Pyracantha are grown in a number of different ways, stand alone shrubs; hedges; wall plants; screening and small trees, so it is as well to know a little about how they flower and subsequently berry, before the act of pruning or trimming.
They have the advantage of being fully evergreen shrubs that have masses of creamy white flowers in early summer, with masses of orange to red berries from late summer. One wrong pruning session can wipe out flowers and berries for at least a year!
Firethorns flower on stems grown in the previous year or older. They do not flower on new stems made in the current year. Typically, new stems start to emerge in May/June – immediately after flowering. Those stems will then grow for the rest of the year – maybe 18-24in (45-60cm) long producing dormant buds that hold the flower trusses for the next year. If you prune them off, you are pruning away the flowers for the following year.
Suitable for pruning all common varieties, including 'Mohave' 'Red Column' coccinea types and atalantioides.
Pyracantha berrying on stem grown the previous year.
Most varieties will flower the full length of the shoot, so it is possible to prune the shoot back halfway, and still leave plenty of flower bud developing for the following year.
Wear strong gloves, for the thorns are sharp and vicious, with the pain lasting several days. The thorns are strong, but it is possible to have the tip of the thorn impregnated in your skin. It is not suggested as a repellant hedge for nothing!
The pruning method is quite simple, but needs to take into account everything that has been written above.
Ideally, and depending upon how you want your shrub to grow – formal shape or informal. If the pyracantha is established, then in late summer, cut back any wayward stems to the developing berry trusses – allowing and. Most of the stems can be cut back halfway – still allowing plenty of berries to remain on the shrubs.
If you can allow a large informal hedge, trim back the shoots to wherever you want - allowing the forming berries to e visible. This is ideally carried out in late summer as the berries start to develop.
For a formal, restrained hedge, trim with a hedge trimmer or clippers two or three times in the growing season, back to within 6in (15cm) of the new framework. Start this immediately after flowering, so that you can see the faded flower trusses which will go on to produce the berries later in the year. You will obviously lose much of the flowering wood for the next year – but there should still be enough to ensure a good display – even as a formal hedge.
Pyracantha shrubs are not climbers, but they can still be grown against a wall or fence easily, and are probably one of the most popular of all wall plants.
They can be grown as wall plants or formal shapes, by training a main framework to where you want, and then ‘spur’ pruning to allow for a good display of flowers and berries.
Spur pruning is simply cutting or trimming new stems back to within a few cm of the main framework branch. The spurs can be as long or short as you wish.
The general trimming back can be carried out a few times in the year – similar to hedge trimming – ensuring you keep some of the stems intact for training if you want to extend the basic framework; along a wall; up a pergola, or to increase the height of a free-standing specimen.
The main cutting back, should be carried out in July or August, when it is possible to see the forming berries on the main framework. Cut back the new growths, allowing enough short stubs (spurs) to remain with plenty of berries. Any new growths after this late pruning will be short enough not to spoil the appearance, and will develop flowering wood again for the following year.
If you have inherited a wayward shrub or wall plant – or simply want to start again – it is possible to hard prune (hack even) back to within 60cm of the ground. Likewise, a ‘go it alone branch’ can be cut back to the main trunk.
This is best carried out early in the year, but in reality can be done at any time in the growing season. The worst that can happen is that you have no flowers or berries for a year. Cut back in late spring, and plenty of new flower branches will develop for the following year.
Growth will normally be quick rapid, so make sure that you carry out any training of shapes that you want by selecting the long branches you require – and discard the rest!