The Portuguese Laurel are a favourite for hedges and growing as elegant standards in a wide variety of garden situations in NZ. The Plant Company has produced this series of articles to help you get the most from Portuguese Laurel plants and have them thriving!
The Plant Company is often asked questions about Portuguese Laurels specific to NZ and these are provided and answered by team in the following articles.
The Portuguese Laurel, scientifically known as Prunus lusitanica, is a popular evergreen shrub or small tree native to the Iberian Peninsula, Morocco, and the Macaronesian archipelagos. It is widely grown around the world due to its attractive appearance and versatility. Some of its key features include:
The ideal time to prune a Portuguese Laurel in New Zealand is during summer when the plant is actively growing. At that time, it is more likely to sprout new buds and continue with vigorous growth. Pruning in winter can cause dead stems that fail to sprout and is often incorrectly recommended. The Plant Company recommends pruning little and often with light pruning in both summer and winter. Dead or damaged branches can be removed any time. Any large cuts should have pruning paint applied to reduce the chances of disease.
Portuguese Laurel plants do have problems from time to time. Therefore, it is important to understand the underlying issue(s) and have the remedies to fix the problem. The Plant Company have produced this series of articles to help you in the quest for solutions to address problems and diseases.
The main pests of Portuguese Laurel are aphids, thrips, and borer beetles. Aphids and thrips cause the leaves to discolour and often have a mottled, silvering, or bronzing appearance. Where such pests are present there will often be a black mould on some of the leaves and stems. This is a mould that feeds on the sugars released from the plant by these insects feeding. While the mould is unsightly, it does not hurt the plant and will dissipate with time. All of these pests are easily controlled with a general insecticide. Please always read the label before using any agrichemical.
Borer Beetles usually cause a weakening and ultimate death of the stem. Holes through the insides of the stems are a tell-tale sign. To control this pest the stems can be cut and painted with an insecticidal paint. The Plant Company recommends cutting stems back to below any of the boring and then applying wound paint.
Leaf Spot Fungus on Portuguese Laurel causes red or brown spots that usually starts on new growth during cold and wet conditions. The spots enlarge and change to a purple colour before the leaf tissue eventually dies. It is best controlled using a copper fungicide every 10-14 days until the disease is no longer obvious. Please always read the label when using any agrichemical.
Leaf yellowing in a Portuguese Laurel can result from over-watering, being grown in poor draining soil, or both. This can promote the disease, Phytophthora, and is discussed in the article, Why Is My Portuguese Laurel Dying? Other common causes are too much shade, or the plants have not been fed for a number of years. A liquid fertiliser can be used to correct issues quickly and should be supported with Shrub Fertiliser during spring if you think this is the cause. Pests sucking on the leaves can cause a yellowing but this is often mottled and varied across the plant.
On dense bushes the internal leaves will often yellow before being shed. This is due to a lack of light and is normal. On the other hand, when plants that have been grown in the shade or very low light conditions, then suddenly exposed to full sun, they can become bleached. In this instance, the sun has damaged some of the leaf pigments. The good news is the plant will survive, but it will look terrible for a time.
There can be many reasons why a Portuguese Laurel looks sick or is dying and it is often an iterative process to determine why. The most common reasons are presented below and organised from most likely to least likely based on The Plant Company's experience.
Black mould on Portuguese Laurel is caused by Sooty Mould Fungus. This fungus feeds on the sugars released by feeding insects such as aphids and thrips. While the mould is unsightly, it does not hurt the plant and will dissipate with time if the pests causing it are controlled. Most pests that feed on Portuguese Laurel are easily controlled with a general insecticide. Please always read the label before using any agrichemical.
When Portuguese Laurel plants are grown in wet soils or exposed to prolonged wet through over-watering, the disease, Phytophthora, can take hold. Phytophthora attacks the roots and causes the plant to eventually die. The tell-tale symptoms are yellowing of the leaves, drooping foliage even when the soil is wet, discolouring of the stems, and plant collapse. This can happen over several months during any season and progressively gets worse. This is all resulting from the root system being progressively weakened by the pathogen. Gardeners will often mistakenly think the plant needs more water. Unfortunately, adding water only accelerates the problem prolonged wetness was generally the cause in the first place.
Often the disease will start to show several weeks after a prolonged rain event. It can also occur when plants are regularly over-watered, or planted in soils that are poorly drained or that hold too much moisture (e.g., clay soils). Therefore, good drainage is essential and sites where drainage is poor should be avoided. The article, Fixing Poor Drainage On A Clay Soil gives good advice on how to correct drainage.
Treatment for Phytophthora can be a hit and miss exercise as there are no silver bullets. However, if picked up early, The Plant Company has experienced some success using Transformer. Transformer has fungicidal properties and when used as a soil drench 2-3 times, plants can sometimes recover. However, if the plant is too far gone, The Plant Company recommends removing the plant entirely, and using Transformer as a soil drench before putting in a new plant. Of course, the drainage or watering issues will need to be addressed so the problem does not manifest again.
Growing a Portuguese Laurel standard takes some thought and planning to ensure you get what you are after. Factors such as the spacing between trees, desired height and width are all important considerations. The Plant Company have produced this series of articles to provide advice for trimming a Portuguese Laurel so you can manicure with confidence and success.
The decision about who far apart to plant a Portuguese Laurel Standard depends on whether you want them to merge or become discrete balls. It also depends on how big you want the ball (or other topiary shape) to be. Generally, the balls are contained to no more than a 1 m in diameter at maturity. Therefore, for discrete trees with a 50 cm gap between the balls, the spacing will be 1.5 m between trees. If the trees are to merge such that a pleached hedge look is the goal, the spacing now becomes 50-75 cm apart depending on your budget. The Plant Company typically recommends the closer spacing to achieve a dense hedge faster, particularly as Portuguese Laurels can be somewhat slower growing.
Creating a Portuguese Laurel standard requires both patience and a straight, single-stemmed plant to start off with. The plant is staked to grow with a straight trunk to just past the mid-height of the topiary (i.e., ball). All the side branches are trimmed off to about 10 cm above the mid-point of the topiary. The top of the plant is cut off just above the mid-point of the ball to encourage sprouting just below the cut. As the new stems grow, they are routinely “tipped” (i.e., the top bud is pinched out) to encourage more shoots. All the time, the ball is progressively shaped until the desired size is achieved. This process can take three years (or more) to complete. If all this seems too hard or you don’t have the patience, contact us and we can generally supply your needs.
When planting a Portuguese Laurel Standard, choose a full sun or partial shade position with good drainage. The hole should be dug to at least 50-75% deeper and wider than the container the plant is currently growing in. A planting spade makes the hole digging a lot easier. The Plant Company recommends incorporating compost or sheep pellets into the soil to provide additional organic material, but this is not essential. Do not put fertiliser in the bottom of the hole, rather spread that on the soil surface after planting, and preferably do this when the plant is actively growing in spring.
Remove the plant from the container it is growing in by either pulling it free or by cutting the bag. We recommend cutting the bag, especially for larger grade plants, to minimise any chance of damaging the roots. Once out, you need to assess the roots before progressing. If they are not all bound up and haven’t been growing in a circle within the container, place the plant in the hole without removing any of the growing media or cutting the roots. You can tease them apart if you want but this is not essential. If, however, the roots have been circling the inside of the pot or they look totally root bound, simply cut through those very outer roots on either side. You don’t need to be any more aggressive than this or remove any of the growing media. You can try and tease the roots apart, but this generally breaks them which is why we cut them. NB: cutting roots is not essential, even if the plant is root-bound as explained in our article, Managing Rootbound Plants.
Now place the plant in the hole and make sure it is level with the soil surface before filling in around it. If it is above the soil surface, dig more out. If it is below, put in more soil and retest the level. Once the plant is set level with the soil surface, add more soil gradually and firm it around the plant using gentle pressure as you go. Scatter Shrub Fertiliser across the soil surface after planting and the give the plant a good watering.
The Plant Company recommends using a stringline and spirit level when planting multiple trees to achieve the perfect line and the formality desired. If the site is wind prone, you may need to stake the tree until they establish.
A Portuguese Laurel Standard is simply a tree that has had branches removed from the stem to leave a trunk with foliage above. Nurseries will create a Portuguese Laurel Standard with clear stems ranging from 50 cm up to about 1.5 m tall. The most common standardised height is 1-1.2 m. Nurseries will also clip the foliage into balls or other topiary forms with the goal of producing a consistent grade of trees.
Whether you need assistance finding the plant you’re looking for or you simply want to know more about who we are and what we do, we invite you to get in touch with us today. A member of The Plant Company team will get back in touch as soon as possible.
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