Protecting and Growing Bonsai


Posted by Horticulture Guy - Peter Punzi | Posted in Midwest U.S. Gardeners | Posted on 15-04-2006

Q. I would like to create some artificial “Growth zones” for some bonsai trees. I would like to create a zone 7. How would I go about doing this and what kinds of artificial lights would I need? Charley Stran – Eau Claire, WI
A. To create a true zone 7 inside a home can be difficult especially if you are growing deciduous bonsai specimens.  The USDA zones really only concern themselves with the lowest minimum temperatures.  But the zone still has cold temperatures and daylength changes that are necessary in the proper amounts to trigger dormancy and then to break dormancy. You may be able to achieve this in an unheated garage and use a light timer to change the day length to match outdoors resetting it once weekly to follow the seasons. The grow lights could be as simple as fluorescent full spectrum bulbs (or one warm white and one cool white bulb) or as sophisticated as metal halide lamps.  If you are using an unheated garage you may need no additional heat but you should be sure that the temperature doesn’t go below 10 degrees F, which is the upper threshold for zone 7.   Many bonsai enthusiasts have outdoor hotbeds, which are essentially cold frames with heating cables on the bottom.  Most deciduous specimens will need a specific dormancy period where the temperature is between freezing and 45 degrees F.  If you can provide that you can grow most deciduous plants.  Don’t forget plants have a range of zones that they can grow in.  They will have a lower limit zone and an upper limit zone.  The lower limit zone is usually based on the coldest temperature it can tolerate.  The upper zone has to do with how warm the winters are and dormancy.  This is why Florida grows citrus and not peaches or apples.  It is to warm in the winter and the peaches and apples don’t break dormancy. 

Shade Tree Suggestions


Posted by Horticulture Guy - Peter Punzi | Posted in Midwest U.S. Gardeners | Posted on 31-12-2005

Q. I want to plant a nice shade tree in my back yard. It seems like every tree I consider has its pros and cons. I am most concerned about the mess—I have installed a beautiful clay paver stone patio that we use like another room in the house. I love Oaks but I don’t want acorns all over the patio. I love Maples, but I don’t want those helicopter things falling either. A medium-fast grower would be great. I live in Minneapolis. (zone 4b, I think.) Any advice? THANKS! Mark Jacobson – Minneapolis, MN

A. I am inferring from your question (since you mentioned maples and oaks) that you want a deciduous tree that provides shade in the summer and then allows light during the winter.  So I assume that you are all right with leaf raking duty but just not dealing with a trees fruits/seeds.  Since fruit/seed comes from female flowers (or the female part of a complete flower) selecting a species of tree where the trees’ gender is split by individuals would be useful.  This setup in a plant is called dioecious (Greek for two houses).  So one tree has male flowers only and the other has female only.  Oak and Maple (as well as many other well known trees) are monoecious (you guessed it “one house”) so both flowers are present in each individual.  There can be either both male and female flowers on the plant or a complete flower that contains both the male and female parts (like a hermaphrodite). The Ginkgo (Ginkgo biloba) is a dioecious shade tree whose cultivars are asexually propagated (cloned) from male trees.  This has been propagated this way because the female fruit stinks to high heaven!  Another alternative is to find sterile trees that don’t produce fruit or seed like Marshall’s Seedless Green Ash (Fraxinus pennsylvanica) as well as many of the other ash hybrids that are seedless.  Now that you know to ask for male or sterile cultivars of shade trees you can also visit your local nursery to find out what selection is available to you locally.


Tip Browning Mass Cane


Posted by Horticulture Guy - Peter Punzi | Posted in Midwest U.S. Gardeners | Posted on 24-12-2005

Q. I have a plant labeled as “mass cane.” I’ve noticed recently that most of the leaves are starting to turn yellow at the tips and eventually the yellow turns brown. I have not watered the plant for 2-3 weeks now for fear that it has been over watered. I’ve checked the soil and it seems as if at least the top half of the soil depth is mostly dry.  I bought distilled water for the plant because I’ve read that fluoride can cause yellowing in the leaves. So the last time I watered it I used the distilled water but that didn’t seem to help. The plant is in a bed room that has a window (mostly covered by a curtain to block direct sunlight) facing the south so the plant usually receives a decent amount of filtered light. Also about a week ago the plant fell but landed upright; there was no damage to the plant but the canes probably moved around a little  in the soil. What needs to be done to keep this plant healthy? Matthew Broten – Champlin, Minnesota

A.  You mass cane is a common name for Dracaena fragrans ‘Massangeana’ also called a Corn plant because of the shape of its leaves.  The variegated (with the light yellow/green stripe in the center) seem to need more light, perhaps because there is less chlorophyll on each leaf.  When I was working in indoor landscaping it seemed that I would need to trim the necrotic tips off of the plants that received the least amount of light.  Although they are tolerant of low light levels I always found that they did best with some direct light for part of the day. Of course the more light they receive the more water they require making it less likely that they will be overwatered.  Overwatering (as I suspect you know from your question) will suffocate the roots and kill them.  The symptoms are the same as underwatering because the plant itself is not receiving water. If the leaf tip symptoms showed up only after the plant fell it is possible that there was some root damage and this is causing the lack of water.  It is good that you are using non fluoridated/chlorinated water since this means we can eliminate this as a potential cause of the problem.  I would trim the tips and continue to only water the plants when you feel the soil has become moderately dry.