It’s the warm week in January! Quick! You want to be outside, your roses are all sound asleep… Prune them!
I call this Rose Pruning Week for exactly that reason: your rose bush and everything else in your yard is ripe for the snipping.* You can snip a little, you can snip a lot, it’s up to you. There’s just one group that you should NOT snip this week: do NOT prune your spring bloomers. Azaleas and lilacs and magnolias and other spring blooming woody plants got their flowering outfits laid out last fall. If you prune them now, they won’t replace the lost flower buds until this next fall, so you’ll miss a year’s bloom. Spring bloomers get pruned after they are done blooming.
There are three kinds of pruning: shaping, maintenance, and rejuvenation.
Shaping is just nipping off the tips. With my houseplant ficus trees, they keep trying to grow up, but my windows only go so high, so I prune off the terminal buds in general and especially the highest ones. The terminal (end) buds usually get the lion’s share of the growth hormones, so with them gone, the axial (side) buds get a nice boost. I end up with a fuller, thicker tree…. that fits in my window.
On less woody plants (begonias, geraniums, jades), this kind of pruning can be done with your fingers by pinching off the top growing bit, or sort of wiggle-snapping it.
Maintenance pruning can be thought of as “aggressive shaping”. Here the goal is not just to encourage a particular sort of growth, but a particular sort of RE-growth. You actually remove lengths of stem. For sidewalk hedges, this means thinning out the top and pushing it back so you have more of a trapezoid than a rectangle, which lets the whole shrub receive sunlight.
For blackberries and lilacs and forsythia, this means removing some of the older “trunks” in order to let the younger ones take over (blackberries fruit on two year old wood, so don’t take the “not young but not old” stuff). Yes, lilacs and forsythia are spring bloomers. It’s your call on the lilacs. On the forsythia, there are going to be so many blooms anyway, if you are itching to prune it mid-winter, go for it.
All three of those examples happen to be ones where you’re removing the oldest branches all the way down at the ground. A different maintenance pruning example would be fruit trees. Many of our favorite fruits are in the rose family, and that family is fairly susceptible to molds. A great way to keep molds at bay is to improve air circulation, which has a nice side effect of also letting more light deeper into the tree. With apple trees, the old rule of thumb is that you want to be able to throw a basketball through the tree. Perhaps with cherries, quince and other smaller fruits, we can say tennis ball or baseball instead, but the gist is the same.
Rejuvenation pruning is not something every plant tolerates. The older particular pieces of wood get, the less receptive they are to rejuvenation pruning. In this snip-style, you take the whole thing to the ground (or a few inches above) and it resprouts with vigor and health. This is great for forsythia gone wild, lilacs that have really dwindled, and all the decorative grasses. Just like in coppicing, what comes back is generally very slender and straight at first, and then branches again later, higher up. Fall (or late summer) raspberries fruit on one year old wood, so this is great for them. Do you have a good mid-summer raspberry crop? Those fruits are on 2nd year wood, so DON’T do this to them.
So there you have it: winter pruning for fall and summer bloomers. Now go outside, enjoy the reprieve! Winter will be back, whether you enjoyed this break or not.
*Yes, quite a few rose books will tell you to wait until bud swell or when the forsythia bloom or what not to prune the roses. The assumption there is that it’ll be easier for you to see the buds and so prune to leave an “outer bud” as the top bud. (a) That’s an aesthetic consideration relevant only to shrub roses and (b) you can see the freakin’ buds right now. Look at that branch and tell me you can’t tell where the leaves are about to come out. Of course you can.