How To Care For and Prune Hydrangea Flower Shrubs
Expert tips on growing hydrangea flowering shrubs
I adore hydrangea flower shrubs. They are show stoppers in a yard or garden when they are in bloom, and the plants’ blooms you get to enjoy for a long time. So many varieties to choose from, so little time. Perhaps your hydrangea flower questions will be answered here.
Growing the many varieties of hydrangea flowering shrubs can yield stunning summer and fall flowers. Sometimes gardeners have questions about their care and getting them to flower. We’ll look at some of these common questions to help yours be the best they can be.
Here in the Pacific Northwest, we enjoy our hydrangeas. They may be the big mophead varieties that can grow in shades of blue, purple, pink, and white or the delicate lace cap varieties. There are more than 70 different types. I tend to like the big mophead types best.
Hydrangeas are beautiful dried or fresh and can be used in crafts, and cut flower bouquets. I’ll write more about drying them properly and making wreaths in another article.
Depending on the type, they may grow in full sun to full shade. Learn about the specific hydrangea’s needs for shade and sun before planting your variety, as their needs vary per species.
For ideal soil conditions, they all require rich compost and other organic matter, with well-drained soil.
How should I fertilize my hydrangea flowers?
Fertilizing shouldn’t be done on hydrangeas until after they’ve been planted at least three months following planting or transplanting.
If you do fertilize, do so sparingly since the plant will stop flowering if it receives too much nitrogen. The best time to apply a light fertilizer is in the early spring when it is just breaking dormancy.
A good fertilizer (I prefer using organic types), but find something that is a slow-release type, like a 10–10–10. That is an equal portion of potassium, nitrogen, and phosphorus. Apply to the soil around the base of the plant and gently work into the top layer of the soil. Water deeply at this point.
You could also skip a fertilizer, and instead apply a thick layer of rotted manure or compost and work gently into the top soil layer. This is a good idea to do in the fall as well.
PH Balance and Hydrangea Colors
The pH balance of the soil affects the color of the blooms. While some varieties are specifically grown to be certain colors, they can be heavily influenced on the color by the soil pH.
If you want a blue-colored hydrangea, the soil should be a bit on the acidic side, between 5.2–5.5.
Pink colored blossoms in hydrangea shrubs arrive that way in a more alkaline setting of 6.0–6.2.
Red hydrangeas are on the higher end of the 6.2–6.5 end of things.
Shades of purple hydrangeas will fall somewhere in the middle of 5.6 —5.9.
White hydrangea flowers should have a pH balance of about 6.0–6.2.
Using soil additives can get you the colors you would like. Using garden lime, or dolomite will help with the pink flowers.
For the blue colors, use aluminum sulfate or a safer alternative, iron sulfate. If you use aluminum sulfate, be sure to rotate the next year with iron sulfate. Apply at the rate recommended in the bag’s directions.
It will take time for the flowers to be affected by the change in soil pH, however, so give it time. It is best to apply in early spring and check again in early to mid-summer, adding a bit more if needed.
Sometimes, organic mulch will also affect the soil pH, so be sure to use a soil pH tester to keep an eye on it.
Product Recommendation: Soil Ph Meter, Soil Tester for Moisture, Light,Nutrients, pH Test kit
Why Doesn’t My Hydrangea Flower?
The problem of hydrangeas failing to flower can happen for a couple of reasons. Most commonly is frost damage by a late frost, or a harsh winter.
Incorrect pruning can also be a cause, unknowingly cutting off the blooms that would have blossomed. The bigleaf and oakleaf types of hydrangeas, bloom on old wood.
Too much nitrogen or over-fertilizing can also cause a lot of leaf growth and few to any blooms.
Under- or overwatering can also cause this problem. Hydrangea shrubs need to be kept moist consistently but not waterlogged.
Too much shade can be a factor for some varieties. Partial shade means more than four (more like six) hours of sunlight. Perhaps your plant needs to be transplanted.
Planting in a more sheltered spot may be useful.
Reasons for Pruning Hydrangeas
Let’s explore why you would need to prune these shrubs in the first place. Regrettably, many people do so to make them smaller-sized plants, which is not a good reason to prune a hydrangea shrub. Unless you’re growing it in a bonsai dish, you’re bound to lose that battle.
Hydrangeas should be pruned to improve the look and general outline shape, not to manage the size of the plant.
The full-grown hydrangea is a shrub that can’t be made into smaller bush. If a big leaf hydrangea is cut down, a year later it will re-grow in size, and all the more in the next season. They do grow large.
If you would like to keep them small in stature, substitute your large growing variety with one that is genetically designed to stay small.
Some short-sized hydrangea bush varieties worth considering are:
· Pink Elf
· Hornli
· Blue Deckle
· Diadem
· Involucrata Tama Azisai
· Harlequin
· Quercifolia PeeWee
· Serrata Shirofuji
· Blue Billow
· Pia
· Mathilda Gutges
· Hortensis Compacta
· Glowing Embers
· Tovelit
· Red Star
· Todi
· Trophy
· Miranda
· Amethyst
· Bottstein
· Enziadom
· Forever Pink
· Masja
· Blue Danube
Proper Pruning Techniques of Hydrangeas
The dilemma is that the big-leaf hydrangeas, Hydrangea macrophylla (the type that forms big round balls of flowers), form their blossom buds in the previous summer. If you prune them short they won’t bloom very much the following summertime.
Almost all the renowned types of blue mop-head varieties in blue, pink or white lace-cap hydrangeas produce their blossoms on old growth wood.
Not every hydrangea plant flowers on the second year’s growth, and this increases the confusion. The sturdy tree type ‘Pee Gee hydrangea’, ‘Hydrangea Paniculata Grandiflora’, flowers on new growth along with the white-flowering ‘Annabelle’ variety hydrangea.
There are also some varieties that blossom on both new and old growth to further muddy the waters. When considering pruning, try to research the specific variety of hydrangea that you have.
The big leaf hydrangeas, lace-caps and mop-heads, should to be pruned as follows: prune early in the year when the plant has begun to break dormancy. At this time of the season, you can discern which canes are alive as opposed to which ones are dead.
Start by eliminating all dead canes, cutting them right down to the ground.
When all dead canes are cut, look at what is remaining. If still you have many living stalks, many of them being over three years old, cut out a third of those, again to ground level. This will encourage fresh growth. If the plant is just not congested with alot of older stems, skip this part.
Tidy the shrub by removing any old flowers that remain on the plant from last year’s blooms. Take care to trim the smallest amount possible, basic deadheading. You could also deadhead these in the late fall carefully.
Cut leftover stalks back by working from the top down, stopping and making the cut just above the top of the first or second pair of buds you come to.
Using this technique, some canes will be cut little or not at all, although some will have living buds near the base of the plant. In that situation, you’ll end up taking away a considerable amount of that stalk.
Step back and examine the shrub. If you find one stem that is much taller than the rest of the canes, cut it to be in balance with the other stalks. If there are any curvy, fragile and spindly looking limbs, or some that trail on the ground, eliminate those.
Remember that any green buds you prune have the possibility to produce blossoms later in the summer. Would you like a tidier plant or more flowers? Bear in mind you can always cut those blossoms for bouquets, and tidy the plant later in the summertime.
Be sure to use sharp pruning shears when pruning, and sterilize your shears between pruning different plants, so any disease is not spread.
One method to disinfect your pruning shears is to dip the blades in a disinfectant solution of one part chlorine bleach to nine parts water or use 70 percent wood alcohol.
Dip each time in between every cut of diseased plants, or you risk spreading the disease. Do not allow those diseased canes to remain in the area, or it can also spread to other plants.
With proper care of your hydrangea shrubs, you will be rewarded with healthy, thriving flowers for many years to come.
Other tips for growing hydrangea shrubs
Hydrangeas grow in USDA growing zones three through 9, with some exceptions. The big-leaf varieties grow best in zones five through nine, and the panicle hydrangeas can handle the cold better, zones three through eight.
Hydrangeas are fairly disease and pest-resistant, but here are a few things to watch out for.
Aphids, slugs and spider mites are usually the biggest pests. Aphids and spider mites can be handled with insecticidal soap (many recipes exist to make your own as well), or bring in beneficial insects like ladybugs.
If spider mite infestation is severe, you might need to use a specific miticide.
Slugs and snails, are tough, all I can say on this is good luck. Living in the Pacific Northwest, they are like the state’s mascot. Many years, I have to say slugs 10, Val 0, slugs won.
Some people use beer traps, some just hand-pick them (I can’t stomach that personally), some use slug bait and others spread diatomaceous earth around the soil.
To reduce disease, keep the area below the hydrangea clean and free of debris. Once leaves fall in autumn, rake them up and get rid of them.
Growing hydrangea flower shrubs is easy, and they are usually low maintenance in care. They are gorgeous in bloom and always draw attention to your garden or yard.
I’d love to hear, do you have any hydrangeas growing? If so, what types or colors are they?
Thanks for reading!
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