allows excess water to drain away (preventing root rot and fungal disease). These materials also help mitigate the effects of drought stress.
If your lilac is planted in sandy soil, I advise transplanting it or temporarily easing it out of the ground (gently with a fork) and amending the planting area by adding a lot of compost to keep the soil moist.
Apply a 2 inch layer of mulch around the base of the shrub after giving the lilac a good bath, ideally with a hose.
Mulch makes the soil more lilac-friendly by improving its structure and preserving moisture.
To assist in retaining more moisture, use a mulch made from compost, leaf mold, or well-rotted manure.
Always water deeply, as this helps the roots grow deeply into the ground and establish themselves properly, allowing them to obtain moisture and nutrients and making them more drought-resistant.
Not Enough Sunlight
The most popular varieties of lilacs (Syringa vulgari) planted in gardens worldwide are indigenous to rocky terrain and hilly regions in Southern Europe’s Balkan peninsula, where they can flourish in reasonably open spaces without having to compete with other plants for sunlight.
Lilacs are incredibly cold-hardy, so you don’t need a warm climate to grow them, but for them to grow and bloom, they must be in a spot with full sun for more than six hours each day.
Lilacs can tolerate some partial shade, but they do not thrive in it, growing slowly, producing fewer leaves, and appearing to be dying.
Powdery mildew, a fugal disease that can cause white to gray, powdery areas on the leaves and bark, is also more common when there is less light.
How to Protect It:
If your lilac receives less than six hours of sunlight per day, you might want to:
- moving the tree to a location with at least six hours of sunlight.
- Trim back any nearby bushes or tree limbs that may be shading your lilac plant.
As bright sunlight creates adverse conditions for powdery mildew, this should aid in reviving your lilac and reducing its incidence.
Powdery mildew is not a severe threat to your lilac and it should improve with more light and greater airflow.
(Read why my lilac isn’t blossoming in my article.)
The Soil is too Acidic
The root may not be able to absorb certain nutrients from the soil if the soil is excessively acidic, which results in poor development, yellow or brown leaves, and a withering appearance.
Lilacs can thrive in somewhat acidic soil (pH 6), but it is unlikely that they will flourish in your yard if the soil is substantially more acidic.
If you are unaware of your soil’s pH level and believe that its acidity may be the cause of your demise, I advise speaking with a garden-savvy neighbor since they are likely to be aware of how acidic the soil in your area is.
You might also send a sample of your soil away to be examined or test the soil using a soil test kit from Amazon (which is the most reliable way to accurately of determine the soils pH).
How to Protect It:
Your lilac’s dying appearance is probably caused by, or at least contributed to by, the soil having a pH lower than 6.
In this case, I would advise against growing lilacs in favor of plants that are more suited to the particular pH of your yard (roses, camellias, rhododendrons and azaleas all grow well in acidic soil).
However, you can grow lilacs in an acidic garden by planting them in pots or adding agricultural lime (available from garden centers) to the soil, which will raise the pH from acidic (defined as any number below 7) to either pH neutral (7) or alkaline (any pH value above 7).
Growing a lilac in a container is preferable since it is far simpler to tailor the soil’s features to the needs of the plant than it is to try and change the soil’s properties in your garden. However, soil amendment is a continuous operation.
Warm Temperatures and High Humidity
In the Balkan peninsula’s climate, lilacs are acclimated to cold winters and low humidity (once it is establish lilacs are one of the cold hardiest shrubs).
Too-hot or too-humid climates are incompatible with the lilac’s native environment’s natural conditions.
Humidity makes it easier for fugal infections to spread, and it also makes the leaves wilt and the branches die back.
Because they need a time of cold-induced dormancy to create blossoms and are best grown in USDA zones 3–7, lilacs frequently do not flower when they are grown in locations with moderate Winters.
It is recommended to select other plants that are more suited to your area if you live in a hot region with mild winters and high levels of humidity because it is less likely that your lilac will flower or develop into a healthy shrub.
Lilac Borers- Dying Lilac
Lilac borers are a variety of moths that bore into the lilac, generally in the lower bracing, and leave little entrance holes and sawdust as proof of their attack. Lilacs are sometimes damaged by powdery mildew, which is typically not significant.
Lilac borers cause the lilac’s branches to break off and its leaves to wilt, giving the plant a dead appearance.
Lilac borers can be extremely challenging to eradicate once they become established.
Pruning older branches will lessen the impact of lilac borers because older, somewhat twisted branches with more cracks will provide the larvae more opportunities to attack.
How to Protect It:
Use a lindane spray, an insecticide for burrowing larvae, to prevent lilac borers, which also harm ash trees and privet.
Although lindane spray is a fairly specific product that may not be offered at every garden center, it is still possible to purchase it online.
Healthy lilacs that thrive in favorable environments (enough moisture, full sun, etc.) are less resistant to insect attack, therefore a combination of proper lilac care methods, removing the afflicted branches, and lindane spray can address the issue to help revive your lilac are all important.