Introduction
Azaleas, also known as genus rhododendron, are a wonderfully diverse and hardy shrub that brings beauty to your springtime garden. Typically blooming in early spring, their flowers are a stunning array of color. There are dozens of varieties, which offer colors from fluorescent pinks and purples, to whites, yellows, and even oranges. Azalea plants are some of our favorites, and this guide will walk you through how to care for them, whether you’re a beginner gardener or a master. Keep reading for the essential care tips to help these stunning shrubs thrive.
With some of the brightest and early-blooming flower buds around, you’re sure to enjoy an azalea shrub in your yard.
Choosing the Right Azaleas
Azaleas are part of the rhododendron species, botanical name rhododendron spp. Within the genus there are hundreds of types of azaleas, which mostly fall into two categories: deciduous azalea and evergreen azalea. Evergreen azaleas, like our P.J.M. Rhododendron, keep their leaves and provide color year-round. Deciduous azaleas will drop their leaves in fall and grow them anew come spring. Because of this, deciduous azaleas are naturally more hardy and can tolerate colder weather.
Different azalea varieties will vary in size, so make sure you choose a variety that will fit the space you have. A mature azalea typically grows between 4-6’ wide x 4-6’ tall. Compact or dwarf varieties, like our Compact Korean Azalea, have a mature size of 2-4’ wide x 2-4’ tall. Smaller varieties can make great hedges or mass-plantings due to their dense growing habit. Plant azaleas where they have adequate space to show off their wonderful flower buds.
Another factor to consider when choosing azaleas is to choose an area with partial shade. Azaleas grow best in part sun, and can tolerate morning sun with afternoon shade. They also appreciate a dappled sunlit area throughout the day.
Do you know your growing zone? All plants have zones they thrive in, and azaleas are no different. The two varieties we offer are best for zones 4-8, but other varieties, especially some evergreen ones, are susceptible to winter damage, so zones 6-9 are ideal. When researching azaleas, make sure to choose one suitable to your climate as well as your tastes. If you’d like to get some local advice regarding your growing zone, we recommend reaching out to your local college to see if they have a horticulture program. Many state colleges have extensions with horticulture resources. In Wisconsin, UW-Madison Extension can provide helpful advice.
Most azaleas prefer acidic soil, rich with good drainage. If you’re unsure about the pH of your soil, we recommend using a pH tester, specific to soil. This will help you determine if any additives are needed to provide the necessary nutrients to grow azaleas, especially if your pH indicates you have alkaline soil. There are many options for additives that can be found at your local garden center, or contact us with any questions.
Planting Azaleas
Proper planting of azaleas plays a critical role in the health and longevity of the plant. Giving these flowering beauties their best start can set them up for years of strong growth and allow them to develop good disease resistance. That said, below are a few tips for planting azaleas.
Plant azaleas in either spring or fall. These seasons give plants the best start they need to thrive, due to cooler temperatures which puts less stress on the plants, increased moisture in the soil, and reduced disease and pest opportunity.
Prepare your planting site. As mentioned above, the azaleas prefer acidic soil with proper drainage. Make sure your pH is between 4.5 and 6.0 to grow azaleas properly. Amend your soil if needed to ensure plants receive adequate nutrients.
When you’re ready to plant, follow these steps:
- Slide the root ball from the pot by tapping on the bottom of the pot.
- With a shovel or knife, trim the bottom 2" off of the root ball.
- Rotate the plant to the proper position. Never lift or move plants by the tops.
- Place the root ball in the hole.
- Notice where the base of the trunk flairs out from the tree. This is called the root flair. This root flair should show when the tree is planted. If necessary, add soil under the ball so the root flair is exposed. Be careful not to plant too deep, as azaleas have shallow roots.
- Backfill the hole with soil, making sure the top of the root ball is visible and slightly higher than the soil around it.
- Firm the soil around the azalea. Water well to settle soil around the root ball. Nursery tip: water freshly planted azaleas deeply once per week to help establish healthy roots. Continue this practice for its first growing season.
- Mulch your newly planted azalea, but leave some space around the base of the plant.
Watering and Mulching
Good watering techniques will help azaleas bloom and grow to their fullest potential. For azalea plants in their first season, a weekly watering will help them to establish their shallow root system. After its first season, only water when necessary in a dry spell or drought. We recommend watering early in the day to reduce evaporation, allowing the water to reach the roots.
Be careful not to over or underwater azaleas, which can cause wilting or diseases like root rot. The easiest way to tell if your plant needs water is to touch the soil around the roots, up to 3” deep. If it’s moist, there is no need to water. If it’s dry, give it a good soaking with the hose end, watering the soil only, not the leaves.
If your plant’s leaves are wilting or turning yellow, this may be a sign of underwatering. If the azalea has unnaturally dark red or brown colored bark near the base, as well as wilting or discolored leaves, this could be a symptom of overwatering.
Mulch azaleas after planting. We recommend a 2-3” layer of organic mulch (shredded bark, pine needles, etc.) covering the drip line of the branches, but leaving some space around the stems. Mulch helps regulate soil temperatures, maintain moisture levels, and suppress weeds, making your job easier! Looking for more mulching tips? Check out our mulching guide.
Fertilizing Azaleas
Slightly acidic is the perfect soil azaleas can benefit from, so keeping an eye on your soil’s pH level is important for their care. If your balance is thrown off after planting, you can mix additives to the soil during spring and early summer. Avoid adding nutrients in fall, as it could trigger new growth and ultimately harm the plant in winter.
If you’re in the market for fertilizer, a local garden center or horticulture extension can provide guidance on proper ones for your variety of azalea. After applying, make sure to water thoroughly to distribute the nutrients evenly to the roots.
Pruning Azaleas
Azaleas bloom in early spring, and deadheading can tidy up your plant and help promote a rebloom. Deadheading also stimulates healthy growth and increases blooms the following year. Deadheading sounds scary, but it’s a beneficial process that removes spent flowers to breathe life into your flowering shrub all season long.
The best time to prune azaleas is immediately after they finish blooming. Azaleas form next year’s buds during mid to late summer, so pruning before they form is essential to shape the plant and encourage more flowers.
What parts of the shrub should you prune? Look for dead or diseased branches, spindly growth, or branches that rub against each other. Make the cut at a slight angle right above a leaf node. You can also thin our dense areas to improve air circulation and light penetration within the plant. Make sure your pruners are sharp and clean to avoid the spread of potential diseases.
Pest and Disease Management
There are several pests and diseases that can harm azaleas. Common pests like spider mites, lace bugs, aphids, and azalea bark scale can impact azalea health. Azaleas can become afflicted with diseases like azalea gall, leaf spot, powdery mildew, blight, and rust. Although not overly susceptible to any of these, deciduous azaleas tend to have a slightly higher chance of becoming infected.
They say prevention is the best medicine. In the case of potential pests and diseases affecting azaleas, this is certainly true. Some of the easiest ways to prevent diseases and pests is maintaining proper air circulation between plants through adequate spacing, keeping the area around the plant clean of debris to discourage bugs and insects, and avoiding watering the leaves of the plant to prevent leaf diseases.
If you suspect a disease or pest is affecting your azaleas, visit a local garden center or horticultural extensions for advice on natural and chemical control options. Neem oil can work great for some pests, and fungicides are available for diseases. Proper identification of the pest or disease is vital before you start any treatment.
Regularly inspect your plants for any troubling signs of distress, and act swiftly if you notice anything out of the ordinary.
Winter Care
The cold months of our northern states can be a difficult place to grow azaleas, but there are varieties that thrive here! Knowing your growing zone and choosing plants that can tolerate the fluctuating temperatures is vital to the plant’s success. Once you choose an azalea that’s tolerant of winter, consider the location in your yard. If you have harsh winters, you may want to plant azaleas in a sheltered area or consider windbreaks to protect against the elements.
Well-hydrated roots are able to withstand cooler temperatures, so make sure you water well before the first big freeze if you haven’t received adequate rainfall.
If you’re worried about your azaleas standing up to the freeze, you can apply a fresh layer of mulch after the first deep frost. This will help insulate the roots and regulate the soil temperature despite rapid outdoor temperature fluctuations.
To Sum It Up
For the spectacular springtime show, azaleas are one of our top picks. From their range of stunning flower colors to their diversity and range, these shrubs are crowd-pleasers. In this guide we covered all aspects of their care, how to choose and plant them, and pesky pests and diseases to watch out for.
For more planting tips, visit our Green Tips page.
