I am not sure about the Penstemons as I've had mixed luck with them but DO NOT cut the Caryopteris to a stub or that will be all she wrote. At least that was my experience the first and last time I did that. I now lightly trim the tips back to a viable bud. You could cut it back a bit harder when things really start to pop but I think it is still a bit too early! Good luck and I'm sure someone else will add their two cents worth also.

I second the opinion about the Caryopteris. It's sort of like lavender, in that you do not cut it back to the ground, or that will kill it. Since it's summer blooming, I believe you can prune it in the spring, lightly to shape it. That's what I'm going to be doing to mine since they really took off last summer and are looking untidy now.

Caryopteris is considered a dieback perennial in colder climates than ours and yet successfully returns each season, so cutting back as recommended should not have any ill effect on its performance here. What it does require is rather lean and very well-draining soil in full sun, similar to conditions preferred by lavender. Too much winter wet is generally what affects its ability to thrive, not its cutting back. I would suggest you wait until somewhat later in the season for this procedure (not cutting back usually results in bare, leggy stems with growth centered at the top). I prune mine when I prune or clean up hardy fuchsias - late April or May when danger of frost is past and foliage buds are clearly evident and starting to emerge.

Thanks for your advice!
So, when I cut it later in spring, about how far should I cut? I want to do it right.
And how about the Penstemons?

I've grown Penstemon in Tacoma for several years. They are one of my favorite perennials, and I think should be used more. Almost evergreen here, long bloom time, no pest or disease problems. Fairly drought tolerant in summer.

The first couple of years I didn't cut them back because they were always putting out new growth. But I learned that if you don't cut them back, they will get very top heavy and flop over. Some types have stronger stems then others, but even those may need some staking.

I still don't cut them back too far. Anywere from l/3 to 2/3 of the stem, depending on where the new growth is coming from, and how ratty the top looks. The stems get very woody as they get older, and so I have hesitated to cut them back too hard. (I just nipped back some last week, and yes, they were showing new growth.)

I, too, will be interested to hear what other gardeners are doing with their penstemon.

Daphne in Tacoma

Here is a link that might be useful: web penstemon photos

Daphne, I really appreciate your input! It was very helpful. I just looked at my 'Patio Wine', and it is a bit floppy. I thought I detected some growth at the bottom, but I think I'll wait till I see more new growth coming up. I'll feel better about cutting them back if I see that. I'll go check the 'Firebird' tomorrow.

Any more advice?
I particularly want to know:

HOW FAR do I cut back the Caryopteris?

Far enough to remove any obvious tip dieback and to encourage a full and bushy plant. Hard to be more specific :-)

Brickell/Joyce, Pruning & Training (DK) puts it this way:

WHEN TO PRUNE Mid- to late spring, as the buds are breaking (when dead wood is more obvious), and when severe frosts are no longer expected.

TRAINING AND PRUNING Develop a low framework by pruning young plants hard in the first spring after planting. In subsequent years shorten all stems by at least three-quarters of the growth made the previous year, cutting to within 1 in (2.5cm) of the older wood. Do not cut into the established framework, since plants will very rarely produce new shoots from old wood. To renovate neglected specimens, cut stems back in spring to the lowest active buds that can be seen. Plants are unlikely to survive more drastic pruning.

My Caryopteris have branches that are 3 to 4 feet long.

I will cut them down to about 1 foot long But, not yet. It is too soon.

I always make sure there is new growth on whatever I'm leaving.

Sometimes I go back and cut again if growth does sprout out lower on the stems because my border is crammed full and I wish the smaller Caryopteris were available when I planted mine but they weren't. That I knew of anyway.

I actually cut my 2 caryopteris bushes last Saturday during that gorgeous weather we had. Mine surprisingly already have new leaves emerging, so it was easy to see what to cut off (otherwise I would have waited). The tips of mine were dead, so I just cut back to a pair of buds that were leafing out. Hopefully I didn't do this too early...

What I do with my valued marginally hardy shrubs is wait until they really show signs of new growth then cut them back to the first buds that are obviously showing new growth. I let them really start to develop, then cut the branches back a bit further to promote even more growth below. This has worked well for me on my Crinodendron hookerianums and purple leaf sage and some Pittosporums. It doesn't hurt to wait until you really see signs of new growth!

I prune my Caryopteris back to 5 or so active buds per branch. It looks pruned pretty hard when I am done. Usually I wait until it is a little warmer and more buds are evident. Every year the plant turns into this huge shrub so it doesn't hurt it a bit. If you want more little cary's just push the cut branches into the soil after you prune. At least half of them will root if you keep the soil from drying out completely and start in partial shade. These little guys will be smaller for the first year or two so they might be good for areas where you want a smaller bush that you can remove when they get too big.

If my penstemons start looking woody or freeze I cut them back too. I just make sure to leave a little something to grow out. Sometimes if the growth is fairly nice looking I don't prune them. This year I have green plants (even after the freezing weather) that don't look woody. I think I will leave most of them the way they are. These things will also root like weeds if you want more. Just stick the cuttings in the soil right after pruning. I tend to take out penstemons when the plants get old and these cuttings keep the plantings renewed.

Enjoy,
Amy

Thank you for your additional advice!
I did cut both the Penstemon down to the new growth. They were floppy, and a couple stems on the Firebird were slightly woody. I hope it works out okay.
I haven't done anything to the Caryopteris yet. It does have buds on it, but it's still hard for me to tell where the new growth meets the old growth. ;) I'm going to wait till later in spring.
BTW, mine is a smaller variety, which is why I got it. I didn't have room for a bigger one! Besides, all they had were small varieties at the nursery where I worked.