Why do some woody plants grow on "new wood" and some on "old wood"??

Question

what does this neccesarily mean, and how does it work?

if you dont cut back the ones that grow off of new wood what happens?

thanks for your answers!

Answer 1

It's genetics.

If you have blooming plants that bloom only on the new, fresh wood, (like some types of Hydrangea) & you don't cut off the new wood (new growth)... they will bloom when they are supposed to.

However, if you cut back the "new wood" that contains the flower buds of these particular plants .... then they won't bloom.

New wood, young wood, or current year's growth are all generally accepted terms to mean the same thing.

"Some plants, including many shrub roses, viburnums, buddleia and hydrangeas, will flower this season on twigs that developed this spring. They are “flowering on new wood.” Other plants, such as forsythia, lilacs, mockorange, rhododendrons and azaleas, flower on stems that grew last year or earlier. Plants that flower on “old wood” may not bloom after an especially hard winter if the twigs or flower buds were damaged. Also, if these plants are cut back too late in the year, the buds for next year have been cut off, and there will be no flowers. These plants are best pruned each year just after they flower."
http://www.bachmans.com/WeeklyUpdates2002/07_03_02.cfm
Good Luck! Hope this helps.

Answer 2

New wood means this years growth. Old wood is anything other than this years wood. Some plants only get flowers on the new wood. If you cut off the new wood you wont have any flowers. This is not true of all plants, so check your specific plant before you prune. There are tons of sites on the web to help you out. Good luck.

Answer 3

The reason is simply that those plants that flower in winter or early spring will not have any time to grow any new wood, thus they have to flower on wood grown in the previous growing season. Woody plants and climbers that flower later in the year, have had plenty of time to grow new wood, and thus it is on this that they flower.
Plants that flower on the current season's growth do not flower on the previous season's growth, so if you just leave them, they become very woody, with just the flowers on the ends of branches.
The simple rule is this:

If it flowers in spring prune after flowering; if it flowers later in the year prune in February (in the UK)

Answer 4

I have no clue what you are talking about, do you mean why do some trees if you cut them down do not grow back like White pines? but if you cut a redwood tree down it will grow from sprouts? it must be the way they store energy in their roots

Answer 5

I am not a gardener but I love my garden.
Every year I am told to trim back my hydranger to allow new groth. I never have and my blooms are larger and more abundant than theirs.