What does it mean that a plant grows on old wood or new wood?

I have heard people tell me when for example I am pruning my crepe mrtyles in the fall or hydrangeas. Dont or do because it grows on old or new wood. I dont know what the hell they are talking about. Would somebody please explain about this in idiot language? thanks.



Also when is the best time to prune most stuff?
What does it mean that a plant grows on old wood or new wood?
The terms old wood and new wood refer to the current year's growth. For instance, butterfly bush only blooms on new wood. If you don't cut your butterfly bush down to 18 inches in the spring, you will have a big bush with very few blooms. The plant only blooms on branches grown that year (new wood).
Reply:New wood is that year's growth. If you have a bush that flowers on new wood, prune it completely every year, so that the new growth in spring will then be covered in flowers (if you don't, you'll get flowers on the new bits, but lots of old wood with no flowers underneath).



If your plant flowers only on old wood, then it means that it needs stems over a year old before it will flower. If you prune it back every year, then it will never flower. You have to prune it every two years, and/or only partially. Say it grows a foot of new stems in year 1. They stay bare. Unpruned, they then flower in year 2. At the same time, the plant grows new stems, which will not flower. If you prune in year 2, you must only prune the old wood, not the new. Then in year 3, last year's (unpruned) new wood will flower, as well as any old wood you left unpruned. And so on.



That's why it's so important to know whether a plant flowers on old or new wood. Flowering on new wood is more common, which is why you can prune roses, fuschia and clematis and so on right down to the ground every year, and still have them flower. But if something flowers on old wood, like orange blossom, or lilac, then don't prune any new wood away.
Reply:New wood is this years growth. Old wood is last years growth or older.The best time to prune is after bloom.I do not prune my hydrangeas...I wait untill spring...I wait for new growth and then snip off the dead wood
Reply:Not to sound patronizing, but old wood to me just looks old. New wood is new growth, usually greenish, or at least smoother and more pliable, than the surrounding thicker, drier, old wood.



Pruning for plants varies by what you are pruning. I don't think there is a preferred time to prune most everything. Sorry I can't be of more help on that one!



Good luck!
Reply:Old wood is usually brown rigid and weathered whereas the new wood is still green and flexible.



Some plants only flower on the new wood the following season and you should only prune on very old rigid wood.



As for when is the best time to prune really depends on the type of plant/shrub/tree as some need to be pruned straight after flowering, some need to be pruned when they start winter hybernation and some should rarely be pruned at all. My best advise is buy a good book on the subject like the Royal Horticultural Society Encyclopedia of Gardening or another one I use is Pruning Basics by David Squire.
Reply:It usually means that the plant flowers only apear on either old or.new wood. Also the best time to prune if you are unsure is in the spring just as the buds are forming.