I have three weigela’s they get full sun from 1pm till 6pm. It is very hot sun. Last fall I trimmed them just about an inching on some branches. I covered them with mulch about 1 to 2 inches. One is got only 4 new branches that leafed out from the centre and the branches all around look dead, the other two have no sign of new growth. Would it be safe to trim them down in June since nothing is showing flowers or growth?
Thank you for contacting the Toronto Master Gardeners.
Sorry to hear about your ailing Weigela florida. Weigela florida is a hardy bushy deciduous shrub native to eastern Asian countries. It is a shrub that is tremendously popular in the garden because of its ease of cultivation and its abundant and long-lasting floral display throughout the summer. It prefers a sunny location and rich well-drained soil to perform optimally. However, it can survive in partial-shade and adapt to a variety of soils.
It is difficult to say what is causing your shrub to fail, however with the addition of organic compost and proper pruning practices you should start to see improvement. Amending the soil with some yearly compost will help, not only with moisture retention but also by giving the roots good nutrition. Similarly, adding a thin layer of mulch around the area will reduce water evaporation.
Because Weigelas flower on previous years growth pruning should be carried out immediately after flowering. I would begin by pruning out all the dead wood. With clean, sharp secateurs your aim is to start pruning from the inside of the bush, working your way out, removing dead/damaged wood, and thin out dense growth areas inside the base, to promote good air circulation. When pruning any large shrub use the measure of “one third” as a maximum amount of plant material you remove.
From your photo it appears as if your shrub is planted close to a wall. Do you have it planted in a narrow planting bed? Where you have the plant situated could be a factor is it’s poor performance. This particular species of Weigela can reach a mature height of 6-9′ tall and 9-12′ wide. As an alternative you might consider some of the more miniature varieties such as ‘minuet’ & ‘variegata nana’.