New wood or old wood?
When should you prune your shrubs and vines? Well, the answer lies in the question, "Does it bloom on new wood or old wood? Many varieties of the same genus may bloom on one, and some in the same genus will bloom on the other. Take clematis for example. Some species of clematis bloom on new wood, some bloom on old wood, and some on both! If your vine or shrub blooms in the spring, then it is blooming on old wood that grew last summer, as it has not had time to make new wood, yet. If your shrub or vine blooms in the summer or fall, then it is blooming upon new wood that grew this year.
Why prune at all? Well, some plants grow themselves lots of vines and few flowers. Pruning forces it to flower more. But, be careful. If the plant gets stressed with heat and drought, then severe pruning might stunt it mightily and even kill it. People in kinder climates may advise pruning because they get so much rain the plant gets too big for it's britches so to speak, and all it's energy goes into branches and leaves. But here in Central Texas, that is not our problem. So the idea is to kindly prune, and leave the poor bush some leaves. It needs leaves to make energy, and if it is bushier, it will even shade the ground and cool its own roots. This shade will also help hold in some moisture. If you prune all it's shade away, it will feel the heat more. Cooler roots are very important for the plant's vigor. (Unless it is desert hardy, a thick mulch will help everything grow and you 'll have a happier garden).
Some vines are very aggressive in our southern climate. Be careful where you plant crossvine or trumpet vine, honeysuckle, or pyracantha. Also, where you plant snailvine, or passionvine. Some of these are listed as exotic pest species, others are native pests, if you know what I mean, but you can't beat them for vigor, hardiness, and lovely flowers and fruits for the butterflies and birds. These vines you can cut back as much as nearly to the ground, and they will still grow and flower. Other shrubs might get pruned by nature. For instance, my Texas Mountain Laurel bush got webworms last summer. They had eaten all the tops of the tender stems off, before I noticed, and sprayed the buggers. Now this year, it is only blooming around the lower fringes. The webworms had eaten all this year's flowers off! I didn't know that Texas Mountain Laurel got webworms as it is such a pest free native shrub! Well, I'm on it now! The same with my yellow Banksia rose. Cutting ants ate off almost all the leaves last summer before I discovered them at it one morning when it was cloudy, and there was the trail of ants trotting along with it's newest tender leaves! I followed the trail, and found the nest under the house where I destroyed it by pouring Sevin mix down the tunnel. Now this spring, it's barely blooming. The dang ants ate off all the flowering buds!
Many species roses like the Banksia, and some climbers and old garden roses bloom only on old wood. (The stems that grew last summer, remember?) These are the roses that only bloom in the spring. It's these bushes and shrubs that you want to prune just after flowering, and not before, or else you'll be pruning off all the flowers! Well, there you have it. New wood bloomers are the plants that bloom in the fall, old wood bloomers are the plants that bloom in the spring. Now you know when to prune which roses, clematis and everything! Easy! But what about if it does both, like many roses and shrubs? Well, take your pick. When does it bloom with the biggest flush? Then treat it accordingly, or don't prune at all like me. Personally, I don't bother. Nature does enough of that for me.