Is St. John Wort resistant to wild deer?
Yes, St. Johns Wort is deer resistant. Aromatic plants like russian sage and other herbs are also not deer favorites. Nothing is deer proof when food supplies are short. Choose a variety of Hypericum that is not invasive in your area.
This shrub has frozen back to the ground the last 2 winters. Evidently it is not winter hardy at location 40165. Should I cut it back each year?
This plant dies back to the ground in the colder parts of it's range, garden zones 5-9. Since it blooms on new wood, this is OK. This is just like butterfly bush, Buddleia , and bluebeard, Caryopteris. Both die back to the ground in colder climates but comes roaring back in spring. People living in warmer winter areas often cut their Hypericum back to 8 inches or so in early spring. I would leave the shrub intact for the winter as it will trap leaves and give it some additional winter protection. The following article explains what agricultural "zones" are. You can use it to find your zone. https://www.gardeningknowhow.com/...zones/usda-planting-zone-map.htm
I moved it because it was getting dry too fast. It's in a NE window and leaves The leaves turned red. Too much sun? Would a W window work better?
St. John's Wort will handle full sun with no problem. Red foliage is common with a phosphorus deficiency. If you are using miracle grow with slow release nitrogen, then this can be the cause. This tends to lock out phosphorus for awhile to allow for uptake of nitrogen, which in this case is not a good idea.
If you are using a low fertility soil, then this can be a general deficiency. I recommend feeding potassium phosphate, or a bloom formula feed with less, or very little nitrogen than an all purpose.
This article will give you more information on the care of these: https://www.gardeningknowhow.com/edible/herbs/st-johns-wort/st-johns-wort-plant-care.htm
Planted years ago and have never flowered. Help !
A soil test may show excess nitrogen in your soil. Add some bloom boosting phosphorous; such as Bone Meal to the soil.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/bone-meal-fertilizer.htm
https://www.gardeningknowhow.com/edible/herbs/st-johns-wort/tutsan-care-in-the-garden.htm
I want to put St Johns Wort in dried flower arrangements.
Sure. We have a few articles that will help: https://www.gardeningknowhow.com/garden-how-to/projects/drying-flowers-and-foliage.htm
https://www.gardeningknowhow.com/garden-how-to/info/flower-drying-methods.htm
https://www.gardeningknowhow.com/ornamental/flowers/roses/wax-dipped-roses.htm
https://www.gardeningknowhow.com/ornamental/flowers/fgen/flower-food-for-cut-flowers.htm
ly? My seedlings are about 6 inches high now.
Prune it every year in early spring to increase fullness and keep desired shape. Here is how:
https://www.gardeningknowhow.com/edible/herbs/st-johns-wort/pruning-st-johns-wort.htm
https://www.gardeningknowhow.com/edible/herbs/st-johns-wort/st-johns-wort-plant-care.htm
We have a stream bank about 10' x 100' that receives about 4 hrs. of morning sun and the rest of the day is light shade. Beautiful ivy has been on the very steep stream bank for decades. Deer or something else has has removed most of the foliage, leaving only woody stems. Hypericum calycinum seems to be a great alternative as it flowers and is supposed to be deer resistant. My only concern is weed control. I am 71, so constant heavy weeding won't work for me further down the road. Also, will this species tolerate my stepping on it for light weeding, fertilizing, pruning, etc.?
You are in zone 7a, which should be fine for this particular ground cover.
https://www.gardeningknowhow.com/garden-how-to/gardening-by-zone/zone-8/zone-8-ground-cover.htm
Know that the plant can become invasive, which could cause you some problems down the road. I imagine that weed problems will depend upon how close together you plant the ground covering, as well as other factors such as soil, sun, etc. Here's an article that discusses dense planting for weed control - hope this helps:
https://www.gardeningknowhow.com/ornamental/flowers/fgen/planting-flowers-to-deter-weeds.htm