More on Liming and Azaleas
Clarence Barbre, St. Louis, Mo.
Right now I want to say it seems to me that Mr. Alleyne Cook of Vancouver. B.C. has set up some excellent bait to get people to think a bit.* Here in the Midwest where corn is king it is a common practice to have soil accurately sampled and analyzed about every 4 years and then the kind and amount of fertilizer is often altered further by tissue tests made about August 1, on leaves just out, at about the time the plant is starting to mature its crop. I have little doubt that Mr. Cook has several soil analyses from good, fair and poor growing areas he can publish. If not he should consider getting them so as to confound his critics. I think it a good idea to hear from someone that does not follow at all times the accepted. I am presenting the following paper to the members.
Azalea Culture in the St. Louis Area
Shade especially from 1 p.m. to sunset is essential. Best is approximately 50% high shade of oak or other hardwood, deep rooted trees. Lacking that choose lower trees or shrubbery, preferably that of evergreens, as a background to the west. If natural shade is not immediately available, provide it with slat shelter or cheesecloth frame until permanent background plantings can be grown. Ornamental castor beans will provide excellent summer shade.
Preparation of Bed: Dig a trench 18" deep, 30" or more wide and long enough to allow 3' to 4' separation between the number of plants wanted. Cut a 6" wide ditch about 6" deep across one end of the bottom and fill it with water. If the water does not drain away within four hours install farm tile to provide necessary drainage. If natural deep drain age is good, wells 24" deep and 30" diameter will do for individual plants. Test for drainage by partly filling with water which must drain away in 1 hours or drainage is inadequate. Trenches are less likely, than separate holes, to become water logged in wet weather if drainage is poor.
Soil: Mix equal parts sand, brown peat moss, and soil in sufficient quantity to fill the trench or well and extend level 4" to 6" above surrounding area. pH must be between 4.5 and 5.5. Add one half cup of ferrous sulfate per 10 square feet of bed area, water well, wait 24 hours and test for pH. Repeat if necessary until pH is within range stated.
Planting: Set plants at same depth they were in nursery. Firm well but do not tramp or pack soil around plant. It should remain loose so air can enter freely.
Mulching: 8" of oak leaves or 2" of oak dust is best.
Fertilizing: Once each year right after flowering apply a handful of cotton seed or Soya bean meal as a very thin layer or use the special azalea fertilizer for this purpose. Place under the mulch but not into soil and water well.
Maintenance: When weather is hot, check need for water before adding. Soil beneath mulch needs to be damp not wet. Add mulch to maintain a 3 to 4 inch depth. Test each Fall for pH and add ferrous sulphate as needed to overcome high alkalinity of tap water used. Azaleas are not generally subject to attack by pests or diseases in this area. If humidity is low and temperatures are above 100° F. and soil is clamp, sprinkle azalea leaves early in morning and about sunset.
Varieties: Those found to do best in this climate are:
1. Evergreen dwarf Japanese Kurumes, 'Snow', 'Hinodegeri', 'Hino Crimson', and 'Coral Bells'.
2. Taller growing 'Kaempferi' hybrids which are mostly good pinks.
3. Mollis hybrids (deciduous) which grow from three to seven feet and have flowers ranging from pale lemon yellow to deep salmon red.
4. U. S. deciduous azaleas from the Appalachians, such as calendulaceum and roseum .
* Liming Rhododendrons by Alleyne Cook, A.R.S. Bulletin, April 1962.