Thursday, February 20, 2014

Help Wanted: How and When to Cut Back?

My Dad likes to say, "Dates on the calendar are closer than they appear."

Spring will be here before you know it. This past week, we finally got our first real stretch of above average temperatures with highs in the 60s. I know it won't be long before lots of plants start putting on new growth.

Before that happens, I'm aware that I probably should do some trimming. But I confess that I'm not confident I know exactly how or when to trim. Thus I humbly solicit the expertise of other more experienced gardeners on the following plants. Your advice is greatly appreciated!

Muhlenbergia capillaris, Pink Muhly Grass, Sweetgrass - Some online sources suggest cutting Pink Mulhy grass to 6-inches tall in the early spring. Other sources say that Pink Muhly should never be cut shorter than 12-inches tall, or should be cut back by one-third or even left untrimmed with the old foliage just raked out if desired. You can see why I could use some guidance here from gardeners who have grown this plant.

Schizachyrium scoparium, Little Bluestem, "The Blues" - I was dubious when a landscaper suggested these plants, but I'm oh-so-glad I agreed. This tiny little 'meadow' of waving grasses has been one of the happiest sites in my garden year-round since it was installed. Color me impressed with these golden blues. My landscaper may cut the Little Bluestem for me, but I'd still like to know what y'all think. I think I've heard that Little Bluestem should be cut to around 8-inches tall in late winter or early spring. Does that sound right to you? Or should I just rake/pull out any loose leaves?

Epimedium x perralchicum "Frohnleiten" -- An evergreen perennial with groundcover habit, I've read in the AHS Encyclopedia of Garden Plants that it's often a good idea to clip back old epimedium foliage in late winter or early spring to stimulate flowering and the growth of new foliage. Does this align with your experience? And how do epimediums typically deal with transplantation of I wanted to try moving it someplace a little shadier? (It gets lots of shade in the winter where it is now, but it has to cope with the strong afternoon sun in summertime.)

Dryopteris x australis, Dixie Wood Fern - This is a native Southeast fern that did great last year. As you can see, in winter the stems all collapsed, but the fronds stayed green. I don't have much experience with ferns, but I guess I'm just wondering whether I should cut the fronds at the base where they've already fallen to make way for new fronds in the springtime, or whether I should just let them naturally decompose as they seemed to do regularly during the warmer months last year. (I'm predisposed to just let them be.) But if I were to trim away the old fronds, should I do so now or wait until a bit later in the spring? (I'm not sure when the new fronds typically emerge...)

Finally, there's the question of Aucuba japonica or Gold Dust Plant. I'm probably zone-pushing a little with this plant, but MSU does call it hardy to -5 Fahrenheit. In a sheltered spot, it seems to have come through the harsh winter of 2013-14 (official low temperature of -2) without too much damage. Some leaves have blackened, however. Should I trim those off or will they just fall away naturally and decompose?

I'm most worried about the top part of the plant. Aucuba leaves tend to droop in cold weather and then perk up again when temperatures warm. But the leaves at the top of this Aucuba are staying droopy. And I don't see any new leaves emerging here as they are elsewhere on the plant. Should I trim off this top section or will that permanently stunt the Aucuba's growth?

Just another pic to show the new leaves emerging elsewhere on the Aucuba that I don't see at the top of the plant. From what I understand, Aucubas typically respond well to pruning. Pennsylvania garden writer George Weigel says that the tips of cold-damaged stems can be snipped off in late March just before new growth begins. Does that jibe with your experience?

Thanks for any advice or suggestions you may have. It's always nice when we gardeners can benefit from one another's experiences!