Water - Water!
George Clarke, Portland, Oregon
Reprinted from the Portland Chapter Newsletter
Here in the Pacific Northwest we tend to believe that in September we should bid summer adieu and prepare to welcome fall and winter. More often than not the long dry spell persists into fall, and the first rains are often insufficient to permeate the soil deeply.
This condition creates a dilemma that confronts most of us. It is whether or not to continue to irrigate our rhododendrons. There are two opposing viewpoints on the subject. One of our well-known authorities has advocated the withholding of water after August 1 in order to stop any further plant growth and allow the plants to harden-off for winter.
I disagree with this view point, feeling that while this may be prudent action in certain localities it does not apply here. During our prolonged period of rainless days, which in some years runs well into October, I urge that adequate watering be continued to provide for our plants a condition as nearly as possible like that found in their native rain-forest habitat. Those huge spring blossoms are formed in late summer, so give the plant all the raw material needed to do its job.
We should consider the individual plant and its growing environment. If planted in a water-retentive organic soil mix a rhododendron will need less water than if planted in a sharp drainage mix. One that is located in shade will lose less water than one in full sun. A well established plant will have a greater root system and get by with less irrigation. It is important to remember that a newly planted specimen must re-establish the capillary action between its root ball and the surrounding soil. One or even two years are required to create this relationship. During this period special attention should be paid to watering.
Another reason for ample fall watering is the advisability of taking your plants into freezing weather in as moist condition as possible. I have never forgotten the sight, years ago, of Mr. Lambert of Lambert Gardens out watering his plants like mad at the first indication of freezing weather. We have rarely lost any plants during periods of low temperatures and in large part I believe that this is due to following his example.
I think we all would agree that we should withhold fertilizer after mid June in order to avoid the stimulation of late growth, but withhold water, never!