Boxwood Winter Care

[jasonpg]

I have a couple boxwoods here in Michigan (5b).

One is a small Kingsville. It spent last summer in a southern facing window indoors. It did fine.

The other is a larger unknown type. This is my first winter with this guy.

In this environment, what is the best practice for overwintering?

My options are:

1. Leave them outside against a wall that protects against wind.
2. Put them in a shed
3. Bring them inside

Any advice? Thanks!

 

[JudyB]

I am also zone 5, and have a small kingsville. I take it outside in summer and inside to a sunny location next to a south window in winter. No special setup other than a regular fluorescent light above, and a seedling heat mat to keep it cozy. Probably don’t need the heat mat, but windows can transfer cold. The other boxwood you have will probably want dormancy. How do you overwinter your other trees? I would probably suggest the shed if it doesn’t get too cold or too warm and you can protect from varmints.

 

[jasonpg]

I have a retaining wall that I put everything else against. It protects the trees from the cold westward winds.

I haven’t packed the pots in mulch, but think I’ll start this year to provide additional protection to the roots.

Here is a photo of them (Kingsville on the right), in case anyone has a guess to what the larger one is.

 

[JudyB]

Nice tight little trees, looks like perhaps Japanese box, although there are many types of these. Be careful if you’d u mulch as critters can make their winter burrowsinside this and feed on your nice tree bark. I would do hardware cloth cage system around this area to be safe from rodents.

 

[jasonpg]

Do you have more info about a cloth system? I’m not familiar.

 

[JudyB]

Hardware cloth isn’t actually “cloth”, it’s a metal mesh with small enough openings to keep even small rodents out. Place on the bottom of your area and enclose the sides with a cage type arrangement. I would do a lid of the same that can be opened for maintainance if I kept trees outside in winter. Rodents get hungry,and you’re setting the up with a nice warm nest and a food supply.

 

[Leo in N E Illinois]

Buxus sempervirens - European boxwood is very winter hardy, I have one that I leave outside, under the bench on the ground every winter, in zone 5b. Never lost a leaf or branch through -17 F (about -23 C ). I suspect it is hardy through -25 F, (or -32 C ).

The other species in the genus Buxus are less winter hardy. I have no experience with them. I believe the 'Kingsville' boxwood is Buxus microphylla, the Japanese boxwood. It is native to Japan, which is tricky in guessing absolute hardiness. Japan is subtropical at low elevations in the south, and about as frigid as Chicago at higher elevations in the far northerly islands. I can not tell you how cold you can let 'Kingsville' get before you have problems. I do know majority of people treat 'Kingsville' as a subtropical.

 

[jimib]

I'm glad I read this. I'm in zone 6 and picked up a small Kingsville this year. I do have an unheated greenhouse I could keep it in. It keeps the wind out but still can get quite cold. I also have a south facing window that gets sun all day long I can put it on inside of the house. That room gets pretty warm. Looks like I might just have to bring it in this winter.

 

[Steve C]

I'm in SE Michigan and have a boxwood. I usually overwinter mine with my other hardy trees out in the shed. I know some people here in Mi keep them outside somewhat unprotected, but I figure better safe than sorry. So I usually put it in the shed and cover the pot with some mulch like the rest of my trees that need a dormant period. Been doing that for the past 3 years and it seems to work well for me.