Protecting bamboo during the winter
March 10, 2018
Most of temperate bamboos are quite cold hardy, but there are exceptions and every plant’s cold hardiness has its limits. To prevent damage during the cold months of winter, it’s often best to offer your plants at least some protection to prevent loosing your bamboo.
Most common causes of winter damage
Beside the cold itself, sometimes there are other causes of winter damage. In late fall, bamboos go through a preparation period in which their cold hardiness improves considerably. Their growth and transpiration halts to a minimum, some can even shed some of their leaves. When soil is cold, sometimes even frozen, water mobility from roots towards the leaves is extremely difficult process which can even completely stop if the soil or any part of bamboo culm gets completely frozen. At that point, each additional leaf that requires water, means that the plant loses more water than it can replenish. It is also good Idea to mulch the soil around the bamboo with layer of dry leaves, grass or wood shavings. Mulch does attract rodents, which can sometimes cause more damage than the mulch prevents. If you fertilize in late autumn, there is a possibility that bamboo fails to enter the winter preparation and continues to actively grow. During growth it’s much more delicate and can be damaged by either drought, heat or cold. Plants that were already stressed during previous growing season are often more prone to cold damage.
How cold is too cold?
There’s no answer to that one. Cold damages plants, but it usually doesn’t “work” alone. If it’s cold and the weather is overcast or if there’s fog and no wind, there will be much less damage, compared to clear sunny windy and frigid day. Wind can dry out even the most prepared leaves that are coated with thick layer of wax. Sun warms up the dark green foliage that heats up readily, transpiration rate goes up and the roots can’t supply enough water. When you combine all three, cold, sun and wind, the effect is by far the worst. I’ve lost several bamboos in those conditions.
Piled-up snow – best winter protection
When snow falls over bamboo, it will easily bend and soon, snow covers the bamboo completely. That is bamboo’s natural defense against winter extremes and it works extremely well. If there is at least some snow before the cold hits, it’s best you use it! By tarping the bamboo down to the ground, it is easier to cover it with snow. I usually just shovel up a pile of snow over it, and hope enough snow falls before the bitter cold arrives. Tarping bamboo to the ground is necessary when the plant gets larger, but usually gets impossible as the plant matures. Snow covered bamboo makes the air around bamboo leaves warmer than the air above, regulates moisture and prevents desiccation. It is also dark and keeps only minimal transpiration.
All the snow covered bamboos survived the cold blast completely intact. Soil did not freeze under snow insulation and my protected bamboos only suffered minor culm and branch breakage. The much taller and robust bamboo culms that remained exposed got damaged. My Moso seedling that got drought and heat stressed during the summer is going to show substantial winter damage. Tender Phyllostachys aurea is fried up to 50% and Phyllostachys aureosulcata ‘Spectabilis’ (Lamatempel) with no damage whatsoever. All my smaller other bamboos got protected by themselves – snow laid them flat and since the snow cover got thick enough, they remained safe during the severe winter weather with temperatures down to -16°C and powerful dry wind.
Variegated Phyllostachys arcana Seedlings – Fall 2017 Update
October 10, 2017
As the weather cooled down in late summer, all my bamboos started growing faster above and below the soil level. Even the highly variegated seedlings started running with extreme vigor, this fall. The fact, that that they are variegated and have somewhat lower photosynthetic ability didn’t seem to bother them. Most of my Phyllostachys arcana ‘Luteosulcata’ seedlings had shown extreme vigor and tendency to grow many runners that often appear above ground only to dive into the soil again. All the variegated seedlings are showing the same kind of growth, as I’ve already mentioned in previous post.
Leaves started to recover
When the summer heat and drought passed, we’ve been hit by colder than average weather and close to record breaking amounts of rain. We’ve only have a couple of sunny days and most of the time it was raining. All the water managed to wake up the bamboos that were mostly sleeping and quietly storing energy during the summer. Like I mentioned earlier, the leaves were badly burnt in the summer due to high amount of direct sun, heat and lack of precipitation. Days have shortened and the sun lost its scorching strength in late summer. The change made bamboos look completely refreshed and renewed, compared to rather sad burnt seedlings during the summer.
Gradual change of color
I have expected the leaf color to change when the leaves receive different amounts of light and it seems they did turn a bit darker green as soon as sun exposure declined. It could as well be a coincidence related to the growth pattern they are showing – gradual change from almost completely yellow leaves on the bottom of the new shoot, all the way towards the almost solid green leaves on top. Same growth pattern occurs on branches as well. One of the seedlings has wider range of leaf colors, because it gets darker green than the other which remains intensively variegated.
Thickening of leaves
When the weather started cooling down, leaves started changing rapidly. Light and thin leaves thickened and got almost glossy surface. With warm daily high temperatures, all bamboos grew fast, even when temperatures during the night fell below 5°C. It should be interesting to see, how much cold the ‘waxed ‘leaves can hold during the winter. The leaves also started getting a bit darker color on the variegated part of the leaf. Transformation is similar to Hibanobambusa tranquillans ‘Shiroshima’, which turns from cream white to yellow color.
Rhizomes of young Phyllostachys arcana seedlings
September 2, 2017
As I mentioned in one of my previous posts, Phyllostachys arcana seedlings finally started growing rhizomes this summer. Due to hot and dry weather, many of my bamboos suffered from mild drought, but overall, they liked this summer.
The vigorous seedling
Extremely active and aggressive seedling which started running before it was 6 months old didn’t grow much this spring. During the early summer, it only received a couple of new shoots. It’s planted in a bucket, which made it suffer during the dry weather. Occasionally, when I was not around, it got completely dry. When I watered it, it bounced back, but it lost most of the growing tips. It was somewhat pale during most of the summer, so I didn’t expect much. When weather cooled down, I noticed a hole in the pot. Rhizome broke the thick plastic. At that point it was the first time I saw that the whole pot already got deformed, and it was clearly visible that there’s a lot of rhizome activity inside – bucket was bursting!
Until recently, highly variegated seedlings of Phyllostachys arcana ‘Luteosulcata’ were not nearly as aggressive as other, non-variegated seedlings. It seems that most seedlings I started from the Luteosulcata seeds, run with extreme force. I placed the variegated seedlings into raised bed and they loved it. With early autumn, rhizomes also arrived. It is evident, that all the seedlings have rhizomes which love to travel above ground before plunging back into the soil. That makes them really easy to find. Two bright variegated seedlings have very similar leaves and variegation, but they don’t share the rhizome color. The slightly older seedling’s rhizomes are yellow, with only just a notch of green. The other one has dark green rhizomes, similar to the color of regular green seedlings. The same applies to shoot color as well. None of them shows any kind of specific sulcus coloration.
Seedlings that survived the winter outside
I left a couple of weak bamboo seedlings outside, planted in my raised bed. I did not have the will and energy too get them inside and prepare them for the winter. As these were the weakest seedlings, growing in deep shade of my chili plants, I decided I could try their winter hardiness that way. If they would have perished, I would know I need to take care about the remaining plants with more effort. They not only survived the winter untouched, they started running at least as aggressively as my most aggressive seedling at comparable size. Rhizomes are much thicker than those from the overwintered bamboos and they seem to travel even further away. Based on their happiness and vigor, I decided to keep all my variegated seedlings outside this winter as well. Hopefully they will be equally hardy and the winter will not be too hard on them.
The remaining neglected seedlings
I have a dozen or so more seedlings that are inside smaller containers. They were neglected and stayed alive, but remained small – the size of 2 month old seedlings. Their resilience is kind of striking, they were almost completely dried out, frozen, growing in deep shade, bright light and in the end, grass had overgrown their pots. I was thinking about planting them somewhere for a while to help them get going, but I’m really tight on available space. I’ll need to do something about that, but in the meantime, I’ll just try keeping them alive. They don’t die easily though, they are the opposite of Phyllostachys pubescens – Moso bamboo seedlings. Those often die off from no apparent reason just if you look at them the wrong way.
Variegated Bamboo Seedlings – Summer 2017 Update
August 21, 2017
Keeping my 3 variegated Phyllostachys arcana ‘Luteosulcata’ seedlings inside during last winter, caused seedlings to decline. The older seedling that was once larger, hardly managed to survive the winter. At first, they seemed healthy, but they all got some kind of mold infection soon, which didn’t have any visible effect on their vigor, yet they started to decline as they stayed inside for too long. When I planted them outside, their leaves recovered and mold issues stopped, but they refused to start shooting.
A few words about the weather
This year we’ve had a cold spring with severe late freezes. Cold did not harm the variegated seedlings, but the infected moldy leaves fell down. I suspect the much brighter sun fried them completely. New leaves were healthy until later in the summer. Summer brought very warm weather without much precipitation. Temperatures rose up above 38°C a few times and stayed above 30°C almost the whole summer. I planted the seedlings into raised bed, which made them suffer drought a bit more, despite frequent watering.
Heat stress resilience
During first half of the summer, all the seedlings managed to cope direct sun exposure extremely well. I expected the two highly variegated seedlings to have issues with bright light conditions, because I’ve seen last year how their leaves tend to bleach due to sun exposure. Until mid June, there was no damage on any of their leaves. They looked fascinating, despite the fact that they never started shooting and all the leaves and branches were the result of growth that was initiated inside. As summer progressed and sun reached the highest point in the sky, leaves of both bright variegated bamboo seedlings started getting bleached. The strength of the sun was just too much for them to handle. At the same time, we’ve had temperatures above 35°C, which only added some additional stress to the plants. The leaves of all the seedlings curled during the heat and watering didn’t help much. They were not able to supply enough water to replenish the water lost due to transpiration. Over all, heat and sun related resilience was good. I am impressed.
In mid summer when the heat was hardly bearable, drought kicked in. Constant wind and very high temperatures started to show first signs of damage on the leaves. Daily watering was not enough to keep the soil wet, but even when the soil dried out, bamboo seedlings got enough water from deeper roots. When the seedlings mature, I expect them to fare drought even more. In the end of the summer, leaf tips stopped drying. At the same time I noticed they were not sitting idle during the summer. They were producing, a lot!
The dark green variegated seedling
The darker green variegated seedling that was the largest and nicely variegated while I kept it inside, had lost the variegation almost completely. It looks like bright light position makes it greener and shady indoors conditions under grow light caused it to become variegated. I may try moving it into a shaded position or I’ll just divide it and plant it into different locations. It is the only seedling that did not start shooting until late August. There’s one more thing I need to mention about this Phyllostachys arcana seedling – it did not grow any taller. Now it looks like some kind of ground cover bamboo with many tiny culms that only reach 20 cm or so. It all happened when I watered it with an Aspirin solution as I experimented with salicylic acid to combat mold infection. Possible cause could also be the lack of dormancy. I’m quite certain it will start growing next year.
As the summer fell into second half in early August, I have noticed that two highly variegated seedlings started running. Runners started crawling in all directions, often getting to the surface and plunging back into soil again. The seedlings are still small and the rhizomes are also tiny, but the fact that they started spreading with such vigor is very promising. It will be interesting to see them start shooting the next spring when they hopefully start upsizing exponentially.
Winter is coming… eventually
When the warm part of the year ends, I plan to keep them outside in my raised beds. I will cover them with PVC tunnel and hopefully they will like it as much as a couple of tiny all-green seedlings last year did. They are now spreading vigorously, producing quite thick runners. I’ll somehow get rid of those in the spring, to make room for the variegated seedlings. I expect them all to recover even further after they get through their first dormancy.