by Dan Secrist
About 20 years ago I planted thyme in my Japanese Garden: woolly thyme, nutmeg thyme and minus thyme all in distinct areas i.e. separated. It took a few years for them to fill in but when it was done, it was spectacular. I always had to do some weeding, but it was worth it. Cars would stop to admire and ask questions about my "moss!" It was especially dramatic when all in bloom.
Several years ago, the thyme began to die off. I tried everything I could think of to remedy but to no avail. Large bare spots appeared. Sometimes they would fill in the following summer, but then die off in the fall and winter. Other places the once six-inch deep thyme died back to an inch of sickly-looking plants.
I finally discovered large white grubs in the soil. I put grub killer on it and some places really have recovered. I am happy about that, but still, even after 3 years of careful application, I have some areas that are not doing so well. It's much better, but not near what it once was.
Hi Dan, I would love to see some pictures of your project, from your description it sounds lovely.
Thyme is an odd plant, it can die back for almost no reason, which is very odd for a supposedly tough plant. The grub issue is interesting, I'm wondering what those would have been - crane flies, maybe?
If your plants are anywhere that has standing water at any time during the winter especially, this can cause major root problems.
It's also important that they don't have any run off that might contain salt from de-icing, or water that stands and freezes on them. If your area is well drained, this shouldn't be a problem, and it is especially puzzling that they have done so well for a long time, and are showing a decline now.
Of course, it could be that the plants are now so old that they need to be replaced; however, I might try to renovate them first before digging them up. Top dress them with small gravel, which they can root into. Don't dump it on too thickly, allow it to sift down into the crown.
I would use something that would pass through a screen with about one sixteenth inch holes, but it's important to sift out the very fine dust too, which can clog the pores of the soil.
Other than this, I'm at a loss as to what else to suggest, sorry.