Hi, This bush was here when I moved in 10 years ago. It was lovely and full of flowers. As it was starting to encroach on the whole yard (small yard), I started pruning it. All seemed well until a few years ago when I noticed it was getting more sparse and had many dead branches. It flowered less. Strangely, new leaves were much larger than the earlier ones (see photo). Your advice would be so appreciated. Thanks so much!
Keeping older shrubs shapely can be a challenge, especially in the smaller garden. In terms of both shape and vigour, mature shrubs of all kinds benefit from the removal of older interior branches – this will allow light and air in, improving the overall health of the plant by increasing photosynthesis and helping to prevent fungal diseases.
Because Weigela blooms on the previous year’s growth, pruning in late spring, once flowering is over, is the best time to trim and shape your shrub. However, now may be a good time to prune away any obviously dead or damaged branches from the interior of your Weigela –before its leaves drop and while you can clearly see which branches are dead. This will give you a good framework to work with once blooming is finished next spring. Alongside pruning, you should also consider your soil: a layer of compost in the fall is always a good idea, especially if you have not done this in a while.
Here is a previous Toronto Master Gardeners post that gives good advice about pruning:
It is difficult to say for certain why the new leaf growth may be larger and more robust than earlier growth. Factors that influence leaf growth can include increased sunlight, optimal irrigation, soil amendment with compost, and pruning itself which can stimulate new and more vigorous leaf growth.