Pilchuck Pollinator

 

What you use for mulch is very important. The best materials are rather coarse and partially decomposed.  This partial decomposition usually takes a year or two. Fresh mulch materials will, of course, help provide a reserve water supply but the high level of bacterial action during decomposition will deprive your plants of nitrogen.  Fresh leaves and grass are particularly poor because they hold large amounts of water and deprive rhododendron roots of much needed oxygen.  Leaves should be piled and allowed to decompose for a year or two before using.  Any material that can become soggy and pack down, is a no-no because it, too, will cut off the oxygen supply.  Peat moss is particularly poor for mulching because it sheds water (instead of absorbing it) when it becomes dry. My favorite mulch is two year old wood chips.

How deep the mulch is is quite important because if it's too deep it also can reduce the oxygen supply.  The coarser a mulch material, the more of it that can be used safely.  However, about three inches of mulch around a plant should be sufficient.  Lastly, be careful to keep the mulch away from the trunk. If mulch becomes piled up around a rhododendron's trunk and keeps it wet above the soil line, deadly phytophthera fungi may invade and kill your plant.

Now, when was the last time you mulched your rhododendrons?  If it has been as many as two years, get out there and put another inch on this spring!  You'll be adding to the water reserves and also feeding the microorganisms that are important to root health.  Remember, poor, unhealthy roots are the first to become water stressed.