April is rhododendron season here on the North Coast, a time when the sleepy, quiet shrubs suddenly pop with color. It’s flower party time as neighborhood yards become festooned with pink, white, lavender and red. So while the rhododendrons sing their song of colors now is the time to pay attention to their needs.
FEED: Early spring through early summer is the time to feed rhododendrons and azaleas. There are many brands of acid-type ferns available. Also, if leaves are pale green, or pale green with dark green veins, add iron to the mix.
WATER: Healthy rhododendrons form a fibrous, light, wide spreading root mass all around the entire plant. Keeping the root area evenly moist throughout summer months is crucial if plants are to bloom and look their best the following year. Drip irrigation soaker rings around the roots work well.
WEED: Rhododendrons do not grow well if their roots are covered with weeds or grass. Keep them weed free at least to the drip line.
MULCH: Mini-fir bark, redwood shred and pine needles all make fine mulch for rhododendrons. Two inches is about enough. Prior to mulching, top dress the root area with a fine acid planter mix. Then add your mulch of choice. It is a good idea to keep the mulch fluffed up so the roots can breathe. Although compacted mulches smother weeds, they also smother rhododendron roots.
PRUNE: Prune after bloom is the mantra when it comes to keeping rhododendrons trim. It is especially important to nip off spent flowers as soon as they fade. When deadheading rhododendrons, take care not to damage growth buds just below the flower truss. With some varieties the buds will be swollen and green. Others may start opening while the truss is waning. Look before you nip.
REPLACE: Perhaps your neglected rhododendron is too far gone to save, or you are impatient to spend the time to rehabilitate. It’s OK to remove the poor thing and send it to the compost pile. Then get to the nursery and find a new one. Now is the time to buy. Flower buds are cracking with color.
Terry Kramer is the retired site manager for the Humboldt Botanical Garden and a trained horticulturist and journalist. She has been writing a garden column for the Times-Standard since 1982. She currently runs a gardening consulting business. Contact her at 707-834-2661 or terrykramer90@gmail.com.
