Common bay tree problems and how to fix them
Although they are generally low-maintenance, there are a few common bay tree problems to get to grips with if you’re planting one or two of these evergreens in your garden.
Bay tree problems are generally not too complicated – their easy care regime is one of the reasons they make one of the best trees to grow in pots. However, if you’ve spotted yellowing leaves, odd markings, loss of vigour, or other unexpected symptoms on your tree, then you’ll likely want to get to the cause.
Below, we’ve rounded up top advice on how to identify and treat common issues that occur with these structural, aromatic trees, so you can continue to enjoy them in your back garden.
1. Scale insects
If you’ve spotted odd blemishes on the leaves of your bay tree, they have turned yellow and started to drop off, or have become coated in a sticky-like substance, scale insects may be the problem.
As John Negus, a renowned horticulturalist and gardening journalist explains, these are tiny, armadillo-shaped creatures that weaken trees by feeding on sap while releasing a sticky, honeydew-like substance.
You can control them with an insecticide that’s safe to use on edible crops. Based on rape seed oil, it clogs the pest’s breathing pores, which kills it. It is recommended for several pests. Alternatively, John suggests spraying the tree with a mild solution of washing-up liquid and water.
Additionally, fertilising the plants with sulfate of potash monthly from mid-spring to early fall is a good idea. Sprinkle it over the root area at 28g per square metre and water it in.
This natural insecticide keeps pesky bugs at bay and is suitable for use on edible plants.
2. Restricted roots
If you have planted your bay tree in a garden planter and it’s looking unhappy, it could be the size of the pot that’s the problem.
Your tree could be distressed because its container is full of roots, so move the tree to a pot that is at least double the existing size. Water the compost to loosen feeding roots clinging to the side of the pot and gently remove the rootball.
Then, in the new pot, add a layer of crocks and nestle the roots into 7cm of soil-based compost mixed with a quarter part, by volume, of grit. Fill with more compost.
Replant the bay at the same depth at which it is growing and water it well. Mulching the top of the compost with slate or grit will help conserve moisture.
3. Bay suckers
Brown, curling leaves on a bay tree can be a sign of bay suckers – a pest resembling fluffy white stars that devours leaf undersides.
“When feeding, this creature causes the plant’s leaves to develop thick, distorted bulges,” explains John Negus. “Luckily, although this is unsightly, it doesn’t do irrevocable damage to the bay.” However, severe infestations can cause leaves to drop prematurely, and shoots to die.
As for controlling it, the best approach is to pick off and bin or burn affected foliage. Clear away fallen leaves and other debris from the base of the plant, too.
You could also use a pesticide, although several applications may be necessary. Remember to use one that’s safe for edible crops if using the leaves for cooking. Ideally, do this during warm sunny days in spring, when the adults cluster on the shoot tips to feed before laying their eggs.
“Alternatively, encourage natural predators such as birds, ladybirds, wasps and ground beetles to frequent your garden,” says John.
4. Leaf spot
Leaf spot is a fungal disease, which, John Negus explains, shows as necrotic gray or brown spots on the leaf.
“The best way to deal with it is through good hygiene and improved growing conditions,” he says.
Start by removing affected leaves and raking up any fallen leaves. Then, feed the plant a balanced fertiliser early in spring to encourage new growth.
This organic fertiliser provides balanced macro and micronutrients, helping to improve soil quality.
5. Winter damage
Bay trees are generally hardy to -5°C, according to the RHS, and can survive even lower temperatures if planted in a sheltered position. Simply wrapping pots in two layers of heavy-duty bubble wrap, covering the compost surface with 7–10cm of chipped bark, and positioning pots close to a south-facing wall is usually enough.
However, it’s not a good idea to prune them during cold weather. Frosts can damage the cut surfaces, resulting in possible dieback. Instead, trimming the trees several times during the growing season is needed, stopping in early autumn.
Harsh winter conditions can also cause the bark to peel and crack, especially on main stems lower down on the plants, says the RHS. Although it may look unsightly, it tends not to be fatal, and generally, bays should recover the following summer. If parts of the plant die, however, simply remove these by cutting back to healthy wood or right down to near soil level.
Bubble wrap might not be the first thing you think of as a gardening essential, but it will protect your bay trees from cold weather.
These bay tree problems may be common, but by keeping an eye out for the above symptoms and following our expert-backed solutions, they’ll be revived in no time.
For more gardening advice, read our guide to box blight or learn about the worst time of year to prune a hedge.
The original version of this article previously appeared on Gardeningetc, a sister website to Homebuilding & Renovating.