August 23 2014 Latest news:
Martyn Davey, Head of Horticulture and Design, Easton College
Tuesday, May 8, 2012
Question: I have two camellias growing in ericaceous compost in large pots on a south-facing terrace. One is about six feet tall, with large semi-double flowers and thick, roundish glossy leaves, the other perhaps eight feet tall, with smaller, fully double pink flowers and smaller, thinner leaves. They have reliably bloomed profusely in late February every year but this year, when they were in full bud, they were cut down by the great frosts. They still have all their buds, but it is clear that these will never open. The smaller tree has lost many of its leaves, but still has decent cover. The taller plant has almost no leaves left at all. How should I deal with them now, especially the almost-denuded one? (I Arnold, via email)
Camellias are one of the most popular winter-and spring-flowering shrubs, providing a vivid splash of colour when little else is in bloom. Although they need acid soil, they are easy to grow in containers of ericaceous (acidic) potting compost.
Camellias are woodland plants that grow best in shelter and light shade, although with careful watering they can be grown in sunny positions.
They prefer free-draining conditions, with plenty of organic matter in the soil. Being ericaceous plants, camellias require an acid soil. If your soil isn’t acid try growing your camellia in a container.
Like other early-flowering shrubs, camellias form flower buds in late summer and autumn, especially on new growth. Pruning is best done in spring, immediately after flowering stops. With yours that has lost its leaves it is best to wait until you see signs of new growth and then prune back to that. Where an overgrown plant needs to be renovated, hard pruning is safe and reliable.
Despite being easy to grow, camellias are occasionally subject to problems.
Failure to flower and loss of flower buds can be avoided by providing good growing conditions: Water during dry spells in late summer when flower buds are forming, mulch with an 8-10cm layer of chipped bark or leaf mould in late winter or early spring, and move container-grown camellias out from under the eaves of the house in late summer or autumn so that they catch the rainfall.
Do not feed camellias later than the end of July, as excessive or late feeding can lead to bud drop. Some natural bud drop may occur where too many buds have formed, particularly with double-flowered cultivars. This is nothing to worry about.
Protect tender cultivars with a double layer of horticultural fleece in winter. Flowers can be damaged by rain and frost, but Camellia petal blight may also be involved. Like many evergreen plants camellias are vulnerable to windy, cold or wet weather, developing wind scorch, oedema or a coating of algae.
Nutrient deficiencies may cause yellowing foliage where alkaline soil prevents uptake of certain nutrients.
Camellias can succumb to pests and diseases, including Camellia yellow mottle virus vine weevil, camellia cushion scale, camellia gall and the root diseases Phytophthora and honey fungus.
As with all evergreen shrubs, each year a proportion of the foliage is shed, usually in spring and summer. This is normal and not a cause for concern.