A dead tree or shrub? Learn from a post-mortem analysis

Last Updated: 
December 29, 2011

CORVALLIS, Ore. – Often we discover in the spring that a tree or shrub just didn't make it through the winter. There are many reasons for a woody plant to succumb and a "post-mortem" analysis can point out clues.

The weather is the first possible culprit, said Barb Fick, home horticulturist with the Oregon State University Extension Service. A stressful winter, with heavy snow and ice, can break a lot of limbs.

"Rapid temperature fluctuations from warm to cold also can stress a woody perennial enough to kill it, especially if the perennial is not a hardy variety nor well-established," Fick said. She suggests using boughs or pruned Christmas tree branches to protect plants during cold snaps.

Disease or pests can kill a tree or shrub. If you find an ailing plant, take a sample of it before it dies to a horticulture specialist or OSU Master Gardener at your local county office of the OSU Extension Service.

The cause of death might be related to its care. Did you plant it correctly? If you did, you gently loosened matted roots after removing the container. You also used the same soil you took out of the planting hole to backfill and didn't place the plant too high or too low in its planting hole.

Did you fertilize it too much or not enough? If you mixed a handful of chemical fertilizer into the hole when you planted the tree or shrub, it could have fatally burned the roots. Try an organic fertilizer next time. Rotted manure, compost or an organic mix are less likely to burn the roots of a woody perennial. Or you can wait to fertilize until after the plant begins to establish.

Did you plant it where the drainage was poor? A common reason for shrub and tree death is poorly drained soils. The roots become waterlogged and die. To improve drainage, add lots of organic matter such as compost over the entire area. For very poorly drained soil, consider building a raised bed.

Did you water it enough last summer? Newly planted shrubs and trees do not have extensive root systems. Water them often, slowly and deeply at their base. Pay special attention to plants that grow under the eaves of the house. They receive little moisture and can dry out easily, especially in dry years.

If the plant had pale green, undersized foliage and little growth last year and has never been fertilized, it may have just expired for no good reason at all.

Author: Judy Scott
Source: Barb Fick