Why is this...?

'As the growing season progresses, a plant’s response to pruning changes, with its response becoming less vigorous after the midpoint of summer.'

The Royal Horticultural Society. RHS Botany for Gardeners: The Art and Science of Gardening Explained & Explored (p. 163)


Could anyone explain to me why this is? I would have assumed the response would have been the same until the beginning of colder weather

 

Presumably because the initial rush of sap rising slows down after spring and new growth slows.
Leaves turn darker green and get tougher.
Most plants have pretty much got seasonal growth in their genes, its part of their make up, well hardy plants anyway.

 

Plants are very clever,they know to ease off best part of the way through their growing year so as not to succumb to the winter perils.

 

Depends on the plants too...don’t forget we grow plants from all over the world and they all respond accordingly.
For example, aeoniums do most of their growing in the cooler autumn and winter months

 

Day length has a lot to do with it. As the days shorten after midsummer the plant begins to prepare for winter and the next spring so for example flower buds begin to form, bulbs (onions are a good example) and tubers begin to swell.

 

Some great answers there thanks!

 

So say i were to prune hard something deciduous, say cotinus for example, without waiting until dormancy. The plant detects the longer nights towards the back end of summer and slows growth to instead focus on replenishing its energy stores to prepare for autumn/winter. Would I be causing it harm as i'm cutting away its ability to photosynthesise right at the point were it had already used most of its energy reserves and needed to produce and reserve them? (Plus any stored energy in the leaves would now be wasted)

All the guidelines say to wait until the majority of deciduous plants are dormant before pruning hard and i'm beginning to understand why, but in practice a lot of plants seems to bounce back anyway, whats going on within the plant when this happens?

 

@Mondomondo

Tread carefully all shrubs are different as @Verdun said they come from all round the world. pruning is often done after a shrub has flowered or fruited eg philadelphus, deutzia, rubus or when they are dormant. Others are pruned after the winter as the new growth might be damaged by frost.
Having said that you would probably get away with it, I would always look up advice for the particular shrub if I wasn't sure.
Cotinus is something that needs little pruning, normally, removing dead, diseased, crossing branches and branches growing the wrong way.