I have 18 of these on my 1 acre property and I would like to try and figure out how old they are. I bought the house almost 2 years ago. Can I measure around the base to get a rough idea? The previous owner put black plastic around a bunch of them so we have been tearing it out. Is there anything we should do to help them as they were very root bound but appear to be healthy. The plastic was done at least 10 years ago as far as we can tell.
Not really, unless you get a coring tool and take a sample core from one of them to count the growth rings. Sequoiadendron doesn't have annual whorls of branches like a pine, so that won't help. A girth measurement will only give a very rough estimate; growth in girth for Sequoiadendron can vary between 5cm to 15cm per year (when measured at 1.5m above ground level).
Hard to their age tell from that skewed pic.. They look to be 15 to 20 years if I had to guess. Upward growth and bole volume can vary depending on climate, soils and access to water.
