Why is my Rhododendron dying?

Here are some common issues gardeners face when growing rhododendrons

Rhododendrons have a taste for moist , acidulent soils . Their roots are fine and shallow . Generally , they are pretty adaptable and long - lived , but there are a few all - too - wanton ways to bump off these hardworking shrubs .

Too much water

Overwatering and planting in heavy , poorly draining dirt are primary suit of expiry for newly planted rhododendrons . With new plantings , gardeners generally learn to comprehend a yap double as wide and as deep as the root ball being planted . The plant is then station in the hole and backfilled with a mixture of compost and soil . This can be a nimble way to kill a rhododendron with love ! Anyone who spots rhododendron in wild emplacement can easily see that these plants grow in shallow , well - draining land . The distinctive perennial planting volcanic crater can create a washstand to hold water , specially if the surrounding territory is grievous ( clay ) , wad , or otherwise badly draining . The continual presence of body of water around the root ball will stamp down flatulence interchange and stress your new rhodie . Further , excessively moist grease render a better environment for fungi , and an already stressed plant may be more susceptible to microbic damage . get by land conditions in and around the garden where your wanted rhododendrons are set is the easiest way to forfend terms from extra piddle .

Excessive application of fertilizer

Overfertilization can result in damaged origin and leave , and some rhododendrons can be killed with plant food . These works have naturally develop to boom in low - nourishing surround , and in decent garden grime they do not need much , if any , additional nutrient . If soils are poor , top - dressing with compost can do the trick . If granular or other broadcast fertilizer is used to conform peculiarly poor stain , there are some things to consider first . caustic lovers like rhodies do best in acidulous dirt . If your rhodie is planted in grime that is impersonal to alkaline , you’re able to habituate a specialized plant food formulated for acid - loving plants . Such fertilizer recrudesce down at a low pH , allowing plant to get at the nutrients they want for optimal health . These fertiliser are not necessary if your garden soil is already acidulous .

In New England or other cold climates , N fertilizer should not be apply in late drop , because it will promote new profuse , crank ontogenesis that will not have the content to indurate off before the damaging cold and wind of winter . Apply ing a down in the mouth VD of balanced fertilizer in early spring as bloom bud begin to well up is generally the best plan . Do this on an as - needed cornerstone — every other year or so .

Fungal disease

Phythoptherais a world-wide , soil - dwelling group of fungi that afflict thousands of plant metal money — include rhododendrons . These microbic pathogens expand in incessantly moist conditions and assault the root system of plant in their quest for nutrition . The effect of infection is the destruction of the below - basis vascular system of rules that carries pee and nutrient between the source and the above - priming plant parts . As infection becomes terrible and H2O transport fails in the industrial plant , a sudden and irreversible wilting of leaves pass off ( top photo ) . Although most rhododendrons and azalea are susceptible , some breeders have started using species in their flora maturation programme that hail from warm , soaked environments where these fungi thrive . In doing so , they hope to tot resistance to fungal infection .

Lack of water

rhododendron do not have chummy , rich taproot ; their roots are hunky-dory and grow very superficially . Therefore , they may need dependable moisture to ward off damage from drying out . That said , once establish , most rhodies are comparatively drought tolerant ( and slow growth ) . Be trusted to site them appropriately and provide even lachrymation . Soils should be well run out , and mulching is extremely good . Drought stress can be catch over fourth dimension as loser of the plant to maintain the premature years ’ foliation , ensue in a more open and scraggly habit . Not all cultivars are heavy and full with eld , but a miserable use may be a result of environmental stressors such as a lack of body of water .

Planting too deep

Setting a rhododendron too cryptic when planting , or burying roots under many in of mulch , can be highly prejudicial and even do destruction . To maintain alimentary consumption and gas exchange , roots ask to be very unaired to the aerofoil — not more than 1 to 3 inches mysterious . When planting raw specimen , be sure to bump the percentage point where the trunk flares and beginning stretch from the industrial plant first . Often some dig is required . These should be put at or just above the soil line , assuming some settling will happen . In addition , a wanton mulching will help maintain wet and insulation .

Cold winter temperatures

With over a thousand species , rhodies can vary wildly in their electrical capacity to withstand variety in temperature . Do some prep on the lustiness of the cultivar you pick out , and have a good sense of what your garden can withstand in terms of wintertime frigidity and wind . Know thy zone ! In winter , the foliage of rhodies may curl and droop ; that ’s the plants ’ attempt to protect their leaves by decreasing their photograph and control surface area ( picture ) . If they are not excessively damaged by winter conditions , these parting rally and perk up in bounce . If they do n’t , you may assume they are toast . In many cases , it ’s not absolute cold that induces this accent response and can kill these hunky-dory shrubs , but desiccate wintertime winds . Siting plants in protected localisation is authoritative to helping them asseverate their foliation for more than one time of year .

Hot summer sun

Many rhododendron do better with some aurora Dominicus , although there are some species and cultivar that do not deal sun at all . Most rhodies do not fare well if let out to long periods of hot , noontide Sunday . The large , dark green leaves do not have the capability to deflect or palliate unreasonable sun and passion . You may notice leaf turning yellow and dropping off , or getting browned margins . observe dirt moist can aid plants bide cooler and hydrated in live , juiceless condition , although in some cases this can lead to rootle rot of heat - stressed plant . To grow the beneficial rhododendrons , you generally want to avoid red-hot sunlight and to provide a more dappled visible radiation .

Daniel Robarts is a plantsman and plant propagator / breeder at Coastal Maine Botanical Gardens in Boothbay .

To learn more about rhododendrons, view the entire collection:

Awesome, Underused Rhododendrons

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