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By Bernard

Cambridgeshire, United Kingdom Gb

Buds in the offing. We have a pink rose aginst the front wall of our bungalow. Earlier this year it flowered profusely and I dead-headed it regularly. After a pause to recover it's strength it is now throwing out new very vigorous shoots, some of which are growing across the windows and I have been watching with great interest. The new stems are now over three feet long and at last new buds are forming at the tips of the the shoots. This has caused me to wonder what it is that triggers the production of buds and it would be lovely if someone could explain the process that switches the plant into bud production mode.



well are you sitting comfortably.... this may take some time.

there are several triggers from day length/light quality, temperature and plant hormones and they may all interacting.

The commonest is light quality [wavelength of the light]/day length, this triggers the production of plant hormones that then trigger cells to form buds. As you keep dead heading, the plant doesnt get another hormone produced from the developing seeds that supresses flowering in favour of seed production. So you get more flowers.
Temperature in some plants also triggers hormone production but I'm not certain about roses.

Hope this explains a very complex bit of biology.

25 Jul, 2011


To make it even more complicated, different types of roses respond to different combinations of cues. Most species roses, many old hybrids, some climbers, and some modern shrub roses form flower buds in declining hours of daylight (i.e., in fall) but won't open the buds until after a period of cold weather, and in increasing daylight. Most "everblooming" modern roses form buds after the hormones in the growing tip have indicated that a certain number of leaves have formed--in modern climbers, that number is pretty high in upright stems from the base, but not in the side stems from those. All of this is also dependent on the bush having enough energy from sunlight to be able to budget in flower production.

25 Jul, 2011


My goodness, a simple question that prompted complicated answers! I'm much obliged to you both for taking the trouble to explain the astonishingly complicated processes that dictate the behaviour of the plants.

26 Jul, 2011


Complex indeed, and even those far more expert than us really don't understand it all!

27 Jul, 2011

How do I say thanks?

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