Can’t See the Forest for the Redwood
March 20, 2013
Coast Redwood (sequoia sempervirens) is a forest tree with a native range along the coast of central and northern California. It has been cultivated for use in non-coastal and non-forest landscapes with results that are not always favorable to growth or long term establishment.
A natural redwood environment is abundant in rainfall and fog with an additional benefit of cool, moist air. From the natural shape and proximity of other redwoods, the trunk and roots are shaded. In addition, many years of needle litter cover the forest floor, keeping the shallow roots protected. Here are some conditions that can be created to enhance the health of redwoods in urban landscapes.
Redwoods are adaptable and there are many healthy specimens in hot inland valleys. However, not all varieties do well in hot climates. Check with your nursery for ‘Aptos Blue’ or other varieties that will survive longer away from the fog belt. Cultural practices will make a difference in how they look and grow in urban environments.
Consider the following before placing a Redwood in your landscape:
- Plant in the landscape where the tree will not receive an abundance of south facing heat. For example, trees planted on the north side of a fence will do better than ones with direct sun from the south.
- Avoid heavy pruning. Particularly around the lower portion of the tree. These lower, wide branches prevent sun damage and help the trunk and roots cool.
- Allow the needles to drop on the ground around the tree to maintain moisture, keep the soil cooler and to avoid compaction to the roots. Lawns under trees are not advisable as it is necessary to prune the tree up in order to mow the competing grass.
- Other plants will compete for moisture and nutrients and disturb the shallow roots of redwoods. Keep plants away from the base of the tree.
- Ensure adequate moisture to the roots to avoid disease and increase growth. Spraying water on the canopy will not simulate fog and could increase disease in the summer months.
- While adequate water is important, over watering can kill roots and invite disease. Some water systems are high in salinity and can cause injury to trees. Have water systems tested.
- Avoid compacting soil around redwoods. Clay soils compact easily, roots are smashed and water cannot properly drain. Soil that is compacted and dry will not take in water easily. Soil that is compacted and wet will not easily dry out.
When given these cultural advantages, Redwoods can thrive even in hot inland valleys.