Protect rhododendrons carefully during mixed weather conditions

Posted: Wednesday, May 22, 2002

The last I wrote about rhododendrons, I got inquiries about what to do about damages done by spring's dry, bright days and bitterly cold nights. Effects ranged from dehydration causing leaf scorch to total desiccation leaving no greenery at all. People tell of beloved specimens 15 or 20 years old, the focus of their landscape and treasure of their property, being withered and looking dead.

David Lendrum is a master gardener and owner of Landscape Alaska. Responses or questions can be sent to

Don't be in too much of a hurry to pull them out. It may be that the plant has sacrificed leaves while remaining alive and will be able to grow a new set. This strategy has allowed rhododendron to survive the millennia; it can't be the first time they have faced cold nights and dry days.

To tell if a plant has entered the vale of death, or is just waiting to put out new foliage, take a small sharp blade, or a strong fingernail, and scratch through the bark on a few branches. If the layer right under the outer bark, and just outside the woody core, is green, the branch is still with us and has the potential of regrowth.

If it's brown or dry, scratch lower on the branch, even down on the trunk. The genus rhododendron is amazingly adaptable, and really tough. It can sprout new growth anywhere on the branch, so the presence of obvious growth buds is no indicator.

If green is detected, or if one is unsure if the plant is dead, watering is the first step. Encourage new growth by rehydrating the ground, by sprinkling and irrigating, and then a day or two later do it again.

When soils dry out, they are difficult to rewet, the surface absorbs as much as it can, and then the rest washes away, running off and carrying with it the loose soil particles. When we water dry plantings, we give enough water to moisten the soil, and when puddling begins, we stop.

After the water has soaked in, and a few hours more, we can give it another drink. The water has soaked deeper into the earth, and the surface is in a state to receive another dose, slightly larger this time since the capillary action of the soil mass has been recharged.

Don't fertilize the damaged plants until they have been well watered. Fertilizers, even diluted liquid forms, are salts, and their first action is to cause an outward pressure on the plants cell walls, like a thirsty person drinking salt water.

If your rhodies look all right, or the damaged portion is small, go right into normal spring feeding after you get the soils good and wet,. If you have lost most of the foliage, wait for the new leaves to emerge.

A couple of weeks are sufficient to tell if death or disfigurement is the result, but that does not mean do nothing during that time. Remove the most damaged leaves with sharp pruners, the kind like scissors where the blades pass one another, cut the little stem that hooks the leaf to the branch, and step back for a look. If the result looks better, and the remaining foliage looks OK, go on to other tasks.

If it looks bad, and you are ready to pull the plug, do so with no compunction. The whole reason we garden is self-centered; we please ourselves by surrounding ourselves with beauty.

When the beauty is gone, we replace it with something more pleasing. The less desirable plant can be relocated to another place in the yard or passed into the great compost pile in the sky. There are lots of rhododendrons in the world, and there are many new types that you might like even better.

The Yakusamanim hybrids (called Yaks) are delightful, and during the late unpleasantness, didn't suffer any of the damage done to the older types. They are smaller growers, getting 3 or 4 feet tall and 5 feet across in 20 years, and the flower concentration is huge. Yaku Princess is blooming now at the nursery, and she has beautiful pale pink blossoms on a sturdy workhorse frame.

The leaves are deep lettuce green, and the underside shows the fuzzy layer common to her race. This fur traps moisture during the coldest weather, keeping the atmosphere right around the leaf openings wetter and less prone to drying out. That's why she was able to take the harsh spring without damage. She will succeed where others have failed.

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