While this article applies to Rhododendrons , 99 % of it also applies to planting and care for Azaleas , as they are in the same genus , Rhododendron . While all azaleas are rhododendron , not all rhododendron are azaleas . Leaves and bloom characteristics differ , but website demand , soil , and care are for the most part very . course , as with anything in horticulture , there are exceptions and alwaysread the plant tagof the cultivar you ’re purchasing to understand its requirements .
There ’s good reason that Rhododendrons are one of the most popular landscaping plant life in the earth . Their long life , beautiful flowers , unique , mostly evergreen leaf , beautiful shape , and relief of care make them a dependable standout in anyperennial garden . If you take care to plant a rhododendron properly and accompany some basic rules of fear , it can conceivably live in your garden for as long as you do . No matter where you live in North America , there is a variety show of Rhododendron for your climate and grease .
For those who are fresh to rhododendron , you might believe that most search the same because you ’ve only view rhodies at your local big box store plant nursery . Nothing could be further from the trueness . This long - lasting shrub appear in an enormous number of shapes , size , and flower type , from very little shrublets to imperial Tree . Some have scented efflorescence , some have little prime , and some have efflorescence clusters larger than a playground ball . One matter rhodies have in vulgar is that their flowers bloom for 2 - 3 week of the year , which makes the foliation an authoritative focal detail for the 95 % of the year it ’s not bloom . luckily , most Rhododendrons ( but not azaleas ) are evergreen and have beautiful deep green leaves .
Not every Rhododendron has the same necessity , so it ’s wise to know what your plant life require before planting . Do some inquiry online or if you ’re previous school , with a book . At the very least , translate the flora tag tied to the stem ( so many people fail to do this one simple thing that I ’m stunned).Knowing your rhododendron ’s sun / shade requirementsand its mature height are vital to find the expert spot in your garden where it will fly high . bankruptcy to recognize the mature meridian wo n’t cause problems this time of year or even the next , but in 5 - 10 years , you ’ll be faced with a works that obscures your picture windowpane or trying to transplant and then rehab a mature Rhododendron , which does not always go well .
Where to plant your Rhododendron
Dappled shade is optimal
It ’s a common misconception that rhododendron only like deep shade . While this is true of some varieties , it ’s not on-key for all . In fact , if you impoverish certain varieties of sun , they ’ll only produce a few peak each year . In the wild , Rhododendrons are constitute at the edge of woodlands , where they thrive in dappled shade . Find a like setting in your home garden – good afternoon or mottled ghost , dirt that drain well , and shelter from cold , dry out wind .
Rhododendrons love early morning sun
The flower buds on spring - blooming rhodies require brightness level in late summer and fall to stimulate flower bud development . If visible light is too low , the heyday show will be minimal . ensure the industrial plant receive enough direct light but not so much that the leaves burn . A good rule of thumb is to locate it where it will receive verbatim sun until midday and then good afternoon shade .
Give it a little shelter from wind
Persistent breaking wind , especially in wintertime , can damage or dehydrate the foliage . If you must constitute it in a peculiarly impractical position , consider build a shelterbelt around the plant for the coldest months – wrap burlap around it , but do not let the burlap connect with the plant .
Avoid sidewalks and foundations
Do not plant a rhododendron next to a sidewalk or other cement structure , as the lime that leaches from the concrete creates an alkaline soil . Rhododendrons need just the paired – anacidic or at least slightly acidic soil . If you must found near a concrete structure , monitor the soil ’s pH scale per year and add appropriate amendments to lower the pH.
“ Rhododendrons and azaleas are healthiest in sluttish shadowiness , specially under oaks and pine with the lower branch trimmed . Do not choose a localisation near maples , elms , ashes , or other Tree with shallow competitive root systems . Some varieties of azaleas and rhododendron may survive in full Dominicus , but avoid implant them in a south , southwest , or west exposure , especially if heat and light are reflected on the industrial plant from a nearby construction . In impenetrable shade , the plants run to grow spindly and do not blossom profusely . aegis from wintertime ’s cold drying winds is also suitable . Avoid area with onetime constructor ’s rubble , peculiarly mortar which can arouse the soil pH above the desirable range … Do not plant rhododendrons under downspouts or at the sharpness of sidewalks and driveways . Do not plant in space where other rhododendrons have wilt and died , because the site may still be contaminated with disease organism . ”
Choosing a Rhododendron
Likeroses , rhododendron varieties are vast and vary in flower color , form , and ripe size . It ’s worth it to expend some meter and look theAmerican Rhododendron Society resource on rhododendronsbefore you make a determination . Your local conditions conditions are also crucial , as are the amount of sun the plant life will receive , flatus at the plant land site , soil case , and dirt drainage .
Consider the foliage, not just the flower
The foliage of Rhododendrons alter greatly . Some have large ovate leaves , blue leaves , large leaves , small finger - similar leaves , and most variety are evergreen . Some salmagundi are cover withindumentum – a hairy covering of brown , tan , or silver on the underside of the leaves . This is strikingly beautiful as the leave move in a breeze . On some variety show , new leaf is a unlike color than sure-enough foliage , which make for an interesting display .
Optimizing garden soil for Rhododendrons
Soil pH is critical
Your garden stain ’s drainage andpH ( acidity level)are very significant for the health of your Rhododendron . Alkalinity is a rhododendron ’s worst enemy , turning the leaves chickenhearted between green vein and generate it an overall insalubrious show . A rhodie prefers a pH between 4.5 and 6.0 ( alkaline dirt is in the 7.0 + range ) . A dirt psychometric test should be your guide to determine your pH grade . If you need to take down the pH , use wettable sulfur or ferric sulfate . NEVER utilise ammonium sulfate ( a common treatment for hydrangeas ) , as this chemical substance is toxic to the okay surface roots of rhododendron . Also , do n’t essay to lower the pH speedily or you may traumatise the plant – it should be lowered by .5 each season until the target pH is achieve . You should see the bush improve significantly for every .5 the soil pH is lowered .
Soil needs to drain quickly
A Rhododendron ask sufficient soil aeration – the soil want to drain apace , as their roots are very fine and will “ drown ” in muddy soil . At planting time , make certain that roughly one-half of the surround soil contain fresh constitutional matter and stratum compost over the theme zone every year . The ARS recommendssphagnum peat moss , pine or true fir barque mulct , compost , and aged , chopped leave should be worked into the soil to a depth of about 12“(with the elision of leaves from Walnut Sir Herbert Beerbohm Tree , which are toxic to rhododendron and azaleas ) . The compost will notice its way into the soil over the growing season , assure a constant addition of organic material to the soil around the plant . If your landscape grease is heavy clay or if you ’re planting in a low - lying area prone to waterlogging , weigh set your Rhodie in a nurture bed so you could easy supervise the dirt .
“ enkindle beds should be built up with 12 to 18 in of organic textile such as oakleaf mold , other shredded acid type compost , pine bark , coarse peat moss , or rot pine needles . In heavy clay soil [ rhododendron ] should at least be place on top of the ground and the root ball covered with some of the above constituent materials . If the garden surface soil is not heavy clay but is a loose loam or sandy loam containing much humus , the plant can be prepare in a 20 - inch cryptical hole with at least the top inch or two of root ballabovethe soil surface . The bottom of the hole and area around the root orb should be satisfy with a smorgasbord of adequate parts loam and some of the above - mentioned organic cloth . “
How much water does a rhododendron need?
Although too much water supply in the soil is harmful to Rhododendrons , not enough water and drought are harmful as well . But if you prefer a right site and works correctly , you should have few or no problems after your plant is establish .
Shallow root systems make Rhododendrons sensitive to heat and drought
Rhododendron root are very shallow and originate like a spider vane close to the soil surface . They have no taproot and , as a result , are very prone to drought . verify your Rhodie receives consistent wet , specially the first year after planting when the tooth root system is developing . The rule of pollex is to keep the soil damp but never soggy and make indisputable it receives 1″ of water each week in the absence of rain . Add a 2 - 3″ layer of constitutional mulch around the ancestor zone to retain wet , control sens , and isolate the solution from heat extremes . If temporary go above 95 , Rhododendron leaves appreciate a misting of water to prevent desiccation .
Planting Rhododendrons
rhododendron can be planted almost any time of year except wintertime . The best time to plant is early spring , with late fall being a cheeseparing 2d alternative . come down plantingis the favorite time if you live in a hot surface area because the warm soil permit the stem to institute before wintertime set in .
Never plant the rootball below the level of the surrounding soil – it should be planted several inches above to earmark for adequate drainage around the beginning . Planting a Rhododendron too late can eventually kill the plant .
Loosen and expose the roots
After removing your new Rhododendron from its container , judder loose the pot medium and expose as much of the root organisation as potential , being careful not to damage the roots . With your fingers , gently untie the root and untangle any you see . If the works is rootbound ( roots wrapping around in the pot ) , thoroughly loosen them with your fingers and prune some of the outer , entangled beginning . This will excite new origin growth after constitute and allow water and food to penetrate the root mickle . If the plant life has been field grown and is delivered wrapped in burlap , completely remove the burlap before planting , and put it aside – do not plant the Rhodie with the gunny wrap in the cakehole and particularly not still surrounding the rootball . Even though the burlap may slowly deteriorate – it is biodegradable – it can trammel root increment into the palisade soil and take age to degrade .
Fertilizing a Rhododendron
Rhododendrons rarely suffer from fertilization problems, so check the pH first
Rhododendrons need niggling to no fertilisation in well - maintained soils after they ’re established . But if your Rhodie is exhibiting symptom that go you to believe it may want to be fertilized , chances are it ’s a pH problem , so checker that first ( Rhododendrons opt a pH of 4.5 - 6.0 ) . Run a pH trial of your soil and adjust it lower , if necessary , with ferrous sulphate or wettable sulfur .
Too much water may damage the roots
Rhodies may also scramble if their root are perpetually wet . To help the land drain easily , add 2 - 3″ of compost around the root zona each saltation and fall . A layer of wood microchip mulch is also helpful to isolate the roots .
Only use these fertilizers if necessary
If you ’ve followed the above testimonial and your works is show unaccented signs of emergence , an constitutive atomic number 7 fertilizer may be utilitarian for a slow provender . Use cottonseed meal , canola meal , fish meal , or blood meal . Pelletized high - nitrogen fertilizers are not recommended as they may “ sting ” the fine stem .
Rhododendrons disease and insect problems
One of the most alarming signs to a new Rhododendron owner is a sudden leaf drop-off when the plant look to throw away many of its leave . The good news is the cause of folio driblet is commonly condition and not disease . According to theRoyal Horticultural Society , “ foliage fall can come about following a flow of drought and is usually preceded by drooping and rolling of the leaves . The oldest leafage are the first to drop , and high leaves may show brown at the leaf hint or boundary . folio drop can also come about watch extended periods of waterlogging . As with all evergreen shrub , each year a symmetry of the foliage ( principally old parting ) are cast off in natural spring and summer . This is normal and not a cause for headache . ”
rhododendron are trouble by few insect , but are susceptible to fungous diseases , especially in poorly draining soils . For information on Rhododendron diseases see thediseases foliate from the American Rhododendron Society .
