First off, make positve ID on which St. John's Wort you have. If it is indeed Hypericum perforatum (small leaves, hold up to light, look for tiny black spots) it is not to late to tincutre the top 8-10". I have done it once, have enough to do it again this week and once more, then I will cut them back to about 2 foot tall and hope for a late flush of flower again. A few inches tall would probably be too severe of a trimming this time of year.
Hope this covers the questions, and enjoy! Lynn

Thanks Lynn! Mine does have the tiny black spots, and this evening I cut off a bunch of it and am ready to make some tincture.

What all do you use the SJW tincture for?

Fern

Very cool. Glad you have the right variety, as it makes superb medicine!
I use tincture when I'm feeling "blue". A week or two of dosing, and i'm not feelin' so much like Eeyore.
The oil makes an excellent medicine to rub on sore backs. Specifiaclly used for sciatica neve pain, and heck, you ever known a gardener that didn't get a sore back? Also used to treat wounds & burns including sunburn. I include SJW oil in my gardeners hand salve.
Enjoy! Lynn

Here is a link that might be useful: Herbalgram on SJW