Before you prune your Berberis, get a tough pair of gloves! The thorns are very invasive, and it is difficult to to prune this plant without suffering.
Deciduous Berberis need pruning at different times to the evergreen varieties. We take you through the process of pruning at the right time, done in the right way.
This group of Berberis make their flower buds the year before they actually flower, so it is important to allow the flowering wood as much time as possible to produce suitable branches for flowering the next year.
If you prune these Berberis too late in the year, then they will not have time to do this. When to prune Berberis is as important as how to prune.
Berberis thunbergii and all other deciduous Berberis need pruning right after they have finished flowering - late spring or early summer.
Together with this, if you prune these Berberis too early (before flowering in spring) you will prune out all of the flower buds for the current year.
Right after flowering, prune by taking out all of the flowered stems - pruning well back into the shrub. At least one third of the newly flowered stem should be cut out. It will soon then produce vigorous new stems to grow through the summer - ready for flowering the following spring early summer season.
During this Berberis pruning operation, it will also be good practice to cut out some of the older stems each year - by pruning right down to ground level. Around one third of the old Berberis stems should be pruned down in this manner.
This will make for a ready supply of new vigorous growth for flowering in following seasons. Prune the following Berberis in this manner >> Berberis thunbergii types - atropurpurea, Bagatelle, Aurea, Crimson Pygmy, Golden Ring, Rosy Glow, Sparkle, and all others in the thunbergii group. B. Ottawensis types, B. aggregata, B. dictophylla, B. jamesiana, B. rubrostilla.
Deciduous Berbers types can be a bit temperamental if cut back hard. Most of the time, they shoot into new growth, but there have been times when I have lost an old overgrown Berberis. Rather than take a chance with a valued shrub, far better to cut it back hard in three stages.
At the start of growth in spring, cut back one third of the Berberis branches. Do this evenly around the shrub. After around 6 weeks you should see new growth starting down at basal level, it is then safe to cut out a further third of the shrub - that is half of the remaining Berberis plant branches , and after a further six weeks it will be ok to cut out the remainder of the older branches.
Most varieties are best trimmed right after flowering. With Berberis stenophylla - a great hedging plant - I tend to simply trim up the sides - leaving the long arching sprays at the top for a great display the following year.