Hydrangeas perform well in the St. Louis area and the choices can be overwhelming. Hydrangeas range in height from varieties like Wee White and Bobo ( 1- 3 ft. tall) to Limelight and Firelight ( 6-8 ft. tall). With the wide selection of colors and heights, there’s sure to be a hydrangea that will suit your garden. The smaller selections are great in the garden or even in pots. These can be brought up close to the house, mulched and over wintered just fine. The larger plants make colorful privacy hedges.
Big-Leaf or Mophead Hydrangeas
- Large leaves with mop type flowers
- No need to prune unless to control height
- If pruning is necessary , do so after the plant has bloomed during the summer not in the spring
Smooth or Annabelle Hydrangeas
- Annabelle is the original and still a popular old- fashion favorite
- Invincibelle is an improved series of Annabelle hydrangeas that rebloom
- These plants bloom on new wood so they can be pruned whenever it’s convenient
Panicle or Peegee Hydrangeas
- Cone shaped or conical flowers
- Can tolerate more sun than other hydrangeas
- Blooms on new wood each year so can be pruned whenever it’s convenient
- Attractive large oakleaf shaped leaves turn reddish maroon in the fall
- Exfoliating rough bark is interesting all winter
- Blooms on old wood so do not prune unless needed to control height and then right after flowering
Why Didn’t My Hydrangea Bloom?
We get this question frequently and there are a few reasons. This quick video sums up the main reasons, including age of the plant, amount of sunlight, pruning, deer and late frosts.
Flower Color- Blue Verses Pink
All hydrangeas undergo some color change as their flowers mature, but only the bigleaf or mophead varieties can be manipulated from blue to pink or from pink to blue. Blue flowers are the result of a low ph or acidic soil, whereas pink flowers occur in high ph or basic soils.
Hydrangeas in our area tend towards pink. Getting them to bloom blue requires soil amendment. We prefer Espoma’s Organic Soil Acidifier, which with time, will safely and effectively produce bluish flowers. You must apply the acidic feed on a regular basis, once a month during the active growing season, to maintain blue blossoms.
General Growing Tips
- Plant hydrangeas in moist, but well-drained soil.
- Contrary to popular knowledge, most hydrangeas benefit from some morning or late afternoon sun.
- The panicle hydrangeas, like Bobo and Limelight can tolerate the most sun but should be well mulched to maintain moisture and a cooler root environment.
- Hydrangeas have shallow roots, so they dry out quickly. Watch carefully during periods of high temperatures and/or drought.
- 2-3 inches of mulch benefits all hydrangeas when the summer approaches.