Hello all, I was hoping to get some advice on growing a potted oak tree, named Oak. He was planted from an acorn this summer and has since grown into a fine young sapling about 12 inches tall. Oak has been living indoors in a 6 inch diameter terracotta pot in the window of a 14th floor condo where he receives full sun. Several questions: When and how should Oak be re-potted? What should I do for winter? Am I going to upset his natural cycle by keeping him indoors? He is starting to get some fine holes in some leaves. A tea rose lived beside him and had spider mites (Rose has since been washed thoroughly and banished to the balcony) I have not noticed the mites on Oak. How long can Oak say potted? Any general advice would be greatly appreciated as well! Photos attached! Thanks, Matt
Hardy plants need a quiet period of some duration, typically at ~35°F. I have a few hardy Oaks but the only one I keep as a greenhouse plant is Laurel Oak from acorns collected in Naples, FL. I'm sure it would die outdoors here, but it's not good looking indoors during winter, anyway. I don't know anyone who keeps our hardy English Oak indoors, but they live as far south as southern Georgia so they can survive winters that aren't really cold (by my standards). I would tell you this: Boxwood, lots of Ulmus, Azalea and a few others will live in the house, but by the end of winter they look pretty ragged and have lost most of their leaves by March anyway defeating the purpose of having them as houseplants. Also, they do not spring back in spring as vigorously as a plant that has spent winter outdoors. Getting ready to spend winter outdoors is a process of completing seasonal growth and slowly being acclimated to lower light levels, shorter photoperiod, cooler temperatures, and drier conditions, all of which contribute to the onset of dormancy. Dormancy of some length is broken in spring not by weather or sunshine, but by the completion of X number of days in dormancy. You have passed Go and collected $200 and are somewhere beyond the graceful beginning of that process which started ~sometime in August. If you put the tree out now, it would have to do in days what normally takes months, so that wouldn't be a good option, IMHO. I have over-wintered a variety of hardy and tropical trees in my basement, away from windows in a cool corner. Water the crown lightly every 2 to 4 weeks such that it is never soggy, but never bone dry, either. When the buds begin to swell bring it to good light, etc. My English Oaks leaf out very late, like late May, so don't be too surprised if they look dead for a long time past what you call spring. There should be an amount of root growth corresponding to the amount of top growth, so don't re-pot until you imagine that the tree is getting close to using up all the space available. You can look at the outside of the rootball almost any time just by knocking it out of the pot, upsidedown. Just put it back if it doesn't have too many encircling roots. Oaks resent the disturbing of their roots in re-potting, so expect pouting for some time afterwards. Do it in spring when buds begin to swell, but be aware of the warnings in the Link below. Some Oaks have a symbiotic relationship with a mycorrhiza, so save some of the old soil when you repot and mix it into the new soil. Disturbing the roots as or when a tree is going into dormancy is asking that the tree doesn't wake up next year. Here in Michigan we are blessed with Oak Wilt Disease which is a big deal. If you have it there, beware.
