If pruning shrubs so they look like a globe, a cube or Mickey Mouse is something better left to zealous gardeners with lots of time on their hands, even the most laidback gardener may feel the need to prune a shrub or two every now and then.
That’s because, if you never prune them at all, most deciduous shrubs start to decline in appearance and performance. This takes place over time. Some look just great for 10 years or more, others are starting to look shabby after just 4 or 5 years.
It happens because their older branches flower less and less, yet they shade out the younger, healthier branches that should be taking over. This gives the shrub, originally so symmetrical, an irregular, uneven appearance and reduces bloom. If it’s a small fruit, like a blueberry, honeyberry or currant, you’ll notice it’s no longer producing as many berries as it used to.
To give Mother Nature a hand, it can be useful, about every 4 to 10 years (annually for raspberries), to cut the oldest branches—that is the tallest, thickest ones—back nearly to the ground (about 6 inches/5 cm). Removing the older branches will stimulate the shrub to grow back vigorously, giving it the dense, bushy appearance it used to have and with much more bloom.
Renewal pruning can be done in any season, but it usually carried out after the shrub blooms, so in early summer for shrubs that bloom in spring and in early spring for shrubs that bloom in summer or fall. In the case of berries, it’s done at the end of winter.
In shrubs where the difference between old and young branches is very obvious (roses, lilacs, most small fruits, etc.), it’s easy enough to selectively remove the old branches. This is called thinning. Just cut them back almost to the ground and let the others continue their growth.
For shrubs where both young and old branches intermingle in an incomprehensible tangle, such as spireas and potentillas, or a shrub that has been neglected for a very long time, like an old lilac that no one has pruned for 20 years, it’s easier to carry out what is known as renewal or rejuvenation pruning: pruning the whole thing, both young and old branches, down to about 6 inches (15 cm) from the ground. You may well need a saw for the larger branches! Do not be afraid: the shrub will grow back and in fact, will soon be as attractive as it ever was: symmetrical, floriferous and, in the case of fruit shrubs, prolific.
For your own comfort, do this kind of pruning on a cool, cloudy day … then hop back into your hammock!