When the flowers are almost spent and the stalk is drooping, what do you do...cut it off?
Go ahead and deadhead the flowers once they are 3/4 of the way faded. Foxgloves are biennial so if you would like them to re-seed you may leave the flower spikes. Check out the link below for more information;
http://www.gardening.cornell.edu/homegardening/scenec1a6.html
I have a foxglove in a pot on my deck which is in the shade. It gets gentle morning and late afternoon sun. It has bloomed beautifully for several months. I keep the soil moist. Lately I've noticed that the leaves are turning white. There is no fungus or spores or bugs. It's just like the color is draining from the leaves. Any advice? I am unable to upload photos from my phone for some reason.
This could be a nutrition issue. Foxgloves need a balanced fertilizer application once a month.
Crown rot is the most common issue with Foxgloves, but you would see yellowing leaves, not white.
https://www.gardeningknowhow.com/ornamental/shrubs/rose-of-sharon/rose-of-sharon-bush.htm
Can you please tell me what plant/weed this is that has grown in my garden? Regards Jan.
Looks like Grecian Foxglove (according to google image search)
Appearance varies depending upon developmental stage.
Digitalis is extracted from Foxglove - attempting to distill digitalis results in decomposition.
This link may help you with the process.
http://www.henriettes-herb.com/faqs/medi-4-1-distilling.html
What does a new foxglove plant look like? I have a new plant that is about 3 inches tall, and looks kind of like an artichoke. Is it Foxglove? I don't have a photo.
This links below have some images and care information.
If in doubt, leave the plant! Time will generally tell!
https://www.growplants.org/growing/foxglove
https://www.gardeningknowhow.com/ornamental/flowers/foxglove/foxglove-flowers.htm
What size container is needed for one penstemon?
Pot size will depend on the size of perennial plant that you start with. If you purchase a starter pot--example a 4 to 5 inch pot size, you can go ahead and plant the Penstemon in a 8" pot.
You can sometimes locate larger potted Penstemon and you would pot up them about 1 size larger then the existing greenhouse pot.
https://www.gardeningknowhow.com/ornamental/flowers/penstemon/penstemon-beard-tongue.htm
Do foxgloves produce more than one flower stalk a season?
Yes, I have often have had 2 and on occasion a 3rd stalk from some specimens.