Rhododendrons and Azaleas www.floweringshrubfarm.com/rhododen.htm
I am a grower of Native species Rhododendrons and Azaleas including; Rhododendron maximum (Rosebay Rhododendron), Rhododendron nudiflorum or Rhododendron periclymenoides (Pinxterbloom Azalea), Rhododendron calendulaceum (Flame Azalea). Sometimes people want to get rid of their large old Rhododendrons and so I may have some of those I have saved as well. Watch for pictures of each current crop below added from my picture-newsletter. Link to Rhododendron catalog at bottom. I'm starting a new crop of Pinxterbloom azalea in spring of 2010.
Flame Azalea in center, R.corolineanum slightly below it, R. maximum on right (00525rhododendrons052506). Click for a larger version.
1. Rhododendron Site Selection:
A careful site analysis to determine pH, drainage, presence of salt & nematodes is best done before planting. A northern exposure allows less direct light so growth slows early in fall and prevents early spring warming, plants growing in the shade of trees will enter dormancy earlier and respond to warming later, If a Rhododendron is in an unsheltered eastern or southern exposure there is more bud damage caused by early morning sun touching frozen leaves or flowers (a condition similar to sunscald), avoid planting at the bottom of a hill where frost can damage plants and in windy areas provide a wind break.
2. Soil and Water
When amending soil you can add clay to sand but never add sand to clay. Some have put a layer of 4 inches of sand on top of the clay in a mound but this often accentuates wind problems causing dessication. Provide a drip irrigation water line.
Rhododendrons survive with difficulty without a constant supply of moisture. They must never sit in stagnant water as stagnant water will kill roots. Grow in a course acid medium, a slow to decompose material that provides air spaces in the soil, a moisture retentive material that doesn't decompose rapidly. Sometimes Rhododendrons grow great for 3 or 4 years and then start to decline. Its often caused by decomposition in the soil and a reduction of particle size and airspace between particles. It might be time to transplant into a better soil medium (in spring).
PH is fine between 4.5 and 6.5, practice careful neglect as most problems are man made, the addition of dolomite or gypsum to plantings seems to darken foliage color and increase buds but agricultural limes are extremely poisonous to them.
Some people scallop the ground in heavy soils and provide a land drain leading to a soakage.
Then they fill the scallop with gravelor sand. Rhododendrons and azaleas are planted in close proximity so they merge as they grow.
I like to mulch the surface with pine neadles, pine bark and ground oak leaves to a depth of six inches then I plant in volcanos. Soaker hoses are buried in the mulch and I water a couple times a week even when it rains.
My Rhododendrons are all in pots which allows me a level of flexibility when designing a garden that most people dont have.
Rhododendrons roll their leaves as a defence against wind or cold (01219rhododendroncarolineanum121909.jpg). Click on the picture. Crop 321
Ericaceous plants (like rhododendrons) have low nutrient requirements.
10-6-4 is being advised by the American Rhododendron Society.
At Azalea House we have a three pronged approach.
First fertilization through decomposition. We mulch with Oak leaves, evergreen needles, alfalfa and washed seaweed (Use whats available, hang the rest). Cottonseed meal or fish meal can be sprinkled between the layers. If calcium is needed sprinkle on dolomite (agricultural limes can kill them).
I add a couple handfulls of Espoma Hollytone each year in spring.
Sometimes I apply triple phosphate in winter.
Third, remember most problems will be caused by you. Practice careful neglect.
Make sure the potted or root balled plant is soaked in a water bucket several hours, before you plant so that water penetrates deep within the roots. Cutting back root tips makes for easier transplanting, if plant is badly root bound make 4 vertical quadrant cuts to interrupt root circling. Root laceration allows the plant to regenerate new roots.
Plant shallowly in a high humus, porous soil. Test soil pH. Lay down edges of burlap (without disturbing roots) so it does not interfere with root growth, remove nylon cords as they wont break down. Remove name tag. Newly transplanted plants cannot be allowed to wilt for any period of time.
After planting, water the area thoroughly so the surrounding soil is moist to start. Transplants require special watering until fully established. Poor watering causes root ball to become impervious to outside moisture.
Rolling of leaves when its warmer may indicate the soil is to dry, the existence of root rots or some other root related problem but in winter its just the rhododendrons way of reducing its use of water (01219rhododendronmaximumleaf121909.jpg). Click on the picture. Crop 321
All Rhododendrons that are going to be pruned should be pruned immedialy after the plant ceases to flower. They develop flowering buds for the following year during summer as day length gradually shortens (these are internal and can't be seen til the following spring).
Pruning Azaleas and Small leaved (lepidote) Rhododendrons:
Azaleas and small leaved Rhododendrons may be pruned back to anywhere along the stem due to the presence of dormant growth buds all along the stems. I prune with a hedge pruner pruning to a shape slightly larger at the bottom than the top. P.J.M. is a lepidote rhododendron.
Pruning Large leaved (elepidote) Rhododendrons:
Large leaved Rhododendrons have a point each year from which growth begins. All flower buds congregate at this point. Its called a growth joint and pruning should be back to just above it. If you prune too high you will get dead stubs, too low and you may not have flowers. 'Roseum Elegans', 'America' and many others are elepidote Rhododendrons.
Cutting Back a Mature Specimen:
Revitalization of an older or badly damaged plant must use new wood as old vascular bundles no longer produce bud wood correctly. The method I use is to cut the plant back to a four inch stub and fertilize generously early in the spring before, and up to just after (within a couple days of) flowering time. Given no root damage, even the largest rhododendrons can be cut back in this fashion, to then recover and flower again in three or four years. They'll usually leaf out as late as June or even July so dont give up and throw it in the dump until fall.
For those who want a natural shape.
Do you mean the shape plants attain in the wild by being denuded of large parts by grazing animals or after a tree falls on them. Plants in the wild are being pruned regularly. They respond to this natural pruning by producing more buds and growth (or in some cases not). Everyone knows the Rhododendrons in North and South Carolina bloom prolificly in the forest. Its not because there are no deer. If you want Rhododendrons in your garden its a good idea to graze on them a bit for their own good. Some years I only remove a couple flower buds.
Oh, while I'm on that subject, plant masses of rhododendrons and azaleas. Only one plant in an area deer might graze in probably means all the buds will be eaten. Closer to the house or in masses and chances are you will still have enough flowers.
In the first winter after planting rose cones with the tops removed have been used for protection. If using burlap leave the top open so that snow can fall on the plant and there is good air circulation. The point is to protect the plant from early morning sunlight that might cause sunscald and wind that could dessicate. If you have provided an optimal location protection should be unnecessary after the first year. Don't make saucers around plants as ice will form, split the bark and kill the plant.
Rhododendron catalog Native Pinxterbloom Azalea (R. nudiflorum), Swamp Azalea (R. viscosum) and Rosebay Rhododendron (R. maximum) in a 3 gallon pot for $30.
"Henning's rhododendron and azalea pages feature descriptions, cultural, and trouble shooting pages as well as companion plants." The link is: http://home.earthlink.net/~rhodyman/rhody.html
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