The broom, or cytisus praecox, is a shrub that can grow anywhere from three to about ten feet tall. It has angled stems, small leaves and bright yellow spring flowers. There are several varieties but the most common are the Scotch and Spanish. Scotch has a five-sided stem while Spanish appears almost round.
These small-to-large shrubs grow very quickly. This fast development, along with a wide branching root system and thick stems, has caused the plant to become quite invasive. This is why pruning broom is essential, whether you just want to tidy it up or cut it right back.
Broom responds well to pruning. This may be required due to broken or diseased branches or it may just have outgrown its space, becoming wild and untidy. But, you must know when and how to prune your broom to avoid missing your chance.
When to Prune Broom
It is important to start trimming the tree while it is still young. If you start before it is mature and do this annually you will keep it looking its best. If you leave this until it is fully grown, it is too late to avoid it looking dishevelled and you will be unable to reshape it by trimming.
Broken or diseased branches can be pruned at any time but when pruning the size and shape the best time for this is at the end of May, after flowering. If you do this in autumn or winter you will reduce the number of flowers your shrub produces the following summer.
How to Prune Broom
If you want to rejuvenate your broom through pruning you need to select about one third of the branches, divided evenly over the shrub, and cut these down to about 40 cm from the ground.
Repeat this process the following year, selecting about half of the remaining ‘old’ branches for removal.
In the third year the last of the old branches can be cut down and now the entire plant will then have been rejuvenated.
Of course, you may simply want to trim your broom into shape, or prevent it from becoming larger than intended. However, if you do not prune the broom on a regular basis, vigorous pruning is still recommended every three to four years. This means cutting or sawing all branches down to a height of approximately 40 cm. Take care not to cut beyond where the plant begins to branch, as the shrub will then be bushier as it grows back.