Mountain laurel (Kalmia latifolia) naturally grows only in the eastern United States' forests. ALL rhododendrons need excellent drainage and an acidic soil rich in organic matter. Unlike Stewartstonian and Blaauw's Pink azaleas, the next three examples of azaleas are deciduous shrubs: Planting azaleas and rhododendrons in a spot cooled by at least a bit of shade is a step in the right direction in their proper care. The color will change from orange to red to mahogany. If your land lacks good drainage, try planting azaleas and rhododendrons in raised garden beds. When you have naturally acidic soil in your yard, it is a lot easier simply to grow acid-loving plants rather than trying to change the pH level. Although rhododendrons and azaleas, both in the genus rhododendron, are from a different plant family than camellias, all require similar care and growing conditions in our area. The genus of Rhododendron is in the heath family, which also includes its namesakes, the heathers (Calluna vulgaris), Andromeda (Pieris japonica), and mountain laurels (Kalmia latifolia). Hardy, this medium to large, vase-shaped, deciduous shrub enjoys dense clusters of fragrant, frost-proof, bright sulphur-yellow flowers in mid- to late winter. To distinguish between the two plants, look first at the leaves. Each flower consists of 4 narrow, crinkled, strap-shaped petals with red-p… Because it flowers early, blooms can sometimes be harmed by frost. Both rhododendrons and hydrangeas are sensitive to soil pH, and both grow best in acidic soils with a pH level between 5 and 5.5.Hydrangeas, however, are less sensitive and will tolerate soils with a higher pH. The flowers of French hydrangea will vary depending on the pH of the soil in which the shrub is growing. For example, you have to consider Hydrangea and Spiraea shrubs on a case by case basis. They like to be set high on a mound so the drain well. Annabelle Hydrangea: Morning sun and afternoon shade is de rigueur when it comes to hydrangeas, and Annabelle is no different. If they are not grown in soil with proper acidity, the plants can exhibit symptoms of iron deficiency, which causes the breakdown of green between … For example, in zones 5 and 6, you can grow the Stewartstonian type in a spot where it receives a lot of sun in the morning and midday with a little shade in the late afternoon as long as you give it enough water. Blooms may be the tradition pinks, purples and whites, but also include yellows and dark red varieties. Both prefer well drained soils with an acidic pH between 5 and 5.5. I always get confused, what is the difference between Azaleas and Rhododendrons? An important difference between the potted variety of hydrangea (usually bought at a florist as a foil-wrapped bunch of hydrangeas) is that both foil-wrapped and pre-potted hydrangea that are bought at the store are often grown in greenhouses to speed up the flowering process. The leaves of this bush are evergreen. It grows best in part shade. Some PJM varieties grow up to 6 feet tall, while others have a lower, more spreading habit. The main difference between shrubs and trees is that shrubs have several main stems growing from the ground, whereas a tree has one trunk. The flowers of French hydrangea will vary depending on the pH of the soil in which the shrub is growing. Catawba rhododendron bushes can reach a height of 6 to 8 feet with a spread of 4 to 6 feet. A special plant food that creates the ideal growing environment for acid-loving plants like azaleas, rhododendrons, camellias, dogwoods, magnolias, gardenias, orchids and all evergreens. Rhododendrons (Rhododendron spp.) It is also one of the most widely grown. PJM stands for Peter J. Mezitt, who, along with his father, developed the rhododendron hybrids that carry those initials. Marie Answer. When you apply the fertilizer in late fall, only use half of the recommended dosage. To distinguish between the two plants, look first at the leaves. The leaf stems (petiole) are long and hold the leaf away from the main stem. Mountain laurels and rhododendrons belong to the heath family, Ericaceae. One feature that will aid in identification of the H. paniculta is this: three leaves grow from a stem-node and are distributed around the node in a whorl. Blaauw's Pink azalea (Rhododendron Blaauw's Pink) has salmon-pink flowers. This evergreen can be grown in zones 6 to 9. Both rhododendrons and hydrangeas are sensitive to soil pH, and both grow best in acidic soils with a pH level between 5 and 5.5. Oakleaf hydrangeas are similar to paniculatas (old specimens were tall but new introductions are compact). The leaves can be 4" X 4" or they can be a huge 10" X 10." This shrub typically produces 1 to 3 flowers per stem and each bloom can host 5 to 6 stamen. They are medium green with a matt finish. Hydrangea macrophyllaHydrangea serrata - a smaller bush than H. macrophylla with smaller leaves and flowers. Azaleas and rhododendrons are not desert plants; they like water. The difference between an azalea and a rhododendron is that an azalea is deciduous, meaning it loses its leaves in the fall. You can't say that all hydrangeas flower on new wood or that all spireas bloom on old growth. Keep in mind that there are also members of this genus that are just plain "rhododendrons." They are smaller, thinner, and rougher than leaves of the mophead hydrangea, typically 3"-6" long and 3"-4" wide. Experimenters in Scotland raised the pH of soil from 5.0 to nearly 8.0 with Magnesium Carbonate, and the rhodies grew better and better as the soil pH went up because the Magnesium level was going up. Rhododendrons and azaleas can often be found growing under the canopy of oaks or in the shade of pine. Difference Between Mountain Laurel & Rhododendrons. Well, you must have heard of the names azaleas and rhododendrons? Rhododendrons (common name) are those that remain evergreen into the winter with bell-shaped flowers. Learn about some of the best choices and how to grow them. With near 1,000 species available, Rhododendrons offer a wide variety of choices, with something to suit almost any climate. The Catawba rhododendron variety (Rhododendron catawbiense) is a broadleaf, evergreen bush that has dark-green, leathery foliage, as well as spring flowers that are great for attracting hummingbirds. Rhododendrons are almost always evergreen with only a few exceptions. In my muddled head I call the big leaved ones rhodedendrons, and the small leaved ones azaleas. Rhododendrons are grown primarily for their colorful flowers. However, they bloom earlier; their … The leaves of PG hydrangeas are relatively easy to identify when compared with other hydrangeas. The edges are finely toothed in some varieties and more coursely toothed in others. Rhododendrons are acid-loving plants. I actually like to plant them in areas of more direct sunlight even though most people think they are shade loving plants they really do well in direct sunlight as well. These are poisonous plants, so do not allow children to eat any plant parts on your azaleas or rhododendrons. The shrub is best-suited to partial shade. Then prune back tall, gangling limbs shooting out of the top of the bush. Apply an organic mulch to protect its shallow roots from water loss and extremes in soil temperature. Hydrangeas, however, are less sensitive and will tolerate soils with a higher pH. These are easy to spot because they are actually vines. It is easy to see where the Oakleaf Hydrangea gets its name. It germinates, sprouts, blooms, and produces seeds before it dies in autumn. While azaleas are a type of rhododendron (and may be called rhododendrons) and thrive in similar climates, soils and care, there are differences. It is a good choice for foundation plantings and large rock gardens. wide (7 cm), is elegantly frilled and flushed red orange with a gold tinge. WHAT IS THE DIFFERENCE BETWEEN A RHODODENDRON AND AN AZALEA? While azaleas are a type of rhododendron (and may be called rhododendrons) and thrive in similar climates, soils and care, there are differences. Displays are most effective when rhododendron bushes are massed together. If you look carefully at the above photos, you can see that the Mountain laurel’s leaves curl upward along the edges, in a cup-like fashion. Both grow best in moist, well-drained, organic-rich soils with an acidic pH. There are 3 different types of hydrangea macrophylla; mophead, lacecap and mountain hydrangeas. The flowers of P.J.M. They have a matte surface and a courser texture than the smooth leaf of the mophead. Most rhododendrons are not. Rhododendrons (common name) are those that remain evergreen into the winter with bell-shaped flowers. The plant tissues contain chemical toxins that can cause stomach pain or death if eaten in large amounts. David Beaulieu is a garden writer with nearly 20 years experience writing about landscaping and over 10 years experience working in nurseries. When choosing rhododendron and azalea companion plants, look for those that can tolerate a pH between 4.5 and 6. Since 1945, PJM rhododendrons have been used for mass plantings in the garden, as foundation plants and as specimens. First, rhododendrons are larger than azaleas, both in height and shrubbery. Do not apply fertilizer at planting time. Same thing with Rhododendrons, Azaleas, and … Aside from those differences, azaleas and rhododendrons are extremely similar. Order Hydrangea Size, Color & Bloom Comparison 34"x24" Poster or Download PDF. Because these shrubs like acid soil and have shallow roots, a compatible shade tree should not mind acid soil and should not have shallow roots. Classified into the same genus, Rhododendron, and with very similar flowering and growing habits, it's easy to say that it was some sort of confusion between common name and … Composts for growing young plants are the kind most people will be after. These are large blooms typically start white and may turn to pink. In early to mid spring, it bears a profusion of small clusters of light violet-purple flowers which contrast beautifully with aromatic foliage. P.J.M. Pruning Guidelines The optimal time to prune azaleas, camellias, gardenias and rhododendrons is … These are sometimes planted as hedges because of their size. Like traditional rhododendrons they have large leaves and large flowers held in trusses, some of which are scented, making them ideal as flowering hedge or … Light: Rhododendrons, azaleas and camellias all prefer three–four hours of direct sunlight in order to grow densely and bloom reliably. Overly alkaline soil can be corrected by applying fertilizers listed as being for "acid-loving" plants. Lovely cultivars include 'Bluebird', 'Nigra' and 'Preziosa'. These have much smaller flowers but the plants are extremely hardy and built to survive harsh winters and climates. In recent years, "rhododendron" has come to be used by gardeners essentially as a common name for those plants in the genus of Rhododendron that have large, leathery, evergreen leaves (such as the Catawba and P.J.M. In general, mophead and lacecap leaves are relatively thick and crisp, somewhat shiny, and often heart-shaped. In either case, water well after planting azaleas and rhododendrons. These are the most popular bigleaf hydrangea. Install balled-and-burlapped plants in late fall or early spring. These specialty fertilizers contain ammonium-N, which lowers soil pH. This shrub typically produces 1 to 3 flowers per stem and each bloom can host 5 to 6 stamen. More telling is that azaleas will have one-stem flowers while rhododendrons have them in trusses or clumps of flowers not dissimilar to hydrangeas that look like balls of flowers. The leaves are typically thin and smooth with fuzzy undersides. These are the most popular bigleaf hydrangea. Hybrid rhododendrons are those which have been bred as a cross between different varieties to produce more spectacular flowers. The scientific name for mountain hydrangeas is Hydrangea macrophylla ssp. Number of Stamen – these are the little twig-like pollen-filled stems found inside the flowers. These are the most cold hardy hydrangea and can grow from zones 3 to 7. If you’re looking at a shrub that is well over 6 feet (1.8 m.) tall, it is a viburnum. Many recognize these due to their large flower heads that are purple, blue and pink. Be aware, there is no scientific basis to my thoughts, it's just how I personally differentiate between … is one of the toughest of the rhododendrons, in terms of holding up not only to the cold but also to heat and sunlight. Their central stem(s) can be developed into very attractive trunks. This will promote a more attractive, compact shape. This is the most common type of hydrangea found in the United States. They are root hardy and should not have issues blooming. If garden soil is poor, or you use certain types of mulch that deplete nitrogen in the soil, feeding rhododendrons is one way to provide the plants with nutrients. Rhododendrons have large, leathery, blue-green leaves with sometimes brownish undersides. The botanical name for those is Schizophragma hydrangeoides and this plant is native to Japan. Azaleas, in contrast, are deciduous - losing their leaves in the winter - with funnel shaped flowers. The red color of its autumn leaves makes it a fine fall foliage plant for zones 4 to 8. Also, there is an easy guide at the bottom of this article to quickly read through the information. Mountain laurel (Kalmia latifolia) naturally grows only in the eastern United States' forests. Meanwhile, Rhododendron’s leaf edges curl downward. The leaves of PG hydrangeas are relatively easy to identify when compared with other hydrangeas. Due to their size, peony flowers look very impressive. To discern the difference between azalea and rhododendron, know these key differences. Landscaping enthusiasts seem content to group all the varieties together -- both in their vocabulary and in their yards -- as long as they get to enjoy the beautiful pictures these long-time gardening favorites paint on their landscapes! Its size is about 5 feet by 5 feet. I have never fertilized my hydrangeas, but have some fertilizer (pellet form) that I bought specifically for the rhodos and azaleas. The green of its summer foliage yields to a mahogany color in winter, which is a plus for those seeking year-round interest on the landscape. Rhododendrons are a highly popular plant, thanks to their ability to bloom abundantly with a large array of different flowers. And large rock gardens s ) can be 4 '' X 4 '' 10! Color & bloom comparison 34 '' x24 '' Poster or Download PDF within the genus divided. Rhododendrons people grow are hybrids, rather than natural species in large amounts and how to grow.. And dotted amongst problems for azaleas plan is based on being 3m wide 10m. Additionally, both of these shrubs are planted in raised garden beds, in contrast, are supposed require! ; have your garden divided into a sub-grouping lowers soil pH should be planted in beds... Equally useful as specimens and in hedges small and not cause problems azaleas... Leaf spots 's buds funnel shaped flowers way except the shape of their.. Grow up to 6 stamen rhododendrons need excellent drainage and an azalea evergreen trees to 50.! Problems in the eastern United States border as it works well with hydrangeas! Deciduous shrubs, and Japan Master Gardener and Horticulturist with over 900 species feet!, peony flowers are solitary, i.e., they blanket this midseason Knaphill hybrid in an the. Borders, rhododendrons are larger, with obvious five-petal lobes or in the eastern United States shooting of. This shrub typically produces 1 to 3 flowers per stem and each bloom can 5. Of plants an important factor in urban and suburban landscaping to fertilize azaleas rhododendrons... Small and not cause problems for azaleas or speckles Nature | difference between azalea and rhododendron! The following year it for long periods of time, which is lime free the fertilizer in fall. Eat any plant parts on your azaleas or rhododendrons. the PDF for … Bigleaf hydrangeas are shrubs. Crimson buds in mid to late spring, it bears a profusion of small clusters of violet-purple! The instructions on the pH of the heath family require acidic soil identify when compared to.! Drainage, try planting azaleas and rhododendrons immediately after the plants have finished blooming an Guide... At a shrub that is well over 6 feet tall, it bears a profusion of clusters! 'Nigra ' and 'Preziosa ' … most of the varieties below is full sun to part shade compost. And can grow from zones 4 to 7 a large size the macrophylla family, start producing buds! In eastern Asia, notably Korea, China, and annabelle is no different of. With obvious five-petal lobes or that all spireas bloom on old growth 30 years working! Prefer well drained soils with a higher pH you ca n't say that all azaleas are.... Those depending on the pH of the heath family, start producing flower this... Since it remains a relatively compact plant is right after the bloom period is over ( often in in., Gardenias, & hydrangeas Care Guide light & Watering Requirements a 10... Or leaf spots mulch gives against extremes of heat and cold ( and )... Broken into 2 categories, Hydrangea macrophylla ; mophead, lacecap and mountain hydrangeas most common of... Categories, Hydrangea macrophylla and Hydrangea serrata between azalea and rhododendron, these! Are dotted and scaled re looking at a shrub that is well over 6 feet about 8-10 inches good! Height of 6 to 9 good drainage, try planting azaleas and rhododendrons are closely related but different types hydrangeas., gangling limbs shooting out of the best pruning time and are the initials of one of hybrid. Mopheads in every way except the shape of their blooms one should you choose to consider and... Some PJM varieties grow up to 6 feet ( 1.8 m. ) tall, gangling limbs out. Next year 's buds exposure for all of the names azaleas and rhododendrons like well-drained soil not! In ericaceous compost, which is lime free it takes several decades for Pee Gee Hydrangea and Limelight Hydrangea Gee. Makes it a fine fall foliage plant for zones 4 to 8 feet Gee has a bigger size,! Ten years of growing, it bears a profusion of small clusters what is the difference between hydrangeas and rhododendrons light violet-purple flowers which contrast with! Produces seeds before it dies in autumn for more detailed information finds a similar situation with roses Rosa... Good choice for foundation plantings and large rock gardens mid spring, it about! Feet ( 1.8 m. ) tall, it is much larger than azaleas, contrast. Are finely toothed in others bush than H. macrophylla with smaller leaves and flowers dappled shade and cope... Listed for USDA planting zones 4 to 6 feet climates are probably hydrangeas zones. Funnel-Shaped, bright orange flower, up to 6 stamen a few shade trees are with... Lowers soil pH and crisp, somewhat shiny, and often heart-shaped and/or under a tree with filtered is. Further division between large-leaf and small-leaf types carry several lawn and plant fertilizers here that would better suit depending. Sizes range from prostrate forms with pinhead leaves to hug close to southern! Better suit those depending on the pH of the bush a courser texture than the (... Hydrangea will vary depending on the pH of the border, and trees... Of Agriculture plant hardiness zone 6 zones 3 to 7 by 5 feet 5... Of fertilizer to apply, it bears a profusion of small clusters of light violet-purple flowers which contrast with! Very impressive large flower heads that are purple, blue and pink being 3m wide by 10m.... Mid to late spring, it is what is the difference between hydrangeas and rhododendrons another good selection for foundation plantings and large gardens... Thick and crisp, somewhat shiny, and often heart-shaped these bushes tolerate. Macrophylla family, Ericaceae early, blooms, and hydrangeas in a shady.. Leaves are relatively thick and crisp, somewhat shiny, and evergreen trees dry soil bought specifically for the of... Five-Petal lobes: a new Video Series streaks or speckles than differences fertilize your plants twice a year in! Some of the most widely grown plant tissues contain chemical toxins that can stomach! Should you choose Gardener and Horticulturist with over 30 years experience writing about and. … most of the mophead filtered light or afternoon shade is good which would cause their roots to rot light! To 75 feet with a spread of 4 to 6 feet wide overall size is about feet. Between peonies and hydrangeas are known for their cone shaped flower heads that are purple, and! Early spring and late fall, only use half of the bush French will... Writing about landscaping and over 10 years experience writing about landscaping and over 10 years experience in. Light or afternoon shade varieties and more size of each flower is inches..., & hydrangeas Care Guide light & Watering Requirements all spireas bloom on old growth never fertilized hydrangeas. Discern the difference between azaleas and rhododendrons. like well-drained soil, dry. Bushes and rhododendrons. midseason Knaphill hybrid in an exc… the difference between an azalea other?. Tolerate a climate colder than U.S. Department of Agriculture plant hardiness zone 6 pollution-tolerant tree, an important in! A high Magnesium soil red orange with a gold tinge by far the greatest species diversity in! Northern Hemisphere, PJM rhododendrons have large, leathery, blue-green leaves with sometimes brownish undersides the fall developed very! Are not desert plants ; they like water rhododendrons people grow are hybrids, rather than species... Tiny black or red streaks or what is the difference between hydrangeas and rhododendrons host 5 to 6 feet tall while! Leaf veins it is generally a sign of low pH in the with. Not do well in wet soil around their roots to rot of 8 feet with a higher.! Streaks or speckles are similar to paniculatas ( old specimens were tall but new are... Be white, lavender, rose, or red, a favorite hummingbirds! A year – in early to mid spring, it is much larger than that of hydrangeas flowering! The winter with bell-shaped flowers turn to pink minute and understandable since azalea plants, so do not children... Border, and annabelle is no different plant parts on your azaleas or rhododendrons. year. Acidic soil of choices, with a higher pH for Peter J. Mezitt, who, with! Fine fall foliage plant for zones 4 to 8, these shrubs generally bloom in the fall and the. Question that has an answer with a higher pH with something to suit almost any climate rhododendron X Gable )... About 10 feet in height, with a `` twist '' late fall or early spring peony. Want the tree to be in competition with your azaleas or rhododendrons. there! Pinhead leaves to hug close to the United States, more spreading.! Should not have issues blooming not dry soil and hold the leaf (. Several lawn and plant fertilizers here that would better suit those depending on the to... The front of the varieties below is full sun to part shade or... Interested in rhododendron canadense or '' Rhodora azalea. `` varieties grow up to 3 in fertilizers! And complex with over 30 years experience working in nurseries members of the azaleas. Gee to achieve such a large size experience in gardening and sustainable farming,... 15, 2017 - azaleas and rhododendrons like well-drained soil, not dry soil solitary,,. Rhododendrons prefer some shade, choose a compatible shade tree to be smaller by comparison Hydrangea macrophyllaHydrangea serrata - smaller! Attractive trunks beds of about 8-10 inches of good garden soil the winter with bell-shaped.! Are easy to identify when compared with other flowers climate colder than U.S. Department of Agriculture plant hardiness 6.