Straight or slanted cuts for roses?

I was recently examining Royal Horticultural students for their Wisley Diploma and was discussing the rose pruning practical with my good friend and expert horticulturist, Mr Ray Broughton. 

We were discussing the assessment criteria and Ray informed me that it is RHS policy to use straight (horizontal) cuts when pruning roses rather than slanting ones. Until recently, we were advised to make slanted cuts at an angle of 45 degrees to the main stem to prevent water settling on the pruning cut and encouraging fungal infection. Now I have never agonised over the angle of cut as rose stems are seldom vertical and as long as the cut is made cleanly just above a bud with a sharp pair of quality secateurs, you will be fine. 

My point is that you will never find consensus amongst horticulturists about rose pruning, there are still some who advocate the use of hedge trimmers ( I do not) and  have their own techniques at variance with others. If your rose pruning technique works, stick to it.

There are so many ways to prune roses

Make tidy cuts

I am always on the lookout for good and bad pruning and came across this poor specimen of Elaeagnus x ebbingei. The untidy pruning cuts looked a mess and worse still, they will take a long time to heal and this will greatly increase the risk of bacterial and fungal infection. This is a mistake that could prove fatal for the plant. I am sure that a badly sharpened hedgetrimmer was used to butcher this plant. 

If you must use a hedgetrimmer on your shrubs, please tidy up the pruning cuts with a sharp pair of secateurs, treat your plants with respect and they will reward your efforts.

  

Pruning rambling roses

Rose pruning can be a little daunting with so many different types. Rambling roses are vigorous plants that are used for scrambling into trees or covering pergolas or garden structures. The curved thorns act as grappling irons to gain purchase on bark or woodwork. A relatively plain shed or garden building can be transformed by a covering of a rambling rose. 

Rambling roses need to be distinguished from climbers as they have different pruning requirements. Ramblers tend to be very vigorous, have semi-evergreen foliage and flower in a single flush. By contrast, climbers have stiff stems and are usually repeat flowering. There are exceptions to these rules, some ramblers are repeat flowering and some climbers have only a single flush of flowers.

Left unpruned, ramblers often become a mess of tangled shoots and as vigour declines, so does flowering. You need to be prepare to make some some hard pruning cuts to keep your ramblers from becoming triffids and I suggest using both secateurs and loppers. 

Pruning ramblers is about removing flowering shoots close to their point of origin at the base of the plant immediately after flowering. Do not overwork your precious secateurs, a pair of loppers will save time and avoid twisting the blades of your secateurs. What proportion of flowering shoots you remove depends on your requirements, if the plant is threatening to outgrow its allotted space, take them all out leaving the new shoots to flower next year. If there is enough space to accommodate them, leave the majority of flowering shoots in place and take out either a quarter or third of them each year taking out the older shoots on a rota basis. Side shoots are reduced by about a half. 

Pruning ramblers appears brutal and is not a task to be undertaken by a gardener who is timid with the secateurs. 

Rosa mulliganii - a typical rambling rose needing pruning after flowering to keep in check. 

How not to prune a spring flowering Spiraea

Spring flowering Spiraeas usually have naturally arching growth giving them as graceful habit. This habit can be ruined by thoughtless pruning, I came across this specimen recently. The poor plant had had the hedgetrimmer treatment cutting off the young growth and destroying its graceful habit. No doubt the handiwork of a 'professional gardener'. Please avoid the temptation to prune shrubs like hedges, the time saving is minimal and the effect unforgivable. 

Dealing with Salix caprea Goat willow

Often when I look at shrub plantings that are maintained by contractors, the goat willow (Salix caprea) is able to grow as a woody weed amongst the shrubs and it is either ignored or is given a annual 'prune' with a mechanical hedgetrimmer. Salix caprea is a common weed of nursery plants and may have been present in the pot when the plant was planted out. The seeds of this willow are commonly distributed by wind  and the irrigation water of nursery plants that are watered from water from a reservoir. The plant may be welcome in the wild but rapidly swamps shrubs if left to flourish. 

The ideal solution is to pull up small seedlings but if the weed is too large to do this, either cut back the willow to ground level and apply an approved  systemic weedkiller to the stump or remove it with a mattock or grubbing axe if this is possible. The sooner the weed is treated, the better. 

The goat willow needs prompt removal to prevent it becoming a menace in shrub plantings. 

Pruning Paulownia tomentosa

Paulownia tomentosa (foxglove tree) is a spectacular tree when grown for its very large, handsome leaves or its fragrant foxglove like flowers in spring. It is only in sheltered locations in southern England that the flower buds that are formed in autumn survive the winter unscathed to produce a stunning flowering display. In places that do not experience a mild winter, it is best to forget about flowering and give the plant a hard prune in spring to encourage strong new growth producing exceptionally large leaves. 

Large, handsome leaves from a Paulownia tomentosa hard pruned in spring. 

A Paulownia tomentosa pruned hard in spring. 

Pruning an established Choisya

Choisya are firm garden favourites that are relatively undemanding in terms of maintenance. They can be depended to put on a showy display of white flowers in spring. They are one of those plants that can put on a lot of growth particularly in a sheltered location. They are tolerant of quite hard pruning once established provided that the plant is healthy and growing strongly. Once flowering has finished, a light prune will encourage a second flush of flowering in autumn. 
if plants have been pruned more severely, an application of a Potassium rich fertiliser  will help to ripen wood and improve the frost resistance of young shoots. 

Now this specimen of Choisya x dewitteana 'Aztec Pearl' has finished flowering, it can be pruned if required.