soil which is acid or which can be acidified. In soils which are not 
quite acid enough, ammonium sulphate, properly used, will increase 
the acidity of the soil and also provide a good source of nitrogen. On 
soils which are near the neutral point it would probably be desirable 
to acidify with sulphur. 
Rhododenrons normally require a considerable amount of organ- 
ic matter in the soil. This may be added in the form of peat moss, 
leaf mold, sawdust or well-rotted manure. Where sawdust is 
used, cr for that maitetr where any other dry organic matter 
which has only started to decay is applied, it will be necessary to 
add additional nitrogen. Usually at least twice as much nitrogen 
will be needed for soil which has had sawdust worked into it, or 
applied as a mulch, as would be needed if the sawdust were not 
used. When planting in heavy soil mix peat moss or leaf mold 
with the soil to be filled in around the plant. Set the plants 
about an inch deeper than they grew in the nursery. More and more, 
Rhododendron growers are using a mulch of peat moss, sawdust, 
leaves, or other organic matter. This keeps the soil cooler in Sum- 
mer, conserves moisture, and of course adds organic matter as it 
decays, besides providing some protection against Winter injury 
of the base of the trunk and the roots. To be satisfactory a mulch 
should be deep enough to prevent the growth of most weeds. In very 
dry periods it will be advisable to check the moisture under the 
mulch and perhaps apply additional water. Rhododendrons are 
rather sensitive to dry weather and ample watering is advisable. 
Rhododendrons are often said to be shade plants but they do not 
like heavy shade, especially under trees where there is competition 
with the trees for water and plant food. The north side of a build- 
ing where the Rododendrons may get a little direct sun in morning 
and evening, is a very desirable location. Certain small trees 
providing light shade may be the best where there is ample moisture 
and plant food. Where the soil is very dry and where competition 
with trees would be a serious factor, it may be practical to build 
a lath shade. In warm climates, lath houses provide a pleasant 
place for the gardener to work and to enjoy the Rhododendrons 
as well as giving them the conditions they require. Lath houses 
may be constructed fairly cheaply and if well designed and well 
located, they can be an asset to the garden. 
Rhododendrons require about as much fertility as other garden 
plants. The fertilizer, of course, should not contain lime, as lime 
is definitely undesirable for Rhododendrons except under extremely 
acid conditions. 
Azaleas, as a group, are somewhat more tolerant of direct sunshine, 
higher Summer temperatures, and drier conditions than are Rhodo- 
dendrons. 
