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Azalea 'Kaempo Pink', Shrub

Bring Out the Best in Your Azaleas and Rhododendron

David Yost, Merrifield Plant Specialist

Summer is almost here, and our beautiful azaleas and rhododendron are done or almost done blooming. This is the perfect time to prune your plants to increase fullness, promote overall health, and encourage a beautiful bloom in the upcoming year. Azaleas and rhododendron both respond well to pruning, and if done right, the plants will produce more blooms in a concentrated form next year.

For many of us, pruning back our prized shrubs can be a daunting task. Before you begin, analyze your goals and objectives for the task. Most people prune to manage the shape and size of their shrubs. Here are a few simple tips to assist you in preparing your plants for a full and beautiful bloom next year.

The best time to prune is at the end of your plants’ bloom cycle. 

Rhododendron before pruning

Rhododendron after pruning

Your azaleas and rhododendron will set their buds for next year by the end of August. To avoid cutting off next year’s blooms, trim your plant soon after the current blooms fade. For most of us, this will be now or in the next couple of weeks. I recommend completing your pruning project by the fourth of July holiday.

The correct tools make a difference.

For the sake of the plant—and your hands—you will want to make sure that you have both hand pruners and a pruning saw. Hand pruners work well for limbs under ¾ inch in diameter. If you use your hand pruners on limbs larger than that, you run the risk of ruining your pruners and mangling the branches of your plant. For the best results, switch to your pruning saw for all branches over ¾ inch in diameter. Also, before you begin pruning, clean your pruners and pruning saw with rubbing alcohol to ensure they are free of any contaminants that may harm your shrubs.

Prioritize dead branches for removal.

Before you begin shaping your plant, check it for dead branches. Unhealthy branches pose a risk to your plant’s overall health by increasing its exposure to infection and bugs. Dead branches will have no living leaves or new growth. It’s best to remove these first. Use your pruners or pruning saw to remove any dead branches, and remember to clean your pruners before moving on to complete additional pruning on your plant.

After you remove the dead branches, prune away overgrown branches to bring the plant to the size and shape you wish to achieve. Cut just above the node where branches separate with your hand pruners.

Beware of over trimming rhododendron. 

Azaleas respond well to pruning and even thrive with a major trim, provided you prune the plant before it sets its buds for next year. If your azalea is overgrown and needs a significant pruning, you can continue trimming branches as far down the plant as needed.

Rhododendron, however, prefer a light pruning rather than a heavy trimming. Remove dead blooms from your rhododendron plant, then prune lightly, using selective thinning to lightly prune the plant. If your rhododendron is overgrown, you can remove half the stems from the next older layer of the plant (below the one you just pruned). Save the second half for the following year. If your rhododendron are very overgrown, it may take a few years to prune your plants to a desirable height.

For even better blooms next year fertilize your plant after pruning.

After pruning I recommend fertilizing your plant to promote growth and increased blooms next year. You can use the Merrifield Flowering Plant Food or Holly Tone if you’re looking for an organic option.

Understand common issues and how to treat them.

When your azalea plant blooms during damp, rainy weather it may suffer from a common, but preventable, fungal infection: Ovulinia petal blight. If dead blooms remain on your azalea when you begin pruning, this fungal infection is the cause. To enable the blooms to fall off the plant before the bloom cycle ends and extend the bloom time of your plant next year, try spraying your plant with fungicide just before the bloom cycle begins next year. We recommend using Bonide Infuse.

Another common problem is caused by tiny insects called lace bugs. These critters may feed on your azaleas and rhododendron during the summer months. You’ll know if you have a lace bug problem as they suck the sap and bleach the color from your foliage causing the leaves to turn a yellowish-white color. You can also see these tiny bugs on the underside of the leaf if you flip the leaf over.

I recommend using Bayer Advanced Tree & Shrub Protect & Feed to treat these bugs if you encounter them. This product is a systemic drench control product that you put into the soil for the plant to absorb through the roots. One application will last all season. Apply this about once every three years to keep the lace bugs under control.

Celebrate Earth Day & Arbor Day

Michael Fahey, Merrifield Plant Specialist and ISA Certified Arborist

Every year we get excited about Earth Day and Arbor Day. These holidays mark two special days when the entire country comes together to celebrate and protect our natural resources. We encourage you to celebrate by embarking on a planting project with your family and friends. This year we’re celebrating a few of our favorite spring trees and shrubs that grow extremely well in our Northern Virginia area.

By planting trees and shrubs, you are cleaning the air, creating a habitat and food source for local wildlife and increase the value of your home. Not to mention, the act of planting itself is a big stress reliever! Head outside this week and plant a tree or shrub in honor of these two holidays.

Blueberries

You can have the sweet taste of blueberries right in your backyard by planting a native blueberry shrub. Blueberries are one of the biggest nutritional powerhouse fruits, providing anti-aging, cancer and disease fighting antioxidants. Luckily, these tasty shrubs prefer acidic soils, which makes them well-suited to Northern Virginia. They make a great addition to the garden as accent shrubs or even screening plants. The birds love blueberries just as much as we do. Protect your fruit by draping a large piece of bird netting over the shrub or using a large tomato cage.

Virginia Fringe Tree

Fringe trees produce panicles of airy, white, fragrant flowers that hang off its branches. This Virginia native produces beautiful blooms from late spring to early summer. To keep your Virginia fringe tree looking its best, plant it in moist, fertile, well-drained soil in part-sun to full-sun. The female versions of this tree will produce bluish-black fruits that attract birds. This tree is very easy to care for and makes a great addition to urban spaces as it tolerates some air pollution and is drought tolerant.

Serviceberry

Serviceberry is a standout native tree that provides four season interest to the garden. It produces beautiful billows of lacey white flowers against bright green foliage in the spring, tasty dark blue berries that our feathered friends enjoy in the summer, standout foliage in shades of red and orange in the fall, and silvery bark in the winter. Serviceberry is very versatile in the landscape as it is drought tolerant and happy in an array of sun conditions. Also known as Juneberry, people often use the fruit to make jams and pies.

Oaks

The oak tree family is abundant with many different species with varying heights and leaf shapes. Oaks are most beloved for their ability to provide shade in the landscape and standout color in the fall. Here are a few of my favorites:

  • White oak: Our national tree, the white oak is beautiful and majestic and feeds more wildlife than any other tree in the country.
  • Willow oaks: Its narrow leaf structure provides dappled light instead of dense shade. This fast-growing oak also thrives in wet soil.
  • Northern red oak: These oaks produce the most stunning, deep crimson fall color.
  • Bur oak: Part of the white oak family, the bur oak is pollution tolerant and has a sprawling growth habit and corky bark. This is a favorite for areas near a pond as it attracts wood ducks.
  • Saw tooth oak: This fast-growing oak has a unique leaf shape, interesting acorn and bark texture.
  • Columnar oaks: These reliable oaks are a great way to add trees to small spaces. A few of my favorites include ‘Regal Prince,’ ‘Kindred Spirit,’ and ‘Green Pillar.’

Azaleas

Azaleas are one of the most popular shrubs in our area due to their ability to produce funnel-shaped flowers in an array of vibrant colors in spring. Lucky for us, azaleas thrive in acidic soils, making them a great evergreen and flowering shrub in Northern Virginia. To keep your azaleas performing their best year-after-year, prune them once the blossoms fade, but before the new blossom buds appear. You can also thin out vigorous, over grown branches to stimulate new growth from the interior of the plants. Fertilize with Merrifield Flowering Plant Food or Holly-tone to support healthy growth and flowering for next year.

Rhododendrons

Spectacular clusters of bright, bell-shaped blooms and bright green, large, leathery leaves that remain on the shrub year-round make rhododendron a standout shrub choice in our area. Rhododendron come in a variety of bloom colors and sizes and will produce flowers for weeks. They prefer moist, well-drained, acidic soil and make great additions as foundation plants, woodland plantings or border plants in sunny to partly shady locations.

Camellias

We love camellias for their ability to provide exquisite blooms in single, double and full peony form when not much else is flowering in the garden. Plus, their glossy foliage is evergreen! These surprisingly low maintenance shrubs come in many forms and range in bloom color from soft pink to dark red to white. These beauties thrive when planted in acidic soil, making them a great choice for a mixed shrub bed, specimen plant or screening plant in Northern Virginia. Camellias are deer resistant and prefer to be protected from the hot afternoon sun.

Japanese Maples

The show stopping color a Japanese maple adds to the autumn garden is unmatched! These beautiful trees add instant grace and beauty to the landscape with their delicate leaf structures and vibrant colors that turn to shades of crimson, gold and orange in the fall. Japanese maples come in a variety of forms and leaf shapes, making them a great addition to your landscape as a specimen plant or focal point in a mixed bed.

This elegant tree provides a beautiful canopy of color that offers dappled light to understudy plantings, making it a great companion for shade perennials. Japanese maples are heavy organic feeders. Before planting, work compost or other organic matter directly into the ground. To keep your Japanese maple looking its best, plant it in well-drained, acidic, moist soil.

Kwanzan Cherry Tree

The Kwanzan cherry tree produces an abundance of stunning deep pink, layered, rose-like flowers from mid-April through May. Its new foliage emerges reddish copper in the spring, turns a dark green in the summer, and transitions to yellow, orange or bronze in the fall. Its upright, vase shaped form make it a great choice for a specimen tree or for lining a walkway, road or driveway. Plant your Kwanzan cherry tree in full sun conditions in acidic, well-drained, moist soil. The Kwanzan cherry tree does not produce any fruit, making it an excellent choice for a low-maintenance garden.

Pieris Japonica

Also known as lily-of-the-valley bush, pieris japonica is a dense evergreen shrub that produces drooping clusters of bell-shaped white flowers in early spring. Its foliage emerges orange-bronze but turns a deep, glossy green when mature. Pieris japonica makes a great foundation shrub or border plant and looks great paired with other acidic soil loving plants, such as azaleas, rhododendrons and camellias.  Plant pieris japonica in organically rich, well-drained, acidic soil in full sun to part shade conditions.

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