How to care for a large redwood?

Question

I just bought a home in the CA bay area. My front yard is dominated by a large redwood tree that seems in good health. I really love the way it looks. By large I mean 5-6 stories in height, planted most likely in the late 40s. The tree is somewhat close to my front porch in that eventually some of the branches will probably grow out to touch the roof. I assume I'll need to have those trimmed back.

I don't know how much tree trimmers know about redwoods specifically, so I want to be knowledgeable myself. A trimmer recently recommended thinning out the branches and getting rid of the lower hanging branches. I kind of like the lower branches (still above my head) as it feels more forest'y. I worry about thinning reducing the shade.

What kinds of trimming should I be doing regularly other than keeping branches away from my roof? Are there any other things I need to worry about with an old redwood: watering, pests or anything else?

Answer 1

I have never pruned a redwood but their cultural needs are easy to list:

• rich acid moist soil
• shaded and cool roots

Unfortunately this is not a common environment in urban areas. Redwoods that are under stress can come under attack from several fungal pathogens. You can take these steps to keep the tree healthy:

• enhance soil moisture by top dressing with rich compost twice a year, spring and fall, from a foot from the base of the trunk to the drip line to a depth of one quarter to a half inch.
• if possible consider increasing the moisture by sloping adjacent ground so that rainwater goes towards the tree. Do not change the grade around the tree.
• do not prune the lower branches as they shade the roots unless they are dead or crossing each other
• redwoods are surface rooted with most roots within twelve inches of the surface. Compaction of the soil from foot or vehicle traffic "can be devastating". Minimize traffic near the tree. If grass or other plants are growing under the tree remove them and replace with a mulch (redwood bark is good, but ironic).

To summarize from this publication

Redwoods in the landscape appear to do best when their lower laterals are left intact, the lower branches and trunk are shaded and their root zones are mulched. When given these cultural advantages the trees can thrive even in hot inland valleys.

Finally, there is another matter to consider. Redwoods live hundreds of years and get very tall. Local weather conditions across North America are best described as changeable. To have such a tall tree growing that close to your house when there is a chance of high winds could be trouble. What could the consequences be if the tree fell on your house? You may wish to check with your house insurance if you are covered for this possibility and it definitely makes sense to ensure the health of your redwood.

Answer 2

We have a redwood in our backyard; we also live in the Bay Area (San Mateo). Ours is probably about 100 ft (8 stories) high, which is still not particularly big for a redwood. I am not a gardening expert, but here are a few things I do know:

• depending upon where you live in the Bay Area, redwoods do quite well, and are actually planted quite commonly even nowadays in the suburbs even by the cities themselves, where I suspect they know a good deal about proper indigenous plants these days. (E.g., no cities in the Bay Area plant Eucalyptus anymore.)
• at the size that you mention, while the tree is still small for redwood standards, it's large enough that you can assume it merely needs continuing good conditions. So it should be easy to maintain.
• you've already highlighted maintenance you will need to do for considerations beyond the health of the tree (cutting back branches hitting the tree, etc.). So I'll focus only on those for the tree itself:
  • redwoods typically have a lot of foliage underneath them, but little competition: they prefer / need acidic conditions, as mentioned. Few other plants do, and the redwoods like having their "space" (roots tend to be low-ish and wide, not super-deep). So underneath your redwood little will grow well, but that's good for it. Just let leaves & other "junk" stay there so that it provides mulch for the tree.
  • also, you may want to / need to trim back all of the tiny redwoods that will grow nearby it. My tree is in the back corner, so it does not get much foot traffic, but at times it becomes a dense thicket of tiny redwood tree shoots if I don't trim it back. This is how they grow: redwoods tend to grow in small clumps. But I suspect you don't want more than 1 tree in your yard. :)
• Kevin mentions insurance & what could happen if the tree falls. I have also wondered about that: in our case, it is more likely to land on a neighbor than on our house, which I'm especially worried about (can I even get insurance for a neighbor?). But then I realize that the tree will likely live far longer than I will, and certainly longer than I'll live in the house. That's not a great answer, but in the lifespan of a decently well-maintained redwood, we are but a glimpse. Not sure the right answer, on this front.

Answer 3

As redwoods get taller and water pressure within the upper vascular tissue is reduced, the tree responds by decreasing leaf area and dropping higher interior growth. The effect is particularly noticeable on urban or unshaded trees that will lose the desired rounded-point profile and often appear spindly. Proper maintenance calls for removal of the outermost cluster on stressed branches, which will reduce water use, correct profile shape and slow tree growth.