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.
Azaleas are beautiful flowering shrubs that can add vibrant colors to any garden. Their stunning blooms come in a wide range of hues from white pink red, orange, purple and more. Azaleas belong to the Rhododendron genus and there are over 10,000 cultivars available.
If you want to grow healthy azaleas that bloom abundantly in your garden it’s important to understand their growth cycle. Azaleas go through different stages of growth and having knowledge about these stages will help you provide optimal care. In this article we’ll explore the different stages of azalea plant growth in detail.
Stage 1: Germination
The first stage of growth for azaleas is germination. This occurs when the seed starts to sprout and form roots. For the seed to germinate successfully, it needs a warm and moist environment. The ideal temperature range is 65-75°F.
Azalea seeds can be started indoors in flats or pots. Cover the seeds lightly with soil and keep them moist until sprouts emerge. This usually takes 1-2 months. Once the seedlings have 2-3 sets of true leaves, they can be transplanted outside after the last spring frost.
Stage 2: Vegetative Growth
After germination, azalea seedlings enter the vegetative growth phase This is when the plant focuses on producing stems, leaves, and branches to establish itself With proper care, which includes sufficient water, nutrients, and sunlight, the young plant will grow rapidly during this stage.
To encourage bushy growth, it helps to pinch out the topmost part of the main stem. This causes the plant to branch out from the lateral buds. Regular pruning and trimming also promotes density.
Stage 3: Bud Formation
In the third stage, vegetative growth slows as the azalea plant starts forming flower buds at the tips of branches. This usually occurs in late summer or fall.
As the buds develop, it’s important to ensure the plant isn’t stressed. Factors like drought, extreme heat, pruning at the wrong time can all lead to loss of flower buds. Proper care and avoiding these stresses result in a profusion of blooms in spring.
Stage 4: Flowering
This is the most spectacular and colorful stage of azaleas. Depending on the variety, blooming occurs in spring or early summer. Flowers come in diverse sizes, forms and hues. Large-flowered types like the Belgian Indica hybrids put on a striking floral display.
During this stage, deadhead spent blooms to encourage repeat flowering. Water generously when the soil feels slightly dry. Mist the foliage occasionally to increase humidity.
Stage 5: Fruiting
Not all azalea varieties produce fruit, but some do after flowering. The fruits take the form of woody seed pods that hold numerous tiny seeds. Each pod splits open when ripe to release the seeds.
If you want to collect azalea seeds for propagation, harvest the pods as soon as they split. Store seeds in a cool, dry place. Remove spent blooms and seed pods to neaten up the plant.
Stage 6: Dormancy
After fruiting, azaleas enter a dormant period as temperatures drop and daylight decreases. Growth slows down and the plants prepare for winter.
To help them cope with cold weather, add a thick layer of mulch around the base. Prune branches to remove deadwood and shape the plant. Avoid heavy pruning that can stimulate growth which is detrimental going into dormancy.
Caring for Azaleas in Each Stage
-
Germination: Keep seeds moist and warm. Transplant seedlings when they are few inches tall.
-
Vegetative growth: Water regularly and fertilize every 2-4 weeks. Pinch out tips to encourage bushy form.
-
Bud formation: Avoid stress and extreme weather. Shading plants if needed.
-
Flowering: Water when top inch of soil is dry. Deadhead spent blooms. Mist foliage.
-
Fruiting: Harvest seed pods when dry and split. Remove spent blooms and seeds pods.
-
Dormancy: Add winter mulch. Prune lightly to remove deadwood.
Factors Affecting Growth
Several factors can impact azalea growth patterns and transition through the various stages:
-
Climate – Azaleas thrive in mild weather and cool nighttime temperatures. Hot and cold extremes can stress plants.
-
Sun exposure – Most azaleas grow best in light afternoon shade. Too much sun can cause leaf scorch.
-
Soil – Azaleas need rich, acidic, well-drained soil to grow their best. Heavy or alkaline soils can be problematic.
-
Pruning and deadheading – This encourages new growth and blooms but should be avoided when plants are entering dormancy.
-
Nutrition – Regular feeding with fertilizer supports growth and flowering. Soil should also be tested for correct pH.
-
Moisture – Azaleas need frequent watering but soil should drain well to prevent root rot. Mulch helps maintain soil moisture.
-
Diseases and pests – Prevent and control diseases and pests to avoid damage, dieback or plant death.
By understanding what happens during each stage of growth, you can time your care accordingly and help your azaleas put on their best performance. Pay close attention to their needs at every phase and you’ll be rewarded with lush green foliage and abundant blooms in the garden.
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.
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.
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.
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.
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.
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.