Tips for Beginners: Getting Started; Basic Information 101
When I first moved to the Seattle area, I had never seen a rhododendron before. The bold, bright flowers attracted my attention and required further investigation. I am sure many of you can relate to a similar experience. I have now lived in the Pacific Northwest for most of my adult life, 52 years to be exact, and have grown every species, hybrid, and cultivar of the genus
I could find. During that time, I have learned much about growing rhododendrons, mostly from the mistakes and failures I have experienced. I have read most of the books on rhododendrons and used the knowledge gained from expert plantsmen to quench my inexhaustible search for the "perfect rhododendron." I am still searching and find I am still a long way from having all the answers. That said, I have been asked to provide some basic information to help the novice rhodophile so you don't have to make the same mistakes I have.
There are at least two scenarios which we need to explore assuming little or no knowledge of the genus.
1. You are starting from scratch, moving into a new home with no landscaping.
2. You have a home with a few rhododendrons and you want to improve or expand your collection.
With either scenario, there are some basic facts that need to be considered:
There are many species of rhododendrons, nearly one thousand, and they have evolved in different climates, soils, and topographic variations. There are many places on this planet that rhododendrons do not exist and will not survive, and other places where some species will flourish while others will not. It may be challenging to try growing rhododendrons beyond their normal hardiness limitations, but doing so invites failures. So, let us start with scenario #1.
Before you purchase any rhododendron plants, do a survey of your neighborhood to determine what rhododendrons are growing there and how they are doing. Question your neighbors and ask about their experience and see for yourself which varieties look good and which ones are suffering. Be careful of purchasing plants from the "big box" stores. They purchase large quantities of plants from growers that raise them in controlled greenhouses and they may look good in the store but may not flourish in your location. It is best to buy them from a local grower or a specialty rhododendron nursery. If you see a good looking plant grown locally, it will most likely do well in your yard.
Before you dig the first hole, consider the site. Most rhododendrons will grow better in a semi shady location. As a general rule, the smaller the leaves the more sun exposure they will take. There are some exceptions to that rule, but the larger leafed plants will burn in a south or western exposure without some shade. Deep shade however will inhibit blooms. The ideal location gets morning sun and afternoon shade. Wind is another consideration; the larger leafed varieties will suffer from high winds while the smaller leafed varieties will do all right in some wind.
When you first plan a rhododendron garden it is common to place them too close together. Rhododendrons continue to grow and can easily double or triple their height and width in a few years. If you plant them on a 2-foot grid, just remember they may have to be moved in several years. If mature rhododendrons are planted too close, powdery mildew can be a problem. Good air circulation helps to deter fungi. Also consider the height if you are planting under a window. Rhododendrons can be pruned, but a large growing rhododendron will continue to grow and will eventually need to be pruned again. It is best to pick a dwarf or semi-dwarf rhododendron for that place under the window. Under the roof overhang is not an ideal place to plant a rhododendron; it will not benefit from the rain and the lime that leaches from the foundation will tend to counteract the acidity in the soil.
The condition of the soil will play a big part in your success growing rhododendrons. New house construction typically leaves the soil compacted and at best in poor condition. Some builders will bring in a thin layer of topsoil that looks good on the surface but may be hiding hardpan clay, sand, or construction debris. Rhododendrons require good drainage, slightly acidic and organic soil. Before planting, it is a good idea to test the soil for minerals, nutrients and for acidity. The local Extension Agent or a Master Gardener may be able to help determine the condition of your soil. Amending the planting area with compost or other organic matter before planting will pay off in happy rhododendrons. Refer to the American Rhododendron Society pamphlet "The Fundamentals of Rhododendron and Azalea Culture".
Scenario #2. You just moved into a home with some existing rhododendrons. If the previous owner or landscaper followed the advice above, you have a good start at enjoying your rhododendrons. However, there are some things you should consider to assure your rhododendrons continue to look good and flourish. What if the rhododendrons are not doing well or they are overcrowded, or in the wrong place? Mistakes in siting rhododendrons are common. Luckily, rhododendrons are relatively easy to move. They are shallow rooted and the root mass is dense so they hold together well. The best time to move them is in the fall after the weather has cooled down and the fall rains commence. They can also be moved in the spring before the new growth starts to emerge. Actually, they can be moved at any time in an emergency, but more attention is required to watering and cooling in hot temperatures.
If a plant looks really bad, perhaps you should just remove it and replace it with a more suitable specimen. You should not be responsible for other people's mistakes, and there are many of the new hybrids that outshine any of the so called "Old Standards."
Growing rhododendrons can be very rewarding and as you gain more experience you will surely want to expand your collection to include some of the species rhododendron that will grow in your area.
This is just a beginning to let you know how to start a meaningful journey growing rhododendrons. Stay tuned for detailed advice for the novice.
Bill Stipe is ARS District 2 Director
Vorhees, New Jersey
Many of us joined the American Rhododendron Society to learn about the basic cultural techniques, varieties, and all the information we could absorb on rhododendrons. However, we don't always get the basic information we need to have our favorite plant survive before and after we purchase it. I am writing this article to explain some of the basic information to help you get a good start and be successful in having a garden full of not only rhododendrons but other plants as well. I have been growing rhododendrons and azaleas for over forty years. I have made many mistakes, but being a member of the ARS, attending meetings and asking questions has helped me learn what to do and what not to do. However, I also learned that sometimes changing to a new way of doing things doesn't always work. So, "if you are doing something that works for you, don't make a change because you think you can do things better."
Planting and Care of Azaleas & Rhododendrons
1. Purchasing: When you are ready to purchase a plant, make sure that the plant has a hardiness rating that is compatible to the area you live in. Many plants may look good in color and leaf structure, but they will not survive the cold temperatures that are conducive to your area. Become familiar with the hardiness zone that you live in, and buy plants that are rated for that zone.
2. Water: Make sure that before planting the plant(s) you just purchased is (are) given a good drink when you get them home. Soak them in a bucket of water. This will enable the root ball to get rid of air and take up water. A lot of plants are grown in peat moss mixtures that dry out easily. Don't panic and feel that they have to be planted right away or they will die. If you keep the plant watered, it can stay in the pot or burlap for a long period of time.
3. Planting: Azaleas and rhododendrons can be easily planted and transplanted as they have compact and fibrous root systems. Spring and early fall planting is recommended as conditions permit. Again, after planting - water, water, water! If a plant is balled and burlapped when you purchase it, it should be planted without removing the burlap. The burlap should then be untied from around the stem of the plant and put into the soil. Any other type wrapping, plastic, etc., should be removed. The reason for not removing the burlap is so the roots won't be disturbed by the soil dropping off, etc. Most plants that you will buy are grown in containers or pots. When removing them from the container or pot, the root system should be broken apart or you can make 1-inch deep vertical slits spaced ½ inch around the root ball from the top of the root ball to the bottom. This is critical because the root structure of the plant has adapted to the container or pot and, even if planted, the root ball will continue to grow as if it were still in the container or pot. That's why it is critical to break up the root ball or cut slits in it. This doesn't pertain to plants that have their root balls wrapped in burlap. Azaleas and rhododendrons and many other plants cannot survive in "good topsoil." The soil that you have in your garden, be it clay, sand, or loamy top soil, should be used as a potting mix and have composted leaf mulch, garden compost or, the easiest to obtain, peat moss, mixed into it at the rate of 3-4 parts peat or compost to 1-2 parts soil. This will make a good potting mix that is aerated. The soil mix will hold the moisture and let the roots from the root ball move into the potting mix. How much water should I apply? Water just enough to keep the soil "moist," not "soupy."
4. Size of the Planting Hole: Neither azaleas nor rhododendrons require a deep hole. Planting too deep will smother the root system. Their rooting systems don't go deeper then 12–16 inches. This applies to mature plants. This is why they can be transplanted any time in their life. However, transplanting large mature plants can be cumbersome because of the size of the leaf system and of course the weight of the ball. An experienced person should only move large mature plants. The width of the hole should be at least 6–12 inches all the way around the ball of the plant.
5. Fertilizer: A good quality fertilizer specifically for azaleas and rhododendrons should be applied right after blooming. Never mix the fertilizer into the soil when planting as this could damage the roots. (Always sow on top using the rates suggested on the label.) Liquid fertilizers can be used. Make sure that the soil is wet/moist before applying liquid fertilizer. Water in after applying. Follow the rates suggested on the label. A good rule to follow: "less is better then more."
6. Pruning: Young azaleas and rhododendrons need to be pruned so they don't grow tall and leggy. Pruning also stimulates root growth. Pruning should be done right after blooming.
• Azaleas: Take at least 1 inch of last year's growth off. Azaleas can be cut/sheared anywhere on the stem. This will enable new growth to fill in the bare stems.
• Rhododendrons: Small leaf (lepidotes) can be pruned just like an azalea. Large leaf (elepidotes), have to be pruned back to where the new growth originated. This is called a node. If you just cut the stem in half, etc., the stem will die back to the node and the dead stem will have to be cut off. Make your cut approximately ¼ inch above the node. Taller, older, leggy plants can be pruned back by cutting back the hard wood at the rate of one-third the height of the plant a year. It will take older plants at least one growing season to grow new branches, etc. Pruning will encourage new growth to develop throughout the entire plant including the old hardwood. This pertains to young and old plants. Pruning stimulates root growth and keeps the plant bushy and prevents the plant from becoming leggy. A misconception that many novice gardeners have is that pruning will hurt or kill the plant. If you fall into this category, get rid of that "fear factor" and draw upon your confidence and "work" those pruning shears. Keep them sharp. Also, don't wait too long to do pruning - the earlier the better so that the new growth has a chance to harden off. To form buds, the new growth has to harden off. Buds form on new growth in July in zone 6. Check to see when buds form in your area.
Gardening and growing plants can be relaxing and fun, with minimum work. When planning your garden, try to have a plan in mind. Get to know what conditions plants like—sun, shade, etc. Some do better in sun while others do better in shade. Don't buy plants that look good in trade magazines. Always buy from quality local nurseries, garden centers or at plant sales that local ARS chapters have. Ask questions about hardiness, growing conditions, etc. If the person you are talking to doesn't know the answers, you may be in the wrong place. Make sure that your plants look good and are healthy. A lot of the big box stores have good prices to get you to buy, but they don't water or take care of the plants so sometimes you are getting a plant that isn't in the best condition. If you do buy a plant, make sure that it is not stressed from lack of water.
Ask questions, attend gardening courses given in your community and get involved with your ARS chapter's activities. All of these will help to increase your knowledge and you will have an excellent garden.
Good luck and happy growing!
Ted Stecki is ARS Eastern Vice President.