Cold hardiness rating for Bambusa Oldhamii?

[Despotate of bamboo]

Although it may be summer time in the Northern Hemisphere, I have found that many sources seem to dispute the cold hardiness of many species of bamboo (including B. Oldhamii).

The most common claims seem to be either 15 Fahrenheit or about 20 Fahrenheit.

Which seems to be more accurate based on your (to anyone who is grown this species or has information about it) experience?

I plan to place protection around my B. Oldhamii this winter. Once I determine whether or not it is going to send up any large culms I will attempt to start constructing something to help against cold winds.

This picture shows the newest culm. It has begun some branching since this picture was taken.
http://photobucket.com/albums/b227/Guildus/th_000_0240.jpg

[Mark Meckes]

Hi, We have a Bambusa oldhamii, Central Texas, which appears a little hardier then our Bambusa beecheyana (both 4-5 yrs in ground). Both are listed in the ABS Source List as hardy to 21F / -6C.

B. oldhamii - somewhere in the upper teens
B. beecheyana - around 20F

Another thing I've noticed is that if a Bambusa culm survive the first winter, it becomes a little hardier for the next winter.

The last two winters have been pretty mild here, not going below high teens F.
As a result our B oldhamii is going to town!

http://www.bamboocraft.net/bamboo/data/505/thumbs/B-oldhamii-ATX050425-175.jpg Bambusa oldhamii (http://www.bamboocraft.net/bamboo/showphoto.php?photo=1006 ) - winter branch tip die-back.

Mark

[Despotate of bamboo]

Hopefully the Bambusa Oldhamii that I have will send up some fairly large size shoots this year and become more cold tolerant. A portion of one original culm did surivive. There are actually two new branches coming off of it however it would be perhaps impossible to see in the picture. The damage in your pictures are mild looking. I hope that the Oldhamii I planted eventually can reach a hardiness like that.

The upper teens do sound accurate for Oldhamii. Some websites say 15 however this seems slightly optimistic, at least for the growing conditions it is in here, since there is another bamboo which is said to be tolerant to 15 (often from the same sources that list Oldhamii as a minimum of 15) which only took very mild amounts of damage (it was slightly more developed than the Oldhamii when winter set it). Your research has indicated that the lower twenties would be unlike in regions with more mild temperatures (with a good degree of maturity). That is good. Since I live near a border line of zones 8b with 9a it should be somewhat similar to your environment. I was somewhat concerned about how much long term progress the Oldhamii could make if the cold tolerance was too much near the worst case scenarios.

[Mark Meckes]

Marginally hardy plants are valuable indicators of annual climate/weather changes. Not knowing how they will perform makes for an interesting gardening experience and challenge.

Some thoughts from another thread of why ...

It's difficult to determine the cold hardiness of a bamboo by a single temperature reference alone.

Here's some other things to consider ...
- growing conditions, location/micro climate, sun/shade, daylight hours,
- age of new culm and hardening of growth prior to cold weather.
- weather quality prior to onset of winter (affects leaf/branch development and food supply for the following year.
- numbers of extreme cold periods during winter season.
- duration and day/night temperature of each extreme cold period.
- extreme temperature drops (warm to frigid)
- amount of wind - wind chill factor
- snow cover
------------------

One thing that happens to our Bambusa oldhamii, even with just partial branch tip dieback as shown in the pic in post #2 ... In May and June by it responds by sending up lots of smaller shoots, up to an inch+ (3cm) or so in diameter. It makes for a very impressive bushy plant.

However this year I have been removing most of them as they appear, hoping to divert all it's energy towards the hopefully bigger shoots which will be hopefully emerging sometime in July.

I'm doing this knowing too well that the later `big ones' may not survive the winter and I'll be starting from scratch, whereas if I left these smaller earlier shoots, at least they would probably survive.

I have a different problem. I planted the oldhamii too close to the house - 10 ft away, and these smaller shoots have very wide-spreading branches blocking out access of the pathway around the house.
I am waiting for a winter with a hard freeze and complete top dieback, then I'll dig it up and move it 20 ft from the house.
Meanwhile I'll try to coax new culms to grow on the `away' side of the clump.

Mark