Rhododendron is a genus of shrubs and small to (rarely) large trees, the smallest species growing to 10–100 cm (4–40 in) tall, and the largest, R. protistum var.
First off, the flowers of many rhododendron and azalea plants are chock full of nectar. When in bloom, these shrubs are like neighborhood fueling stations for bumble bees.
Rhododendrons are perfect spring-flowering plants for brightening up shady gardens. They succeed in partial or moderate (but not full) shade while azaleas – part of the rhododendron group – will thrive providing they get at least 4 hours or more of direct sun per day.
The rhododendron whitefly is mainly an aesthetic pest, although heavy infestations can damage susceptible plants. Biology and life history The insect overwinters as a nymph. There are several species of whiteflies. Some overwinter as adults on the undersides of evergreen leaves (salal, Oregon grape, rhododendron).
Some varieties naturally have a rounded, ball-shaped plant habit, others are open and spreading, while other rhododendrons have an upright growth habit. If they are not placed with height in mind the taller growing plants can shade out the shorter plants.
Best Time for Trimming Rhododendrons According to most professional landscapers, the ideal time for pruning rhododendrons is late winter, while the plant is dormant. However, any time between the first frost in fall and the last frost in spring (while the sap is low) will Read more
A: The usual suspects when rhododendrons fail to bloom are dense shade, drought or overfertilization. In spring, the plants use large amounts of water for new growth and flowers. Since their evergreen leaves can create an umbrella that sheds the rain, the poor plant's rootball Read more
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.
Rhododendron roots require a high oxygen level (that's probably why they are shallow rooted) and an organic soil that supports mycorrhizae (the fungus that invades their roots and promotes their growth).
A leggy rhododendron is one that has not received proper maintenance pruning. This type of pruning involves removing faded flower clusters to prevent seed formation. This is a once-a-year chore and shouldn't take very long. It's best accomplished after flowers have wilted and before new Read more
Along with butterflies and bees, ants carry pollen. This is a mutually beneficial relationship, a symbiosis; the ants eat the honeydew trails, helping both the rhododendron and the ant colony. This balance is a sign of a healthy ecosystem in the garden.
Overwatering does in about 75 percent of all rhododendrons purchased every year, the American Rhododendron Society notes. These statistics are intimately linked to the plant's requirement for well-drained soil and distaste for wet feet. Properly irrigating your plants requires resolving drainage issues as well.
The reason for rhododendrons not flowering are because of pruning the wrong time of year, frosts damage to the developing flower buds, drought, alkaline soils too much nitrogen fertilizer or a lack of sunlight. A late frost can damage flower buds (which turn brown) and Read more
Mulching: Rhododendrons do best when they have about a 2" to 3" layer of mulch to hold in moisture, prevent weeds, and keep the roots cool. A year-round mulch will also provide natural nutrients and will help keep the soil cool and moist.
Unlike deep-rooting shrubs such as yews, rhododendrons' and azaleas' roots run relatively close to the surface, usually within the top 12 inches of soil. They also have a vertical root structure from the center of the shrub which plunges the same depth or deeper, but Read more
When air temperatures go above 95°F (or even lower for alpine types), rhododendrons and azaleas appreciate a misting to prevent desiccation of their foliage.
Rhododendron simsii in bloom provide two to four weeks of beauty. Houseplant care: These hybrid forms are usually grown indoors for a single season as temporary winter and early spring flowering plants, but it is possible to keep them alive and attractive for several years Read more
Controlling Ants Excluding ants from the canopy of a rhododendron can be tricky, but you can place sugar-based baits around the base of the plant to encourage them to stop short and feed. Check the baits frequently to ensure that they remain full while you Read more
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 4.5–6).
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 Read more
The leaves of your Rhododendron plants can turn brown if they are kept under direct sunlight. This is because they can also suffer from drought symptoms, even if the plant is being watered regularly. But generally, Rhododendron plants are recommended to be kept away from Read more
Some rhododendrons can be espaliered (trained to grow with the branches growing horizontally against a wall, fence or trellis) or grown in movable tubs. Oaks and pines are the most commonly mentioned companions for this beautiful shrub.
Popular plants such as azaleas, rhododendrons, blueberries, strawberries and heathers, are all acid-loving, meaning they need a soil pH of about 5.5. Knowing whether your soil is acidic or not is the first step to healthier plants season after season.
Root & Crown Rot. The fungus Phytophthora species causes one of the most common disease problems in the landscape for rhododendron and azalea. This fungus is a “water mold,” and thrives in poorly drained or wet conditions. A wilted plant is usually the first sign Read more
All parts of the rhododendron plant are toxic for dogs. Symptoms include gastrointestinal upset followed by weakness, paralysis, and abnormal heart rhythms. Large doses can be fatal.
In general, it's common for most species (including hybrids) of rhododendrons and azaleas, to bloom in the springtime. However, certain species can bloom throughout the summer into the fall and even the winter. These can change depending on the climate in which the rhododendrons are Read more
It stands to reason that evergreens, like rhododendrons, can handle a tough winter without much help, but the fact is that even sturdy plants get the blues when it's cold. Winter damage of rhododendrons is a very common problem that causes a lot of distress Read more
Rhododendrons and azaleas are susceptible to a fungal wilt disease called Phytophthora root rot. The Phytophthora fungus enters the roots of the plant from infested soil and clogs the water-conducting vessels of the plant. Symptoms include poor growth, rolling of leaves, and the eventual death Read more
Rhododendron is a genus of shrubs and small to (rarely) large trees, the smallest species growing to 10–100 cm (4–40 in) tall, and the largest, R. There are alpine species with small flowers and small leaves, and tropical species such as section Vireya that often Read more
At planting time, use 10-10-6 fertilizer before you water the plant in. In early spring, the rhododendron buds swell. At this time, apply a complete 10-8-6 fertilizer. Apply another light dose of this fertilizer when the leaves emerge.
Best Fertilizer for Rhododendrons If you have planted your shrubs in fertile soil, fertilizing rhododendrons is not a necessity. You only need this if your soil is not sufficiently acidic for the plants. Plants generally require three nutrients to thrive: nitrogen, phosphorus, and potassium.
For example, you'll want to make sure that their soil is moist enough, which means regularly watering it, even if you do live in a humid, moist climate. While you don't want to drown these plants, providing them with enough moisture is essential for making Read more
Some foliage droop is normal in dry weather, especially on warm afternoons, but when leaves still show signs of drooping in early morning, the plant is showing a need for water and should be irrigated.
Rhododendron. All parts of a rhododendron bush, including the leaves, stems and blooms, are toxic to both cats and dogs. Only a small amount of rhododendron is needed to cause health problems. Smaller dogs will typically experience more severe, toxic effects than large dogs after Read more
Choose a site with dappled shade in sheltered conditions. Avoid deep shade beneath other trees. Most rhododendrons will tolerate a more open site if sheltered from cold, drying winds. Dwarf alpine species will tolerate full sun provided the soil does not dry out.
Rhododendrons grow best in soils with a pH of 4.5-6.0. They do not grow well in soils with appreciable levels of calcium. This is principally due to iron getting 'locked up' and becoming unavailable to the plant. Soil pH is easily measured using a home Read more
In general, rhododendrons need supplemental water during our dry months. Once every three to four weeks generally works well. The root zone should be moist to at least 8 inches deep.
When to Plant Rhododendron Plant the rhododendron bush in spring when danger of frost has passed. Plant the bush high in properly prepared soil, as soggy and waterlogged roots are the main cause of plant failure in the landscape.
Several people have expressed alarm at the drooping leaves on their rhododendrons during the recent cold weather. This is most pronounced on the rhododendron varieties with thick, waxy leaves. The bending down is a result of a natural response to temperature — or thermotropic movement.
Rhododendrons are not highly susceptible to insect pests, but they are occasionally beset by rhododendron borers, rhododendron lace bugs, and two kinds of weevils. Weevils – Leaves notched on margin, sometimes wilting during hot weather; eventually heavily infested plants may die.