Rhododendrons & Azaleas
As spring draws near, gardeners start to wonder how their shrubs have made it through the winter, particularly their Rhododendrons. Did the buds set properly the previous fall? Did they have enough protection to prevent damage through the winter? Will they get any blooms this spring? Lots of questions, but the answer will only be told when rhododendrons blossom out, If they blossom out. Here's the info you need to ensure your Rhododendrons flourish.
Rhododendrons belong to the heath family (Ericaceae) which includes heaths and heathers, blueberries and mountain laurels. Most members of this family require a rather acid soil and good drainage. If you do not know what your soil type is, then it's best to purchase a
Soil Test Kit
so that you can amend your soil to the right ph for your rhododendrons and azaleas.
There is really not much of a distinction between rhododendrons and azaleas, they are both classed as rhododendron. The main difference is that most "azaleas" are deciduous, that is, they drop their leaves in fall, whereas most "rhododendrons" maintain their thick, leathery leaves through the winter.
Soil - Acid or Alkaline?
Soil preparation is perhaps the most important element to your rhododendrons health. The roots of Rhodo's and azaleas are shallow, quite delicate and easily damaged, so once you place them, it's best not to disturb them. Heavy or rocky soils that drain poorly will not be kind to your Rhodo's, so you'll have to ensure the site drains well, and the soil is amended. Rhododendrons prefer a soil PH of 4.5 to 6.
**If your soil PH is higher than 4.5, add sulfur or ferrous (iron) sulfate.
**If your soil PH is Lower than 4.5, add Lime (limestone powder or pellets).
Just follow the application instructions on the bags or containers that the lime comes in.
Shade or Sun?
Rhododendrons do better in milder climates that are slightly humid and prefer exposures that are north and east so it gets more shade than sun. South and Western exposures are usually too hot, dry and sunny. If you get just morning sun, or just late afternoon sun in a certain area then that would suit a Rhododendron fine, as long as it isn't getting dense shade. Filtered or dappled sunlight like you'd get from trees is actually preferable.
Hardy or Temperamental?
Also, avoid planting your rhododendrons in a wind path as it is more susceptible to wind scorch, which will split the leaves and perhaps even the bark. Certain corners of your house may create wind paths and you know you have one if you step around a corner and get blasted by the wind.
Pruning - Yes or No?
Pruning - when to and how to. When Do Azaleas and Rhododendrons Need To Be Pruned? Well, they can be pruned in winter or early spring. However pruning in the spring will prevent plants from producing many blooms, mainly because buds for the blooms set in late summer and early fall. The best time to prune rhododendrons and azaleas is just after their blooming period in spring. If you prune at this time, no additional pruning will be necessary. Make sure to make your cuts on a 45° angle.
Rhododendrons should be planted in either the Spring or Fall as these times give less stress to the shrub while it's settling in. You can plant in the Summer, but only if you keep it well watered and don't let it dry out. Dig the hole for your Rhododendron approximately TWICE the size of the root ball, in all directions (depth, width). Do Not cover the stem up, past the soil line it already had and in fact, if the root ball is left a little bit above the soil line, it won't hurt as long as you mulch well for winter.
A word of caution though concerning the root system. Rhododendron roots are shallow and need some air during the growing season. Do not mulch too heavily during the growing season, only enough to keep some moisture in and sunlight off the roots. Just before winter, mulch more heavily for protection. In the spring, pull most of the mulch away from around the roots, leaving a thinner layer, again, for moisture retention.
Moving or Transplanting
First of all, you should move your rhododendron/azalea when the plant is still dormant and free from stress. The best time is in the spring when the plant is still dormant but the soil is not frozen anymore. Moving a rhododendron when it is young is not a difficult job... just follow the planting instructions above. However, if your Rhodo is several years old, you will have a few more steps. As above, dig the hole twice as large as the root ball, ensure proper drainage and amend the soil to the proper ph, BEFORE digging up the plant (see *I recommend* below). Fill the bottom of the hole with a bit of amended soil so that the top of the root ball will be even with soil. Again, same as above, it doesn't hurt if the root ball is a little bit above the soil line.
When digging up the shrub, dig just inside the drip line. You will be cutting off the outside of the root system, but that is ok.. that is called root pruning, and it will actually stimulate root growth. Make sure the root ball does not fall apart, so perhaps use a burlap bag, or sheet of plastic to ease the plant onto when lifting and tie it up around the stem while moving it to it's new location.
It is not necessary to prune your rhododendron/azalea once transplanted but you may if you like... just not too drastically. Remember, the buds for the current years blooms were set the previous year, so if you prune after transplanting, you may be taking off the buds that would otherwise bloom. Remember, you can prune After the shrub blooms.
The thicker the mulch the better! Rhododendrons typically have shallow roots so you should mulch thickly to keep the moisture in and help it get through the winter. Pine and cedar needles, and shredded bark are ideal and a thickness of 2 to 3 inches is best.
Make sure that the plant (roots) are getting wet. Do NOT, I repeat, Do Not let the root ball of your Azaleas and Rhododendrons dry out. If this happens, then it can be extremely difficult to get it moist again, as the outside of the root ball can Shed the water rather than wick it into the core of the root where it is most needed.
Since rhododendrons and azaleas like a slightly acidic soil, you'll have to apply fertilizer that is specially formulated for these types of plants. Most garden centers have 'Azalea and Rhododendron' specific fertilizer and in fact, the box will likely say just that. If you cannot find rhododendron fertilizer locally, then here's where you can purchase it.
Gurney's Aluminum Sulfate - For acid-loving plants like azaleas, rhododendrons and blueberries. Work into soil at planting time, then again in spring, summer and fall -
** I recommend ** You can also purchase fertilizer that will not only feed your acid loving shrubs, but also amend the ph of your soil, at
For an assortment of Azalea Shrubs, go to
DirectGardening.com and click on the "shrub" link. Note: Use special coupon # G5666 for 3 free Peacock Orchid Bulbs with any purchase!
All in all, Rhododendrons and Azaleas are not hard to grow if you ensure they have the proper growing conditions. If truth be known, my own rhododendron is not in an ideal location, and the soil ph is higher than it should be, but it is still doing all right. When I get around to amending the soil and ensuring the poor thing has enough moisture, then it will probably Thrive and be even more beautiful!
Hmmm.... maybe I'll move it to it's own little spot in front of the house where it's a bit shady, and amend the soil only for it!