Weigela ‘Sonic Bloom’ Failure to Thrive


We planted a sonic bloom weigela (which came in a 8inch pot) 3 years ago and after its 1st winter it turned brown and the branches were mostly done. Then it sprouted a little bit in early summer and it grew very little with 1 or 2 flowers so we kept it until the next summer. Then it grew just a little before fall. This year it began life again in spring and then we gave it 10-15-10 liquid plant food fertilizer and it responded. We have been giving it fertilizer every 6 weeks and it has shown a little growth and its only leaves with no flowers.
Please advise what I can do to get the weigela to blossom with flowers and reach full growth by next year.


Sorry to say I don’t have a definitive answer to assure your plant will be a thriving specimen  next year.  Variety Sonic Bloom has been around for almost a decade and the literature suggests it does well as a rule.  The  horticultural company that has registered this variety, has no mention of major problems for Sonic Bloom on its website.   The company suggests it should grow at least one foot ( 30cm) a year.  Proven Winners  By your description it has never achieved this rate.

Weigela are deciduous shrubs: that is their leaves turn brown and fall off in the fall.  Usually the rapid phase of growth ie the lengthening of branches and the proliferation of leaves, happen in the cooler periods of spring and again in the fall.  They don’t grow much when it is hot.  The plant sets it’s flower buds in the fall, so if the winter is harsh and the plant exposed to north wind, the plant will not likely flower profusely in the spring. Also the branches will have what is called ‘die back’ where several inches of the end of the branches die off.   Last winter we had a warmer Jan/Feb but the last part of Feb was cold and blustery and it is possible that the buds on your plant were desiccated by the cold resulting in few if any flowers.Winter Kill  But this does not explain the failure to grow significantly in the last three years.

Here are some points about how the environment affects Weigela shrubs Weigela Care  Please consider these when you next look at your plant.  In summery, Weigela like well drained soil ie something that you can dig in without too much effort. Is your soil clay and puddles form after a rain storm?  Do you have a sprinkler system that overwaters?

They like sun and also do well in part shade. But if the shrub is under a large old tree facing north, maybe it needs more sun and the tree is stealing all the moisture and nutrients?

Because weigela prosper in soil that has average fertility, they can be injured by excessive fertilizer.   I would consider your use of fertilizer every six weeks to be excessive for this plant.  Nevertheless your email indicates that in other years you did not do this.  If you decide to keep your plant, I would suggest rather than chemical fertilizer you add 3-4 in (10 cm) of compost, or a mixture of manure and compost once a year in spring or fall around the base of the plant (not covering the base of the main stems) out to the drip line.

Finally what you describe doesn’t sound like a disease but it is possible that your shrub is diseased.  Weigla is suseptable to a serious fungal disease called Verticillium Wilt (VW). VW One way to identify this fungus is to look for “a scorched appearance” on leaf margins.  This fungus hangs around from year to year weakening the shrub which finally succumbs to the disease or to other diseases.  You can ask a reputable nursery for a fungal spray but VW is seldom cured only controlled with difficulty by proper care of your plant as described above.  If you decide that your plant has VW I would remove it and discard it in the garbage not the compost.  And don’t plant a shrub susceptible to VW in the same spot.  Best of luck.

September 18, 2021