- Selecting Your Azalea Varieties
- Providing Azaleas With Proper Soil
- Watering Your Azaleas Properly
- Protecting Azaleas From Insects and Diseases
- Feeding Your Azaleas the Best Fertilizer
Thanks to modern plant breeders, azaleas aren't just for southern and coastal gardeners any more. Gardeners across the United States can enjoy beautiful azaleas by selecting the right plants from the start. In choosing the best azaleas for your garden, keep the following considerations in mind:
- Growing zone. Flower buds on spring-blooming azaleas form long before winter. Choosing types that withstand your winter temperatures is essential to spring blooms. Many azaleas are only bud-hardy in the country's southern half, but some northern-bred types can withstand minus 45 degrees Fahrenheit.1 Your county extension agent can help with zone information and tips on plants that will thrive.
- Light conditions. Azaleas are often considered shade plants, but many varieties tolerate direct sun — and some even require it. In northern climates, where sun is less intense, azaleas often prefer more sun. Choose azaleas that fit your garden's light conditions to help ensure attractive leaves and plentiful blooms.
mature size. Some azaleas, including native types, reach towering heights of 20 feet or more.2 But home gardeners have many smaller options. Dwarf azaleas grow 2 to 3 feet tall, and many garden azaleas stay 4 to 6 feet in height. Select azaleas based on mature height and width, not their size when you buy them.
- Bloom time. Azaleas are famous for springtime beauty, but they come in early, mid- or late-flowering varieties. Reblooming types flower in spring and again in fall. Extend the show for months by growing azaleas with staggered bloom times.
- Flower color and form. Azalea flowers offer something for everyone in their broad color range and flower forms from thin, spider-like petals to full, ruffled blooms. Eliminate surprises, and buy azaleas when they're blooming so you exactly how flowers will look.
- Leaf retention. Some azaleas are "evergreen" and keep their leaves year-round, but others are "deciduous," meaning they naturally drop their leaves in fall. Know what to expect from the type you choose, so you can respond appropriately if leaves drop.
Azaleas are in the same plant family as blueberries and other shrubs sometimes called "acid-loving" plants. To reach their full potential for health and beauty, azaleas and other acid-lovers need acidic soil with a pH range near 4.0 to 5.5.1 In that range, specific nutrients azaleas need stay readily available. When soil pH moves higher, some nutrients get "tied up" and azaleas suffer nutrient deficiencies that lead to yellow leaves.
Some regions of the United States have naturally acidic soil, but gardeners in areas with higher soil pH may need soil amendments, such as sulfur or ammonium sulfate, to meet azaleas' soil pH needs. A simple soil test can tell you what your soil pH is, plus recommend how to get it right for azaleas.
Azaleas also need well-aerated, well-draining soil to make sure roots get plenty of oxygen and never sit in soggy ground. Adding organic matter, such as compost, to your soil at planting helps. Always plant azaleas at or slightly higher than the level they were growing at in their nursery pot. Avoid planting azaleas too deep.
Azaleas have shallow root systems compared to other shrubs; most of their roots stay in the top 4 to 6 inches of soil.1 Because of this, they're very susceptible to water stress. Keep azalea soil evenly moist, so it never dries completely out and never stays overly wet. Sunny plantings generally need more water than shaded plantings, which don't dry out as fast. A 3-inch layer of organic mulch helps retain soil moisture and keep soil temperatures from fluctuating.
Check the soil around your azalea by hand, and water when it's dry to the touch. Water deeply and thoroughly, so each plant gets water equal to about 1 inch of rain per week in summer. Water slowly, so the water gets absorbed into the root area instead of running off. Avoid overwatering azaleas; soggy soil promotes root disease.
When possible, use drip irrigation or water the soil around the plant rather than watering its leaves. Water left on plant leaves often encourages fungal diseases. Water early in the day, so the sun can dry leaves when they do get wet.
Regular all-purpose fertilizers can fall short in providing azaleas with the special nutrients they need. A premium fertilizer designed especially for azaleas, such as Pennington UltraGreen Azalea, Camellia & Rhododendron Plant Food 10-8-6, provides your azaleas with the basic foundational nutrients they need, in the best ratio to promote healthy foliage and beautiful blooms. This special blend of nutrients includes added sulfur to help keep soil pH in the optimal zone as it feeds, plus it provides azaleas with other extras, including calcium, iron and magnesium, to help prevent nutrient deficiencies.
Pennington UltraGreen Azalea, Camellia & Rhododendron Plant Food 10-8-6 starts feeding right away, but it continues feeding azaleas for up to four months. Fertilize established azaleas in early spring and again 12 to 16 weeks later, and you'll provide the nutrients they need for the year. Broadcast the fertilizer over the area under your shrubs and out about 6 inches past the branch tips; then water the entire area well. Shallow roots are sensitive to overfertilizing, so follow label instructions, and don't overdo it.
Azaleas are prone to insects and diseases, such as mites, scale, lace bugs, and powdery mildew. Visible signs of damage can be white spots on leaves or thinning branches with white spots.
Sevin Sulfur Dust starts killing immediately upon contact and will not harm azaleas. People and pets may enter the area once dust has settled. Apply a light dusting frequently to keep your azaleas healthy and free from insect and disease damage.
Many azaleas do well with little or no pruning, but they tolerate pruning well, too.2 If you decide to prune, timing is very important. As with all flowering trees and shrubs, pruning done at the wrong time of year can inadvertently leave you bloomless the next season. Spring-blooming azaleas, for example, form their flower buds during the previous summer. You can't see them until later, but they're there. If you prune those stems in fall or winter, you'll sacrifice all your spring blooms.
To prevent lost flowers, always prune azaleas immediately after they finish blooming. This helps ensure you prune before new flower buds form. For reblooming types that flower early on old stems and bloom later on new growth, the first flush of flowers is usually the biggest. Prune these types right after their first bloom period to promote the most flowers for the next year. Prune dead and damaged wood any time. Just remember, pruned branches may mean pruned buds.
By starting with the right types of azaleas for your home and giving them the care and nutrients they need, you'll enjoy their traffic-stopping blooms and foliage for many years to come. Pennington is committed to providing you with the finest in premium lawn and garden products and the resources you need to grow the beautiful gardens you desire.
Always read the product label and follow instructions carefully.
Pennington is a registered trademark of Pennington Seed, Inc.
UltraGreen is a registered trademark of Central Garden & Pet Company.
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Sevin is a registered trademark of Tessenderlo Kerley, Inc.
1. Zins, Michael, "Azaleas and Rhododendrons for Minnesota," University of Minnesota Extension.
2. Pennisi. Bodie V., "Selecting and Growing Azaleas," University of Georgia Extension, August 2016.