All About Hydrangeas
Hydrangeas are the most popular summer-flowering shrub. Their large, colorful flowers offer outstanding interest spring through fall, and pair nicely with perennials and evergreens.
English Gardens carries nearly 50 varieties – there’s one that’s bound to fit perfectly in your garden.
Hydrangeas do best planted in areas with sun or partial sun, planted in consistently moist, well-drained, organic-rich soil. Too much shade can result in reduced bloom production. When planting hydrangeas, enrich the soil with top soil and peat moss for welldrained soils, or top soil and soil conditioner for poorly drained or clay-based soil. Also add Espoma Bio-Tone Plant Starter to encourage rapid root growth. Applying a two to three-inch layer of mulch will help keep roots cool and retain moisture during dry summers. Also deep watering every couple of days, or as needed, for newly planted hydrangeas and established hydrangeas is recommended, especially in dry weather.
Fertilize established hydrangeas with Espoma’s Plant Tone every spring.
The two most common questions we’re asked? How do I get my hydrangeas to change color? Why aren’t my hydrangeas blooming?
How to Change the Color of Hydrangea Blooms
Any of the macrophylla (big leaf hydrangea) or serrate (mountain hydrangea) have the ability to change bloom color. Bloom colors range from blue to pink and all the shades in between, depending on the pH of the soil. pH is a measure of how acidic or alkaline the soil is. Low pH, below a 7 on a scale from 0 to 14, will produce blooms in the blue range. Soils with a high pH, above 7, will produce blooms in the pink range.
A soil test is the best way to determine what the soil pH is. Testing is available at English Gardens.
The availability of aluminum in the soil, and soil pH below 6, helps make the blooms blue. Depending on the existing pH, apply Espoma Soil Acidifier or Aluminum Sulfate every month to achieve the desired shade of blue.
Add garden lime to increase soil alkalinity and turn blooms pink. Color may vary from season to season due to weather, plant stress and changes in the environment. Plants near a concrete foundation or walkway may never turn blue because of the lime that leaches out of the concrete.
Altering your soil to change a hydrangea’s color is not a one-time thing. You’ll have to continually add minerals to maintain the altered soil conditions.
Why aren’t my hydrangeas blooming?
There are four common reasons why hydrangeas fail to bloom:
- Improper pruning. See information below.
- Planting in the wrong place, or planting varieties that bloom on old wood in areas that are too exposed to severe winter weather will typically result in little to no flowers. These should be re-located to a better site or protected through the winter. A shrub guard or burlap wrap filled with leaves to help insulate stems is recommended.
- A late spring freeze or frost ruins flower buds.The freeze may be light and even go unnoticed until you realize no blooms are forming. Or the frost may damage emerging leaves, too. As a result, most of the new growth comes from the base of the plant, not the stems, and no flowers will form.
- Deer browsing. If hydrangeas are growing in a place where deer are present, they will typically eat the flower buds and you’ll never see flowers. You might not realize that deer are a problem, until the hydrangeas don’t bloom, especially if you have some that are blooming in a different location. Prevent deer browsing by applying repellents as new leaves begin emerging in the spring, and every few weeks thereafter.
One of the critical factors for successful hydrangea bloom is when and how to prune. The key factor is whether the plant blooms on new or old wood. Do the blooms develop on this season’s new growth or last year’s mature stalks? It is always best to choose a plant that fits the space it will occupy. That way, pruning can be kept to a minimum and done only for the well being of the plant and to promote vigorous flowering.
There are five types of hydrangeas, which fall into two pruning groups.
Group I, generally, bloom on old wood. These plants produce flower buds on stems from August through October for the following summer’s blooms. If these stems are pruned in the fall, winter, or spring, the bloom buds will be removed, and there will be little or no bloom the following summer. Types in this group are:
- Hydrangea macrophylla (mophead and lacecap)Big Daddy, Homigo, Lemon Daddy, Nikko Blue, Pia, or Pistachio
- Hydrangea quercifolia (Oakleaf) Alice, Munchkin, Sikes Dwarf, Snow Queen
Group II bloom on new wood. These plants produce flower buds in the current season, beginning about a month or two before they bloom. Therefore, they can be pruned any time after they bloom and up until they begin producing flower buds. Types in this group are:
- Hydrangea arborescens (smooth hydrangea) Annabelle, Bella Anna, Invincibelle Spirit, Incrediball.
- Hydrangea paniculata (PeeGee and family) Bobo, Bombshell, Fire & Ice, Limelight, Little Lime, Phantom, Pinky Winky, Quick Fire, Sweet Summer, Vanilla Strawberry.
- Hydrangea anomala petiolaris (climbing hydrangea)
- The everblooming varieties of Hydrangea macrophylla also belong to Group II and include Forever & Ever Hydrangea Series and Endless Summer Series.
If in doubt, only prune off old flower heads and leave the rest until spring. Once June arrives, you’re safe to prune off any stems that have not produced leaves.