Portuguese laurel: leaf, growth and disease problems (+fixes)

Portuguese laurel hedge foliage
Portuguese laurel foliage

Prunus lusitanica, Portuguese laurel (or Portugal laurel), is a hugely popular hedge plant for good reason. It’s very hardy to winter cold, it grows quickly and vigorously and provides an effective evergreen screen for privacy, as well as wind and noise reduction. Trained as a standalone tree, it makes an attractive and controllable addition to any garden.

Some think it a smarter, easier-to-control alternative to the very popular cherry (aka English or Common) laurel. In fact, gardening legend Monty Don calls it “superior in every way”.

Portuguese laurel problems are chiefly related to drought, which can cause poor growth and excessive leaf yellowing, and to wind exposure. While resistant to most pests and diseases, it is susceptible to some leaf infections and vine weevil infestation, which can be lethal.

Yet most gardeners know that it ain’t as simple as planting a hedge and watching it grow. Problems are common, even in this hardy beauty.

In this post I’d like to outline the common issues that gardeners encounter with Portuguese laurel. I’ve been around this species as a gardener for years, and in preparation I’ve spoken with local gardeners and dug deep into academic research and my large library of tree and plant care books to bring you a reliable and PRACTICAL guide to ensuring your laurel grow as they should.

Most Portuguese laurel hedge owners have put time and money into it – so are understandable frustrated when one or two of their shrubs – or the whole hedge – looks sick or isn’t putting on the expected 18 inches of height per year.

My Portuguese laurel has yellow or brown leaves – is it normal?

portuguese laurel yellow brown leaves berries drupes
Some minimal leaf yellowing is seen normally in late summer and autumn, when the berries (which are actually drupes) appear

You’ve planted a row of Portuguese laurel and you’ve noticed that some of the leaves are changing colour – betraying their ‘evergreen’ status, some are turning yellow or brown. Why?

Firstly, all evergreens, including this shrub do lose some of their leaves on a yearly basis. This tends to happen in summer or autumn. Those older leaves that are no longer able to photosynthesize (utilise sunlight) are allowed to die off as a protective measure for the plant.

The question is – which leaves are changing colour?

Browning or yellowing of Portuguese laurel leaves is normal, provided that it occurs on the interior or lowest parts of the shrub, i.e. to the oldest or most shaded leaves, in summer or autumn. However, excessive colour change or leaf loss is a sign of stress in this shrub, as is leaf curl, stunted growth and reduced flowering and fruiting.

Only a few internal leaves on each shrub should be expected to turn yellow and drop off every year.

You’ve got a problem if:

  • it’s happening in winter or spring
  • it’s happening to lots of leaves
  • it’s seen on leaves on the outside or upper parts of the shrub, rather than the lowest or internal leaves
  • lots of leaves are affected – it should only be a few

If you’ve got a hedgerow of Portuguese laurel and one or two shrubs have more yellow or brown leaves than the others, something’s affecting those shrubs.

My Portuguese laurel isn’t growing well

What causes stress, reduced growth and excessive leaf discolouration in Portuguese laurel?

Recent planting

If you’ve planted your laurel in the last 3 years (or particularly in the last year) and are seeing yellowing, brown tips or leaf loss – or even one or two of your shrubs looks like it’s dying – it might be the actual effect of planting itself that’s made your shrub look sickly.

The most delicate time in any young tree’s life is when it’s planted in a new environment – whether it’s come from the nursery root-balled, containerized or bare-root. Flung into a spot with different soil, with roots often severed or damaged in the process, laurels can struggle to adapt and can effectively stop drawing up water temporarily. ‘Transplant shock’ is a term used to describe the extreme form of this.

While hedges should normally be planted in autumn or winter when it’s cooler, they’re often planted by landscapers in the summer, when roots rapidly dry out – which makes transplanting issues much more likely.

Frequent watering is the antidote to transplant shock. It gives the laurel a helping hand to get over this period.

Portuguese laurel and water requirements

Over time I’ve come to learn that most (but not all) of the common issues with Portuguese laurel are down to issues with water. So if you’ve got an unhappy laurel, my first question will always be ‘how much water is it getting’?

Whilst more resistant to drought than many other trees and shrubs, irrigating Portuguese laurel does require intentionality and work, particularly in the first 3 years while its getting established and is forming a root system.

To grow properly, young Portuguese laurel need to be watered every week from late spring until late autumn, unless there is heavy rainfall.

When established (4-5 years from planting) they usually only need to be watered in the summer every 2 weeks or so.

How to water Portuguese laurel

Depending on how many laurel you have, the easiest way to do this is with a drip irrigation system or soaker hose. These hoses – effectively leaky pipes – can be laid along the ground along your hedge and can be hooked up to a timer. Typically, in the summer you’ll run these for 20-30 minutes a day through dry periods.

If this isn’t possible for you (you may not have an outdoor faucet) you could deliver a large bucket of water to each young laurel every 2-3 days. Try to pour it slowly, to reduce run-off, or use a watering can if you’ve got the patience.

The importance of mulch

What’s on the ground under your laurel? It’s so important to have a good layer of mulch, such as bark chippings, covering the roots. If you’ve already planted your hedge and you have bare soil here, it’s not at all too late to add a good layer. It’s an easy win to make your hedge healthier.

Why bother?

  • it helps water to permeate down to the roots, reducing evaporation and run-off
  • it suppresses growth of weeds and grass, which compete for water (and look bad)
  • it insulates the roots against freezing and winter, and prevents them drying out in summer

A layer of mulch for a laurel hedge should be about 3-4 inches thick, except around the actual stem of the shrub, so the mulch doesn’t actually touch it. Mulch piled up against the stem can cause rot to set in. So leave a 1-2 inch gap and away you go!

Portuguese laurel and excessive water?

While it’s less commonly the issue, I’ve seen Portuguese laurel that are planted at the bottom of a garden on a boggy, squelchy site – and for that reason they haven’t thrived. They’re not as intolerant to ‘wet feet’ as some other hedge plants (particularly yew are well known for this), but they’re not going to grow well in standing water. Roots need air, and rot can set in if they’re waterlogged.

Use a small trowel to inspect the soil 6 inches down to check for waterlogging.

Unfortunately it’s difficult to address this issue except at the time of planting, when you can mix in grit or add some shingle at the bottom of the planting hole. It helps to loosen at least 5 feet width of soil when planting the hedge, particularly if it’s of a clay type – if you’ve just dug a hole and popped in the young laurel, it can almost function as an underground bucket that excessive water gathers in.

Waterlogged laurel look sickly, have curled or yellowing leaves that can drop off. They won’t grow at the expected 18 inches per year.

Portuguese laurel and soil requirements

Portuguese laurel is tolerant of a wide range of soils types and pH levels, including chalky and shallow soils.

It’s not likely that your soil is the issue if you’re having trouble with your Portuguese laurel, unless you have a clay type, which can increase the risk of waterlogging as discussed in the section above.

Occasionally, yellowing of leaves (chlorosis) can occur if you have an alkaline soil type (pH >7), which can affect the availability of nutrients in the soil.

It’s quite easy to find out the pH of your soil, and it’s relevant to the selection of so many plants and trees that all gardeners should probably know their soil pH. I use the Rapitest soil test kit – quick and easy.

It’s possible to add an ericaceous feed to lower the pH of the soil (that is, make it less alkaline), but you’re likely to have to keep this up for a long time and you may decide that it isn’t worth the effort.

Too much shade?

Could it be that your laurel is too much in the shade to grow well? It’s not likely to be the issue. This tree will grow in full sun or in shade quite happily.

Portuguese laurel, wind exposure and windburn

You might have seen newly planted laurel hedges with green fabric netting strung along it from post to post. That’s because wind can causes leaf ‘burn’ on this shrub and some basic wind protection can go a long way to preventing it.

If your Portuguese laurel has brown or withered tips on the leaves in late winter or in spring, it’s likely windburn or ‘winter injury’ caused by the leaves drying out. It may be more prominent on the side of the hedge that’s most exposed to the wind.

Unlike deciduous trees and shrubs, evergreens keep their leaves on over the cold months so are constantly losing water by evaporation (more accurately called transpiration), especially when winds are high, and the roots may struggle to access enough water to replace it.

Portuguese laurel is a salt-intolerant plant at the best of times, and spraying the leaves with salt from roads or driveways greatly increases the risk of winter injury and burn.

So if your laurel’s on an exposed site or acting as a windbreak, you may want to consider erecting some basic wind protection. But you can reduce the risk of windburn by applying a good layer of mulch over the roots (which helps water permeate into the soil and insulates the roots from freezing temperatures).

Planted too deep?

I wanted to mention this issue as it’s a lot more common than you might think – and is a barrier to many trees and shrubs becoming established.

Laurels should be planted with the root flare (the thicker part of the stem just where it meets the roots) at or ABOVE ground level – it should be visible, not buried in soil or mulch.

If your young Portuguese laurel’s planted too deep, the roots are already separated from air and water by an unnecessary layer of earth and have to grow upwards seek out surface rainwater. These shrubs can take years longer to develop a sturdy root structure and are more likely to blow over shortly after planting.

I’m planning an article on what to do when you’ve planted your tree or shrub too deeply.

For detailed information on how to correctly plant Portuguese laurel, I’ve written an in-depth article here.

Bark damage

Particularly if you have one or two laurels that are sickly or not growing well, while the rest flourish – get down and inspect the bark at the base of the trunk.

Animals such as rabbits sometimes nibble on the bark of these young shrubs. Overenthusiastic mowing or weed trimming can do the same.

Damage to trunks and stems, if significant enough, can be lethal, but sometimes trees survive it. Check out my article in which I outline this in more detail (including whether your shrub can survive it, and how to help it).

Portuguese laurel pests and diseases

While more resistant to such issues as cherry laurel, there are two common types of infection and one type of infestation that you should be aware of.

Powdery mildew

powdery mildew

Powdery mildew is caused by a fungus (ascomycete species) and causes a dusty white coating on the leaves of Portuguese laurel as well as many other plants and trees. It’s very common and a bit unsightly, but fortunately, it’s rare for it to have an impact on growth or vigor.

Cool damp weather and poor air circulation predispose to fungal infections, so regular pruning will reduce the risk.

There are commercial fungicides available for powdery mildew – an effective one that I’d suggest would be Provanto Fungus Fighter Plus. Just make sure you follow the manufacturer’s instructions.

If it isn’t too widespread, I’d recommend pruning off the affected leaves. Just clean your pruners between cuts (with bleach or alcohol hand sanitiser) so you don’t spread the infection to other parts. Anything that you prune off should be binned though, not left on the ground where fungal spores can still be released.

‘Shot hole’ infections

Portuguese laurel shot hole leaves
I only had to walk one minute from my home to find Portuguese laurel with some shot hole disease!

If your Portuguese laurel’s leaves have round holes as if shot through with a small pellet, it’s called a shot hole disease. These are caused by a range of pathogens – bacterial (particularly Pseudomonas syringae) and fungal (including Wilsonomyces carpophilus).

The holes start off as brown spots on the leaves. As the brown tissue dies and disintegrates, you’re left with a hole.

Again, this disease has mostly a cosmetic impact, and won’t stop your laurel from growing well. Treating it with sprays is more complicated, since there is a range of different types of infection that will cause it, so it’s treated through cultural methods – pruning out and disposing of affected leaves (sterilising your pruners between cuts). Keeping the Portuguese laurel pruned and tidy will improve airflow through the plant, reducing the risk of infection occurring in the first place.

Vine weevil infestation

Vine weevils nibble the edges of leaves, causing notching

OK, this is the one that can really damage and even kill your Portuguese laurel.

Vine weevils are beetles that feed on lots of ornamental plants, particularly those in containers, but hedgerows are common targets too. The beetles chew laurel leaves – you’ll see notches in the edges of the leaves (contrasting from shot hole diseases where the holes are through the centers of the leaves).

That’s not good, but it’s the larval form that feeds on the laurel’s roots – causing it to wilt and look lifeless in the cooler months, eventually causing leaf loss and even death.

How to diagnose vine weevil infestation? Well, it’s easier in spring and summer when the beetles are active – they come out at night, so take a torch outside and have a look for the black critters nibbling away. You can shake your laurel over an upturned umbrella and, er, dispose of whatever beetles fall out.

A bit more ingenuity is required to kill the larvae though. It’s these grubs that really do the damage. For this we use ‘biological control’ with nematodes – microscopic plant parasites – that will infect and kill the larvae. No chemicals involved!

I found a very short (one minute) video that shows nematode application for vine weevil.

Nematode application for vine weevil

My portuguese laurel isn’t flowering well (or at all)

Portuguese laurel flowers prunus lusitanica
Portuguese laurel flowers

Portuguese laurel should produce abundant white flowers that appear in May or June and last into July. What if they aren’t appearing?

Firstly, if you planted the trees recently, they may still be too young – they don’t usually start flowering until they’re about 4 years old.

If you’ve pruned your laurel recently, that could be the problem. These shrubs are often pruned in autumn and winter, but you risk chopping off many of the buds that would have otherwise led to those flowers in spring and early summer.

For this reason, if you want a good display of flowers each year, you should wait until after flowering and prune them back in the mid to late summer.

If the laurel’s neither been pruned recently, nor too young to flower – something else is impacting the health of your hedge and causing it stress – it’s putting its energy into staying alive, rather than flower production. If you’ve learned anything from this article, you’ll know that lack of water is the big factor to consider first, but check also for waterlogged roots. And consider vine weevil infestation – check for notched leaves and for the presence of beetles in summer.

I hope you found this article helpful! Check out my homepage and have a look at what I’ve been writing this week!

And if you’ve got this far, I’m certain you’ll find this article helpful as well:

Image attributions:

Jeff Kubina, Public domain, via Wikimedia Commons

David Short from Windsor, UK, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons

SABENCIA Guillermo C├ęsar Ruiz, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

Cillas, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

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