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.