Rhododendrons are one of those plants that truly shine in spring, bursting into bloom like fireworks across shady woodland gardens and partially sunlit beds. But once the show’s over, many gardeners are left wondering—what now? It’s such a letdown when the blooms fade and the plant begins to look tired or stressed as summer approaches. I’ve had years where my rhododendrons barely made it through July, let alone bounced back strong the next spring. That’s why what you do before summer really matters!
Rhododendrons (Rhododendron spp.) are native to regions ranging from the Himalayas to southeastern Asia and even parts of North America. They’re not considered invasive, but they can get temperamental if their needs aren’t met—especially heading into hot, dry months. With the right care before summer heat arrives, your rhododendrons can stay lush, green, and healthy all season long. Let’s walk through the 11 key things these beauties need to thrive!
Mulch to Retain Moisture and Regulate Temperature

Mulching is one of the most beneficial things you can do for your rhododendrons before summer sets in. A 2- to 3-inch layer of pine needles, bark, or shredded leaves helps retain soil moisture, regulates temperature, and keeps the roots cool—something rhododendrons absolutely love.
These shallow-rooted plants can dry out quickly, especially in sunny or windy spots. Mulch also suppresses weeds that would otherwise compete for water and nutrients. You’ll often find beetles, worms, and other helpful critters nesting in this mulch, improving the soil and adding biodiversity. Just keep the mulch a few inches away from the base of the trunk to prevent rot.
Water Deeply and Consistently

As spring fades into summer, consistent watering becomes critical. Rhododendrons have fine, fibrous roots that need evenly moist—but never soggy—soil. Dry spells can cause leaf curl, bud drop, and even long-term stress that carries into next year’s bloom cycle.
Give your plants a deep watering once or twice a week, depending on rainfall and your soil type. If your garden gets dry and crusty on top, a soaker hose can be your best friend. I like to water early in the morning so the leaves dry out by evening—this reduces the risk of fungal disease and gives the roots a full day to soak up what they need.
Fertilize With a Rhododendron-Friendly Blend

Rhododendrons aren’t heavy feeders, but they do need the right kind of nutrients to stay healthy. A balanced, acid-loving fertilizer formulated for azaleas and rhododendrons is best. Apply it just after they finish blooming—this supports new leaf growth and helps the plant store energy for next year’s buds.
Look for a fertilizer with low phosphorus and higher nitrogen to promote strong foliage without overwhelming the root system. I like to use granular formulas in early summer, paired with composted leaf mold in fall. Just be sure not to over-fertilize, as that can cause salt buildup and leaf burn. When in doubt, err on the lighter side!
Prune Right After Blooming

If you plan to prune your rhododendron, don’t wait too long after the flowers fade. These plants set buds for next year in summer, so late-season pruning can accidentally remove next spring’s display. Right after blooming is the perfect time to shape, thin, or rejuvenate your plant.
Pruning not only helps control size but also improves airflow and light penetration—important for preventing disease and encouraging new shoots. I like to use clean, sharp pruners and remove any dead or leggy stems. The trimmed growth often sends out fresh buds quickly, and a well-shaped shrub attracts more beneficial insects like native bees and beetles to explore its leafy interior.
Protect from Hot Afternoon Sun

While some varieties tolerate full sun, most rhododendrons prefer dappled light or morning sun with afternoon shade. As summer temperatures climb, too much direct light can cause leaf scorch and stress. If your plant’s leaves start turning yellow or brown at the edges, sun exposure might be the culprit.
Planting near tall trees or using shade cloth can help reduce stress during peak heat hours. In their native forest environments, rhododendrons often grow under the protection of larger trees—and recreating that sheltered habitat in your garden can make all the difference. Leafy canopies also attract birds, which help keep pests like caterpillars and aphids in check.
Monitor Soil Acidity

Rhododendrons love acidic soil, ideally in the 4.5 to 6.0 pH range. If your soil drifts too high on the pH scale, your plant may struggle to absorb nutrients—even if you’re feeding it. Yellowing leaves with green veins (chlorosis) are a common sign that the pH is off.
Test your soil in spring or early summer and adjust as needed. Sulfur, pine needles, and organic compost made from oak leaves can all help lower pH gently over time. Acidic soil also supports a wide range of beneficial fungi that form symbiotic relationships with your rhododendron’s roots—helping them gather water and nutrients more efficiently.
Deadhead Faded Blooms

Removing spent flowers isn’t just for looks—it helps the plant conserve energy and redirects its efforts toward leaf and root growth. Left alone, rhododendrons will try to form seed heads, which drains energy from next year’s flower production.
To deadhead, gently snap off the old bloom where it meets the first set of leaves. Avoid damaging the new buds forming underneath, which will become next spring’s flowers. This small step also helps keep the plant neat and prevents mold from forming on decaying petals—especially helpful in damp climates.
Check for Lace Bugs and Other Pests

Lace bugs can be a real nuisance for rhododendron growers. These tiny insects live on the undersides of leaves and suck out the juices, leaving behind speckled, yellowed foliage. They tend to appear in late spring and early summer, just when the plant is shifting into growth mode.
Check the undersides of leaves regularly, and spray with neem oil or insecticidal soap at the first sign of damage. Encourage beneficial predators like ladybugs and lacewings to stick around by planting nectar-rich flowers nearby. I’ve found that companion planting not only adds beauty but boosts the health of my entire shade garden.
Avoid Disturbing the Roots

Because rhododendrons have shallow, fibrous roots, it’s important not to dig or plant too aggressively around them—especially in late spring or early summer. Disrupting the root zone can cause stress and affect bloom performance for the following year.
If you want to add companion plants around your rhododendron, opt for shallow-rooted, shade-tolerant varieties like ferns, hostas, or woodland phlox. These create a beautiful understory without competing for root space. A calm, undisturbed root zone helps keep the plant stable, hydrated, and productive all summer long.
Thin Inner Growth for Airflow

Dense, tangled growth can trap moisture and limit airflow, especially in humid climates. This creates ideal conditions for fungal diseases like leaf spot or powdery mildew. Thinning out some of the inner branches allows light and air to circulate through the center of the plant.
I usually do this kind of thinning during my post-bloom pruning session. I remove crossing branches, twiggy growth, and any interior stems that look weak or spindly. The resulting open structure not only helps the plant breathe better—it creates little hiding spots for birds, toads, and beneficial insects to rest in the heat of summer.
Keep a Steady Moisture Routine

One of the biggest stresses rhododendrons face before summer is erratic watering. Going from dry to drenched and back again causes root stress, leaf curl, and bud drop. Establishing a consistent moisture routine ensures your plant heads into summer strong and hydrated.
Aim to keep the soil evenly moist—not wet. Check the top inch of soil with your finger and water when it feels dry. I’ve had great results with a layer of mulch and a drip hose on a timer, which takes the guesswork out of watering. A hydrated rhododendron is a happy rhododendron—and one that’s ready to face summer without faltering.