14 Tips For Beautiful Blooming Rhododendrons This Season

Springtime means rhododendron time. These giant flowering shrubs are a spring favorite of gardeners everywhere. Their flowers are trumpet-shaped and come in a variety of pastel colors. Unfortunately, their bloom time can be cut short due to rainfall, or rising temperatures. I suppose that’s part of what makes them so magical though.

Rhododendrons are very low-maintenance plants. Following a few easy plant care recommendations is the best way to get the most out of these flowering shrubs. But there are also a few tips and tricks you can utilize outside of basic maintenance.

Let’s take a look at 13 things you can do to extend the flowering season of your rhododendrons as long as possible, while also keeping your shrubs healthy all year long!

Plant Several Varieties

The best way to fill your garden with rhododendrons all season long is to add rhododendrons that bloom at various times. There are rhododendron varieties that can bloom from January through August, even though peak blooms usually happen from March through May.

 Here are a few ideas for staggering your rhododendron blooms. Please keep in mind that the mentioned bloom time may vary depending on where you live.

Choose The Right Location

When you are planting your rhododendron, you will want to choose a spot in your garden that doesn’t change too drastically from season to season. Dappled sunlight, and protection from the wind is important all year long.

If your rhododendrons are planted under deciduous trees, they will begin to receive a lot more sunlight in the winter once those leaves have dropped. Providing a proper location is critical to make sure your rhodies stay perennial and that you aren’t replacing them each seaason.

Mulch For Moisture

Adding mulch around the base of your plant will help to retain moisture in and around your rhododendron. The right type of mulch will also keep weeds at bay.

Weeds can suck up a surprising amount of water from nearby plants. This can affect rhododendrons especially because of their shallow and fibrous roots.

Maintain a Regular Watering Schedule

Rhododendrons are shallow rooted plants, meaning that having moist soil around is extra important! It is easy to forget about your rhododendrons after the blooming period has passed, but the summer months are the most important times to keep your rhododendrons watered.

Rhododendrons need about one inch of water per week. Depending on your weather, and climate you may need to water supplementally. If you are unsure how much water your rhododendron has received, you can use a rain gauge or you can stick your finger in the dirt and see if it is moist or dry about one inch down.

Provide Just Enough Sunlight

While most rhododendrons are happy to spend their time in the shade, it is important that they receive some sunlight in order to produce flower buds.

If they don’t receive adequate sunlight, don’t expect them to produce beautiful blooms on a regular basis. At the same time, they can’t be planted in a place that gets too much sun, or they will end up crispy and won’t flourish.

Fertilize Carefully

Rhododendrons can benefit from an application of fertilizer. You do need to be careful while applying though. The roots of rhododendrons are fibrous and shallow, making it more likely for them to fall victim to fertilizer burn.

If you do opt to fertilize your rhododendrons it is best to do so in the spring or fall with an application of a fertilizer for acid loving plants, such as holly tone.

Add Compost When Needed

Adding compost to your gardens is a no-brainer in my book. Compost adds organic matter which improves the structure of your soil, while also giving your plants much-needed nutrients.

Rhododendrons prefer moist but not wet soil. Adding compost will help the soil around your rhododendrons to retain moisture without water logging the roots.

Deadhead Spent Blooms

Deadheading your rhododendrons will not cause them to rebloom in one season, as is true with many perennials. But, removing the spent blooms will help the rhododendron to focus its energy elsewhere, including the formation of buds for the next year.

Deadheading rhododendrons is a simple task. You can use your fingers, or garden snips to cut just below the blossom. This can get sticky, so wear some garden gloves or be prepared to wash up after!

Only Prune as Needed

Pruning your rhododendrons if you would like to control the size or even the shape of your plant. Removing any branches; this includes dead branches or branches that may have been damaged over the winter is best done in Early Spring.

When it comes to flowering, pruning will help the plant focus its energy on creating the buds and not on trying to revive some of those unhealthy branches.

Regularly Monitor Your Soil

Rhododendrons love acidic soil. They also love well draining soil that has lots of organic matter. These are the conditions that rhododendrons live in when they are in their native habitats which are full of leaf litter and pine needles.

You can use a soil pH monitor to see where your soil falls.If your soil is a bit too alkaline you can amend the soil with wettable sulfur. Steer clear of  aluminum sulfate because it is toxic to Rhododendrons.

Monitor Daily For Insects

There are many common insects rhododendrons will encounter during their growth season, including black vine weevils, lace bugs and spider mites. Let’s take a look at each pest you’ll want to keep an eye out for.

Black Vine Weevil

A common garden pest, black vine weevils love rhododendrons. They will spend their entire life feeding on varying parts of rhododendrons, from roots to leaves and everything in between. Signs of black vine weevil may be small holes with no insect in sight. This would be because they are night time feeders.

Treatment of black vine weevil could include beneficial nematodes, as well as keeping your garden clear of hiding spaces for the grubs such as old mulch or leaf litter.

Lace Bugs

Rhododendrons can be attacked by lace bugs, which are flying insects with lace like wings. These flying insects love to feast on heat stressed plants and are most active in July and August. You may have a lace bug infestation if you see small yellow spots on your leaves, and eggs on the underside. You will also notice the actual insect flying about your rhododendrons.

Treating lace bugs starts with using a broad spectrum pesticide, although you will need to reapply this pesticide frequently and according to the labeled instructions.

Spider Mites

Spider mites are very small insects that can be distinguished by two small black dots on their back. The most noticeable symptom of spider mites is not the insect, but their webbing that they use to protect themselves and their eggs. The leaves of your rhododendron will take on a speckled appearance.

Treatment of spider mites is easy. You can spray your infected plant down with your garden hose which will knock the mites right off. Keeping your rhododendrons well watered will keep the mites away as well. Mites prefer drought stressed plants, the healthier the plant the less mites you will have!

Monitor Weekly For Diseases

The most common rhododendron diseases you’ll see are chlorosis, fungal die back, leaf gall, and petal blight. Winter burn can also cause problems even though it’s not a “true” disease. Let’s take a look at the most common diseases to monitor for.

Chlorosis

Chlorosis is common on rhododendrons. If you have ever had yellow leaves on your rhododendrons but the veins stay green, you have had chlorosis. This  usually happens because your soil is lacking iron.

Don’t get this confused with the typical dropping of older leaves, those leaves will be closer to the center of the plant and will be totally yellow.

As with any soil amending, it’s best to run a soil test before adding anything. If your soil does come back with lor iron, you can use wettable sulfur to lower the pH of the soil. If this isn’t a great option for you, moving the rhododendron to a better spot is also doable.

Fungal Dieback

As the name will lead you to believe, this is a potentially devastating fungal disease for your rhododendrons. If you notice an entire branch or two that are completely dead on a rhododendron in your garden that you would assume is healthy you may have fungal dieback.

You can diagnose this disease right at home by scratching the bark of an affected branch. If you see green underneath your plant is healthy, but if it is red you have fungal dieback.

Pruning the infected branches out is the best way to try to cure this disease. Applying copper fungicide would come next.

Leaf Gall

Leaf gall is a fungal disease that affects your rhododendron leaves. You may notice leaf gall by distorted leaves that will become thicker and curl. The leaves will then turn white and harden.

You can remove the infected leaves by hand.

Petal Blight

This fungus attacks the flower petals on your rhododendrons. It will start as small brown spots on your petals that will rapidly spread. You will likely lose your flowers for the year. The petals will drop, and continue to spread the fungus.

The best thing you can do to prevent this fungus is to keep your garden free from debris. Raking any fallen, infected petals and taking them far away from your plants will go a long way.

Winter Burn

While common, winter burn isn’t an actual disease. It is however a common issue that many rhododendron growers experience. The main reason this occurs is because of a lack of water over the winter. Symptoms of winter burn that you may notice are large brown splotches on the leaves.

Keeping your rhododendron watered will be important.  WInter burn commonly occurs on rhododendrons that are receiving too much sunlight in the winter, or are getting hit with too much wind.

Make sure the place you have your plant growing in doesn’t change too much from season to season. Anti-desiccants can be applied to help prevent water loss through the plant’s leaves.

Protect Them in Winter

These beautiful shrubs will be covered in flower buds come early spring. While they are very cold tolerant, a sudden late frost can zap those buds.

Rhododendrons do not need to be covered all winter long, in fact they need the cold to perform at their best. However, when a later spring frost is in the forecast it’s not a bad idea to keep some burlap or other plant fabric nearby to cover the buds and protect them. This will ensure that they will not be damaged and will bloom at their best!

Be Patient With Them

If you are dealing with a rhododendron that skipped a blooming season, do not worry. Consider the age and type of rhododendron you have. Young rhododendrons may need a season or two to get comfortable in their new home before they start producing those prolific blooms you are expecting.

On the other hand, there are species of rhododendrons that do not bloom every year. Take a peek at your plant tag and do a little homework to see if you should be expecting flowers every spring or every other.