One plant which is enjoying great popularity at the moment is the box plant, or Buxus. These are easy to grow, needing no particular type of soil, and are ideal for using as topiary plants in pots, or as slow growing hedging. While they are very easy to care for, they are like any other plants, and do need some attention!
Many people are familiar with the dreaded Box blight, or Cylindrocladium buxicola, which has become a problem in recent years. However, blight has been ruled the cause of many problems which affect Buxus plants, but in my experience more common issues have been ignored. Ground conditions certainly affect the plants more often than blight – box plants will be yellow and stunted if the ground is too heavy and waterlogged. Similarly, plants will lose their leaves if the ground is too dry, and can do so very suddenly. Unless there is visible new growth, you will not notice a Buxus plant wilting if it is dry, which is a regular occurrence in pots, but also in sandy, or poor, soil. The plant will shed its leaves, seemingly for no reason, and blight will be blamed, as opposed to poor watering! Using pots, such as the Elho ‘Loft’range, will help in this regard, as there is a water reservoir in the bottom of the pot. It is also advisable to use John Innes no. 3, mixed with some water retaining Vermiculite, (optional!) Another common problem with box plants is whitefly. This little pest can really wreak havoc, as it goes unnoticed in the dense growth for a long time. Again, it would seem that your plant is losing its leaves for no reason. However, on closer inspection, you will notice white webbing, or white fluffy deposits, which is evidence of whitefly. If the plant is shaken, a cloud of tiny white flies will emerge. These are quite difficult to control, (similarly in houseplants, where they are prevalent), and a systemic pesticide, such as ‘Bug Clear Ultra’ is more effective, as opposed to a topical spray. If using a spray, ensure a good coverage of all leaves and stems. Wind scorch will also cause your plants to look poorly, turning them a shade of ochre, which looks very similar to underfed plants. The plant will grow out of this discolouration if it is sheltered, or fed. If these problems have been eliminated, and it is blight you are dealing with, a product such as Provanto Fungus Fighter is an option, as well as quite a few organic sprays which are now available, such as ‘Westland Growing Success funguscontrol’, or ‘Ecofective Bug and Mildew Control’. The symptoms to look out for are brown/black spots or lesions on the leaves, which then become dry and fall off. It is advisable to cut out, and burn, any sections that are affected. A hard prune back will encourage regeneration of weaker plants, but if they are too far gone, it is best to take them out altogether. The spores remain viable for five years, so good hygiene and strong plants are key. Pruning your plants on a very dry day is preferable, as blight spreads in humid conditions. Keeping tools clean and sterilized is also advisable. Clean up any dead leaves, and feed with a high-quality slow-release fertiliser, such as the specialist ‘Top Buxus’ products, which are formulated by buxus nurseries themselves. Alternatively, Westland Buxus 2in1 is a specially formulated liquid feed.
Finally, another pest which has been active in the last few years is the Box Tree Caterpillar. These small, but numerous caterpillars can decimate a hedge in no time, and while the plants do tend to survive, it can take several years to recover completely. The best way to tackle this problem is prevention, and there are two ways to go about this. Firstly, and most effective, is to use Moth Traps. These emit a pheromone, attracting the male moths, which are then trapped. Use from mid-April until the end of August. Secondly, using a systemic pesticide, such as ‘Grazer’s Butterflies and Caterpillars’ will make the plant unpalatable to the caterpillars, thus preventing damage.