If this occurs, a soil test is suggested for exact recommendations on adding a soil amendment to the soil in order to adjust the pH. Materials commonly used to lower soil pH are wettable sulfur or ferrous sulfate.
Do not use aluminum sulfate to acidify the soil; it is toxic to rhododendron and azalea roots. Avoid planting azaleas near concrete sidewalks, driveways or foundations that may leach out lime which raises the pH. In rare cases, the pH may be too low. This is equally serious and must be rectified.
The recommendation is usually to use dolomitic limestone. Soil Mix: About half of the planting medium should be organic material. Combinations of sphagnum peat moss, pine or fir bark fines, compost, and aged, chopped leaves should be worked into the soil to a depth of about 12". Oak leaves are excellent. Make sure there are no walnut tree roots or leaves in the soil. All parts of walnut trees are toxic to rhododendrons and azaleas. Pine bark is particularly good because substances in the pine bark are thought to inhibit fungi that cause root rot.
Adding a large amount of organic matter will raise the bed, which will improve the drainage and aeration of the soil. Inorganic materials that may also be added to soil include perlite, vermiculite or small diameter lava rock. Keep Moist: Rhododendrons and azaleas will not survive in wet, poorly-drained soil. Who is right? I read somewhere these plants need 6 hours of sun.
Thank you for your help. I forgot to ask in my previous comment, what time zone do I live in? I always planted my annuals after Mother's day because I was not sure of my time zone. Please see the Planting section of this page above for advice on where to plant rhododendrons and what kind of lighting they prefer.
You are likely in Zone 7a, which gives you a lot of options when it comes to gardening! Skip to main content. You are here Gardening » Growing Guides. By Catherine Boeckmann. Buying Plants When shopping for rhododendron or azaleas, pay attention to when they flower. Early varieties can blossom in March, late ones into July or even the fall. Buy plants that are a deep green not yellowed , not wilted, and well watered. Check the soil in the container with your finger and avoid plants that are bone dry.
Their thin petals shatter in the heat. In hot climates, buy plants in 3-gallon pots rather than 1-gallon pots. Small plants, with their fewer roots, struggle in the hot late spring and summer. Choosing and Preparing a Planting Site Most large-leafed varieties require dappled shade; avoid deep shade or full sun. A sunny spot that receives a few hours of shade is perfect.
See regional guidelines below. Soil should be well-drained, humus-rich, moist, and acidic pH 4. Amend planting areas with compost, peat moss, or a substitute, only if your soil is poor. Learn more about soil amendments and preparing soil for planting. Azaleas and rhododendrons have shallow root systems and need moist soil and mulch to keep them from drying out. Planting in Cold or Temperate Regions Zones 3 to 6 Plant in full sun to increase flowers and avoid mildew problems. Shrubs need a minimum of 6 hours of full sun daily.
Plant on the sheltered side of a windbreak. If subjected to cold, dry winds, their leaves and buds dry out and die. Planting in Warm or Hot Regions Zones 7 to 11 Plant in a site that receives afternoon shade, especially in hot areas. In tropical zones, azaleas will bloom in full shade. Space plants 2 to 6 feet apart, depending on their estimated mature size.
Dig a hole as deep as the root ball and 2 times as wide. Set new plants so that their top roots are at soil level or slightly below. If you plant them any deeper, the roots may rot. Fill the hole half full with soil, then water it well to settle the soil before filling with remainder of soil. A lack of water reduces flower-bud formation.
In fact, this can keep the trunk too wet and encourage rot. Always leave a few inches around the trunk free of mulch. Fertilize azaleas and rhododendrons sparingly and only when flower buds swell in the early spring, even if they are fall bloomers. Heavy applications of fertilizer will burn the plants. Water plants during the summer if rainfall is less than 1 inch per week.
After flowering, deadhead where practical, to promote vegetative growth rather than seed production. In regions with severe winters, wrap evergreen rhododendrons with burlap in the fall and apply extra mulch around the base of the shrub.
Azaleas and rhododendrons may be transplanted at any time during the growing season, but they transplant most successfully during fall or early spring, when they are dormant and temperatures are cool. If you need to reduce height, prune after flowering in the spring. Otherwise, just remove dead, damaged, or diseased branches at any time of year.
On young and old plants, simply snap off spent flower stalks by bending them over until they break away from their stems. Be careful not to damage growth buds at the base of each flower stalk. It blooms mid-season with violet-blue flowers. Zones 7 to 9.
Zones 5 to 8. Pale pink flowers bloom in mid-season. It grows to 4 feet and bears deep purple-pink flowers. Zones 3 to 8. It bears small, light purple flowers.
Excellent in the front of a border or in a rock garden. Vegetable Gardener's Handbook. What do you want to read next? Growing Hellebores: The Christmas Planting Fall Bulbs for Spring The Best Fall Flowers for Your We live in Maryland, and are fortunate to have a woodland border lot. When we moved to our house 20 years ago, there were a number of rhododendrons as well as many azaleas and mountain laurels thriving in what had become a neglected space.
When we installed a patio out back, the landscapers added lots of rich soil to the adjacent garden where there were rhodos. Most of the garden plants did fabulously well, but the rhodos all died within two years. A few years ago, in an effort to repopulate some of my lost rhodos, I planted one in a garden far from where the previous rhodos had been I was worried that the rhodos might have died from root fungus, so did not want to replant close to that site. The garden, of course, had amended soil.
The rhodo did not thrive; after the first year it started to drop leaves and eventually died. While we no longer have rhodos on our property, the azaleas and mountain laurels have continued to do fine in their original non-soil-amended sites.
I appreciate your comments on mulch—with all of our trees, the gardens get mulched naturally. Saves a lot of work and money! Hi Kathlin, Yours is a great observation that often, less is more. Trying to improve soil often ruins it. All too often supposed landscapers do not know what they are doing; those who claim that title should have to prove they know something about the trade.
Joan Kutcher said:. These are interesting observations. Hi Joan, yes the whole mycorrhizae topic is so important and its relationship to plants, especially those in the ericaceous adid loving family.
It might be a topic for an article in the future. NOTE for clarification: Mycorrhizae are beneficial fungi that are known to help many many plants, especially those in the ericaceous family. Jon from Kent, OH said:. Thanks for your insights! I just learned that here in Northeast Ohio, earthworms were wiped out by the glaciers about 11, years ago, so, for practical purposes, they are an invasive species! You nailed it perfectly with points 4 and 5 — oak leaves, and in my experience, birch leaves as well, tend to acidify soil in a mild, natural way.
Soil acidifiers in organic black soil may give the right overall pH, but will surely produce pockets or micro-zones of too much or too little acid,. There is nothing to hold onto, to stand up in, with soil that is too loose and friable. I am going to always think like a plant every spring! When I see gardens, nearly any garden, mulched with them, that garden is dramatically better than others. Me and my crew go and get them rescue them!
Glad you see the connection. Elizabeth Hayes said:. I found your article interesting with some surprising facts. Who would have thought that earthworms would be a problems for rhodos? I live in a house that is almost 80 years old and the landscape has rhodos that are at last 60 years old. My rhodos are leggy but they still produce blooms though not as many as I would like. I have asked experts but they tell me one cannot prune rhodos as old as mine to increase buds.
Is that true? Thank you for this insightful article. Hi Elizabeth, yes having oaks is always a good thing. As far as pruning old rhodos, it somewhat depends on the type they are and how leggy they are. If you want to send me a pic of them I can maybe give you a better idea. Jim Rodgers said:. Yes I agree whole heartedly with this ariticle. I my 40 years of exploring the Southeastern US I have notice the Rhodos evergreen and deciduous both not just growing, but rather thriving in leaf litter with thin sandy soils, often pure loose friable clay and then times rocky crevices.
The article is right on point and factual. I find most of what I was taught not just gardening but life in general a bunch of crappy lies or at a minimum untruths. Happy Gardening with Natives. Hi Jim, yes there is so much wrong info out there on something as basic as gardening. If i start a gardeners re-education camp here I will have you as one of the coaches.
Richard Perry said:. December 7, at am. Great article. I think one factor was overlooked though. I find that organic content, nutrient content, water permeation, and the like are typically addressed. What is not addressed are some of the mineral relationships.
Calcium and Magnesium in particular. I have found almost all the forest plants I grow do better if there is some Calcium and Magnesium added. I am curious about your thoughts. Clint Bancroft said:. December 7, at pm.
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