Cranberry viburnum not flowering

(Question)

Hi, I planted a cranberry bush (viburnum) 2 years ago. The plant is thriving and growing lots of healthy foliage as well as growing by several feet. The exposure is west and it gets lots of Sun. However, it shows no sign of budding. How long should I wait for the plant to establish? Or should it have flowered by now? Thank you!

(Answer)

Thank you for contacting the Toronto Master Gardeners.

Cranberry Viburnum, Viburnum Opulus, can be a striking addition to any garden, especially when it is loaded with blooms.

As you state the foliage and plant looks generally healthy, I wonder if you have over fed it. Plants getting an abundance of food will grow vegetatively, at the expense of blooming. This may happen due to a highly nutritious original soil, amendments like manure or compost being added at the time of planting, annual feeding to the garden bed or lawn fertilization with a high Nitrogen product.

Your plant could also just be settling into its new location by using its energy to grow branches, leaves and roots. Transplanting trees and shrubs can be quite stressful for the plant and sometimes it takes years before they live up to their flowering potential.

I would suggest you just keep it watered well in the hot summer months, as this will not only supply moisture to the plant, but will also flush some of the extra nutrients out of the soil, should an excess of nitrogen be the case. Also, do not be tempted to feed it now or in the spring as doing this could exacerbate your problem.

One last thought, do not cut it back now, as this will only cut out the flower buds for next year. Any pruning should be done straight after flowering — so leave it for this year.

Of note, this plant can be invasive under the right conditions, so watch for spread and if you are in an environmentally sensitive area, please be vigilant.

We hope this is helpful.