I love your article on when to prune…so timely and I realize that I just made a big mistake about pruning 3 viburnum bushes by 40% yesterday. I did not touch any trees or azaleas. I will wait to prune my cherry tree the dormant winter.
I have a mountain laurel bush that has half of it’s leaves staying brown. It was planted 5 years ago and has not performed too well. Should I just replace it? What do you suggest?
Depending on how you pruned your viburnum, they may still have a few blooms next spring – unless you sheared them. If you just thinned them, there may still be some flower buds left.
As far as your mountain laurel, I wouldn’t give up on it yet. Mountain laurel requires moist, well-drained, acidic soil with plenty of organic matter. Have the pH of your soil tested. The optimum pH for these shrubs is below 6.0, preferably 5.5 or lower. Lower the pH using iron sulfate or aluminum sulfate if necessary. Apply according to the label directions. Fertilize them with Espoma Holly-tone in the fall and spring. I would do this now.
Drought and winter burn can cause the leaves to turn brown and leathery. Unless you have a good soaking rain, be sure to water the shrubs deeply every 10 days or so through the growing season especially during times of drought. Give them a good deep watering in the fall before the ground freezes. Mulching will help keep the soil evenly moist. To help protect them from winter burn, spray them with Bonide Wilt Stop according to the label directions.
These shrubs are also plagued by leaf spots and leaf blights. It is important to rake up any fallen leaves and twigs from under the shrubs in the fall as the fungal spores that cause these diseases will overwinter in this plant debris and can reinfect the shrub in the spring. Spraying with a fungicide like Bonide Copper Fungicide or Fung-onil when the buds begin to break dormancy in the spring will help prevent these fungal diseases.
What I would do for this mountain laurel is to cut it back hard to healthy, green wood in mid-March. These shrubs have dormant buds in the bare wood that will grow and create a fresh, new shrub for you in a few years. Keep it fertilized and watered and check and adjust the soil pH if necessary.