I wanted to grow azaleas twenty-two years ago when I returned to the Midwest after many years of enjoying the green-damp hills of Maryland. Most experienced St. Louis gardeners advised me to stick to iris and water-lilies. Those who had azaleas or had tried to grow them reported: “You can make them live, but the results will be poor.
We have practically no rain during July and August, and the relative humidity of 20% accompanies day temperatures of 100° to 110° degrees Fahrenheit to 25% percent.”
I bought two 24″ inch plants of Azalea Hinodegeri and used 1/3 sand, 1/3 peat, and 1/3 garden soil to fill a hole 30″ inches in diameter and 24″ inches deep for each plant. The soil was virtually 100 percent yellow clay.
First Azalea Bloom
The plants were set on the south side of my house, where they were protected after 2:00 P.M. from the western sun by high shade from oak trees. These plants lived and bloomed. They did not increase much in size during the next two years, but they did bloom well, and I have continued to grow azaleas ever since.
I read everything I could find about the needs of azaleas. I found, among other things, that they do not like much fertilizer but will thrive if given cottonseed or soybean meal each year as soon as they have flowered.
I was also interested in hearing what Missouri Botanical Garden had to say about mixing oak shavings with clay soil – a soil that tends to get a bit sticky when wet. They set some Mollis hybrid azaleas into this soil and added 4″ inches more of oak shavings as a mulch to conserve moisture and keep the roots as cool as possible.
Azalea In Every Season
I saw the plants about four months after being placed in the new environment. Though they had had very little water except the usual 3″ to 4″ inches per month rain we get in July and August, the plants had grown well and were well set with flower buds by late September.
I use equal parts of peat, sand, and soil mixed in beds 18″ inches deep, saving oak sawdust as a mulch since sawdust now costs approximately $5.00 per cubic yard. I have stopped planting azaleas in individual holes. I find it easier to get drainage from an excavation covering a large area than to put in drainage for many separate wells 30 inches in diameter and 24″ inches deep.
We must check the pH each spring and autumn to be sure it is between 4.5 and 5.5 because our public water supply has a pH of 9.3-9.7, but two pounds of copperas or ferrous sulfate per 100′ square feet of bed twice each year will be enough to offset the lime added with the county water.
During last year’s drought, when the temperature reached 113.6°, I found that simply spraying the leaves for a few minutes around 10:00, 2:00, and 4:00 was enough to keep the foliage from burning; that is when the mulch was already damp.
Some of my neighbors kept a continuous spray running because their beds became waterlogged, the plant roots couldn’t get air, and the leaves were yellow. Some of their plants died.
Of course, shade is a necessity in this area. 50% percent lath or high shade from hardwood, deep-rooted trees keep the plants happy. I screen my beds from severe winds too.
The roots are found mainly in the top 6″ inches of the bed. I add 8” to 10” inches of oak leaves to these beds each autumn and leave them throughout the summer, cautioning visitors against throwing cigarette butts on the mulch.
Varieties Of Azalea
What varieties thrive with this treatment in the vicinity of St. Louis? Many of the evergreen, dwarf Japanese Kurumes: Snow, Azalea Hinodegeri, Hino Crimson, Hino Mayo, as well as the tall-growing, deciduous Kaempferi hybrids which are primarily good pinks.
In addition, the Mollis hybrids, which grow from 3′ to 7′ feet tall, also do well for six to eight years but seem to run out after that. Their flowers of pale lemon-yellow to deep salmon-red will make 6″ to 8″ inch trusses of 2″ inch florets.
I am now experimenting with hybrids with more japonicum blood and believe they will be more resistant to heat. Others that furnish good blooms are some of the native azaleas from the Appalachian Mountains, such as Appalachian calendulacea and Appalachian arborescens.
44715 by C. Barbre