I hope you have noticed the beautiful lavender flowers of the rhododendron shrubs that have been blooming for the last two weeks.
The variety is PJM, and these rhododendrons are broad-leaf evergreens, meaning that they do not drop their leaves in winter. This rhododendron grows to about 3 feet tall.
They prefer a slightly acidic soil, which is not what we have in this part of Minnesota, so amending the soil with peat moss when the shrub is planted will lower the soil ph enough to make the plants happy.
Most of our soil is heavy loam which can cause rhododendron roots to rot. A generous quantity of peat moss worked into the soil at planting time will help prevent this problem.
The potential for the foliage to winter-burn can be minimized by choosing a planting site in full to partial shade like the north, east, or west side of your house.
In the winter, broad-leafed evergreens planted in a sunny area can develop winter burn. This happens when their leaves warm enough to transpire moisture. The frozen ground prevents the plant from replacing the lost moisture, resulting in “burned” foliage. Some winters are worse than others for this problem, but avoiding winter sun is the best preventative.
PJM is probably the best variety for our area of zone 4. Several other varieties are listed as hardy but most of them have a much larger leaf, making them less likely to survive our harsh winters.
Other varieties bloom earlier in the spring, and in the case of a spring like we are experiencing this year, the flowers would likely have been ruined by the cold.