I don't grow acidanthera, but my bulb book says their culture is the same as glads. If you have had several frosts and/or freezes, I'd say you're safe to cut it back. Otherwise, I'd let it die naturally.

Yes cutting them now will be fine. Al

Thanks to both !!

Now -- this is REALLY, REALLY gonna sound dumb. And please don't laugh at this question :o)

But is a frost/freeze in garden terms the same as weather terms? I mean, if I wake up and there's frost on my car window is that a 'frost' and when the birdbath freezes, is that a 'freeze'??

I'm asking because I know my green foliage has not wilted as it does with what I know to be a "REAL" frost, nor is my ground anywhere near frozen. Remember, I'm in zone 7a on the near the beach in Virginia.

And with all that in mind, if I have not actually had frost/freeze is it STILL okay to cut them off?

Not trying to 'beat a deat horse' -- just want to understand and do right thing.

Thanks again guys !!!

Here in zone 9 the ground never freezes but tender plants do. I have seen years when we had no temperatures below freezing as of the middle of December, but that is rare, and the glads have had plenty of time to re-energize their storage unit or bulb, and removing the green foliage that produces the energy does no harm. On the other hand it does allow you to clean up the garden, at least in time for Christmas. Al

It's not a silly or dumb question at all and I agree the issues can be confusing :-) There are some commonly accepted definitions of what these climate phenomena are:

Frost - when the air temperature near the soil surface drops to freezing or slightly below (32-29F). This will result in the killing of tender plants/annuals but with little other vegetative damage.

Hard frost - temperatures from 25-28F. Widely destructive effect on most vegetation, with heavy damage to flower/fruit buds and tender and semihardy plants.

Hard or killing freeze - temperature 24F or below. Ground may freeze if subjected to these temperatures for any extended period.

It normally takes several frosts before one notices a lot of foliage damage or dieback. If you've experienced enough frost to scrape your windshield or the water in the birdbath freezes, then you can safely cut back the acidanthera foliage. It has been structurally damaged by the cold sufficiently so that it no longer is providing a nutritional source for the bulbs.

Soils in zone 7 seldom freeze to any significant extent. In my area we just experienced an extended cold spell (Arctic front) with temperatures dropping down into the teens at night and not rising above freezing during the day. This lasted about a week. The soils froze for several inches during this period but now that we are back to 'normal' December temperatures, the soils are no longer frozen and quite workable.

That all makes perfect sense, guys!! And thanks gardengal for the weather lesson. That clears things up for me.

Well, I guess last night's weather sort of solved the problem. WE HAD SNOW!! Being almost on the beach, we go years without it, so it's a big deal, even tho it wasn't much and is already melting. It was fun taking a drive in it, but by the time I home, then looked back outside it had stopped. Guess that was 'our' white Xmas :)

As gardengal mentioned it is not only the lowest temperature but how long it stays there. Last year we had a mild winter with the low never getting below 26 degrees, yet we had more damage than normal. Several times the length of time below freezing extended for many hours longer than normal. This year the temperature dropped into the hard freeze zone with no gradual cooling at all and did a lot of damage to plants that survived last year OK. Last year the coldest nights were well into January. Al

Al, I can see that to be the case since after our quick "snow" -- even tho it stayed on some plants for a day or so, most perennials (in pots, waiting to be planted, even) look just as happy & healthy as can be. So I see your point, definitely.......and thanks.
Bonnie