- My Heather plants have died in one area of garden but are fine in other areas. Why might this be?
One of the main considerations for growing healthy heathers is soil type. Most need an acidic (ericaceous) soil with a pH of 6.5 or less although some will tolerate a slightly more neutral soil environment. This is fortunate for us on the west coast as most areas here have naturally acidic soil. They need to be sited in an area with free draining soil rich in organic matter such as well rotted compost, leaf mold or well composted pine bark or needles. If you have healthy Rhododendrons (or Hydrangeas that have blue flowers) in your garden or nearby gardens, that’s a good indicator that the soil in the area is acidic.
There are several factors that will determine whether your heather plants will flourish, merely survive, or fail altogether. Heathers prefer 6-7 hours of sun, with a little shade, at the hottest part of the day. Provide a screen of other plants or a fence to protect them from the wind if they are planted in a wind-prone location. Avoid planting them under eaves of buildings where they will receive little natural rain fall. Avoid planting too deeply. An inch of the root ball should be above the soil line when planting new plants and the area above the soil should be mulched with two inches of pine or shredded bark mulch. Avoid cultivating around the roots. They are fine, shallow, and easily damaged. Heathers can be fertilized sparingly in the late fall after a hard freeze or in the early spring. Most however thrive in infertile soil.
Heathers can be equally stressed by drought or waterlogging. Given the hot dry summers that the west coast has been experiencing over the last few years, drought is a very possible cause of the failure of these plants, particularly if they are in a sunnier or windier location than the plants that survived. An inch of water per week is adequate for the plants in a dry spell and to avoid overwatering or the use of overhead watering systems which can give rise to other fungal infections such as powdery mildew or rust. Once the plants become stressed, they are vulnerable to pests and diseases such as spider mites and scale insects which can weaken and even kill the plants.
‘Root rot’ is the most common cause of root and stem base decay of a wide range of trees and shrubs, including heathers. It is caused by a fungus and inspection of the roots will reveal that many of the smaller roots have simply rotted away. There may be brownish/blackish growths on the tops of the major roots. Above ground, the foliage fails to develop well, then yellows, dies, and drops. Sometimes this happens gradually, other times quite quickly. The entire plant may turn brown and die. Dig up one of the dead or dying plants and inspect the roots for any of these symptoms. If root rot is confirmed, the affected plants should be removed and disposed of (not composted) together with the soil from around the plants. It is advisable not to plant heathers in the same spot for a few seasons.
Heathers and Heaths (Calluna, Erica and Daboecia) are a wonderful addition to a garden. The bell-shaped flowers are much loved by bees and an important food source for them as well as other insects and Hummingbirds. Heathers are generally tough, hardy and, for the most part, trouble free. They are evergreen and a mixed planting of different varieties gives the opportunity for year-round colour in a garden.
Sources:
https://www.rhs.org.uk/plants/2712/calluna-vulgaris/details
https://extension.psu.edu/ericacea-heath-family-and-their-culture
Sustainable Gardening – The Oregon Washington Master Gardener Handbook (2013)
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