Q.Shrubs not forming many flower buds
I have two rhododendrons, two azaleas and a magnolia Susan, all planted in large planters (80l+). They all flowered to some degree this year; however, the magnolia only produced a handful of flowers at differing times, i.e. not all at once, and never more than 4-5 at a go. The azaleas bloomed moderately, but nowhere near as prolific as when I bought the plants during flowering the year before, and the two rhododendrons had significantly less and sparse flowers than when I bought them the year before. I bought one large rhododendron during flowering and the plant was covered every inch in blooms. This year I had about nine, compared to probably 40-50 when I bought it, and they were all on one area of the bush.
They have all shown signs of strong leaf growth since flowering has finished and are growing upwards powerfully, but the flower display on all my plants was very disappointing. What could have been responsible for poor flower bud formation? They were previously in a courtyard garden with not a great deal of constant sun, they were well watered and I added growth and bloom fertilizers to them a few times. Did I over fertilize? Over water? Not enough sun? What would you recommend I make sure to do this year so that they flower better next year?
You have touched on all the aspects of care of these shrubs that you will need to check against the recommended care requirements.
These articles will help you!
https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/rhododendron-care.htm
https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/rhododendron-not-blooming.htm
https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/fertilizing-rhododendrons.htm
https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/rhododendron-care.htm
https://www.gardeningknowhow.com/ornamental/shrubs/azalea/azaleas-noteworthy-shrubs-for-any-garden.htm
https://www.gardeningknowhow.com/ornamental/shrubs/azalea/fertilizer-for-azaleas.htm
https://www.gardeningknowhow.com/ornamental/shrubs/azalea/azalea-plants-in-pots.htm
https://www.gardeningknowhow.com/ornamental/trees/magnolia/sweetbay-magnolia-care.htm