Evergreens: Our Head Gardener answers queries
January 31, 2020
Nurtured in Norfolk’s gardening expert Martyn Davey answers all your questions.
If you would like any horticulture query answered please do e-mail our head grower at firstname.lastname@example.org to add your thoughts to our horticulture hacks.
S.O.S. please what must I do with my evergreen Azaleas which have been in the garden about 40 years. They have always done well, in front of the deciduous ones which so far are fine.
They’re in the right type of soil and for years they thrived until this last two or three years. They have never been pruned and as they are coming to the end of winter they are not looking so good this year, obviously sick as you can see on the sample enclosed.
Do you think if I cut them back hard would they survive, or must I dig them up and burn them, to stop this spreading to the deciduous ones? Can you help please?
M. Clyaton, Kings Lynn.
Once established, most evergreens are fairly low maintenance and need little or no regular pruning. Pruning, when required, is generally carried out in mid to late spring after flowering.
Many small shrubs such as lavender, and heathers (Calluna, Erica) are generally short-lived and will need replacing after 10 years or so. These shrubs flower on new wood, so pruning these plants annually will improve flowering and extend their life and prevent them from becoming too woody.
Larger shrubs, such as rhododendrons, generally require very little pruning, except for the removal of unhealthy, dead, diseased and damaged shoots. Likewise, slow-growing shrubs also require little or no regular pruning, except the removal of unhealthy shoots in mid-spring.
Evergreens that are still flowering or about to flower in mid-spring can be left until flowering has finished.
Prune out any diseased, damaged or dead shoots using long-handled loppers or a saw if necessary, and finally, thin out crowded shoots and any badly positioned ones that spoil the shrub’s appearance. After pruning, plants benefit from mulching and feeding. Use either a general-purpose fertiliser or specialist rose or other high-potassium fertiliser.
Azaleas require pruning immediately after flowering, along with many other shrubs including Berberis, box (Buxus), Camellia, Ceanothus, Choisya, Daphne, Hypericum, laurel (Prunus laurocerasus and Prunus lusitanica), Mahonia, Pieris, Rhododendron, Viburnum tinus.
Winter, spring and early summer-flowering evergreens such as Rhododendron and Camellia are best left unpruned except for removal of unsightly shoots and deadheading, unless some shaping is required. Do this by lightly cutting back shoots after flowering. Deadheading and removal of dead, damaged and diseased growth can be done at the same time.
If your garden is full of neglected shrubs or have a plant that is overgrown and choked with branches, you can try to rejuvenate it by pruning. Some shrubs can be severely pruned just as growth begins in mid-spring. Spotted laurel (Aucuba), box (Buxus), camellias, Choisya, Euonymus, hollies, Pieris, laurels (Prunus laurocerasus and Prunus lusitanica), Viburnum tinus and yew all tolerate severe pruning to near ground level.
Other evergreens are often best renovated over several years, removing one-third to half of shoots to ground level, and reducing all other shoots by one-third in the first year. Over the next couple of years, each year remove half of the older shoots to ground level. Following renovation apply a general-purpose fertiliser and mulch and avoid drought stress in the following season.
I am sure your Azaleas will come back very well from a good hard prune this will remove much of the lichen that has grown on the branches and encourage them to flower better.
Jobs for this week
Divide clumps bulbs such as snowdrops, and plant those that need planting ‘in the green’
This is the wonderful time of year when we chit potatoes to get them ready for planting as early as mid-March.
Prune hardy evergreen hedges and renovate overgrown deciduous hedges they to get this finished before the end of the month as the birds seem to be getting ready to nest.
Martyn Davey – Head Grower