Early shooting of Phyllostachys arcana seedlings

Cold winter is ending

Does the culm finally seem orange? There are also other tiny culms of various ages. The orange one is now 2 years old

Does the culm finally seem orange? There are also other tiny culms of various ages. The orange one is now 2 years old

Winter is not quite over, with morning low temperatures down at -5°C and I saw the first shoots on all of my Phyllostachys arcana ‘Luteosulcata’ seedlings. I planted them into a raised bed and covered with a transparent PVC cover so I could protect it from freezing temperatures during the winter. When the temperature dropped too much, I piled up snow on top to insulate the bed as much as possible. It now seems it worked perfectly. During the winter, the soil got frozen on several occasions, but it didn’t seem to bother the seedlings much. They were showing first signs of dehydration, yet none of them shows any signs of frost related damage. In fact, they look way better than they did when I was overwintering them inside. They struggled each and every winter, except their first year as tiny seedlings.

First shoots in mid March

A couple of small shoots around the clump of older growth

A couple of small shoots around the clump of older growth

None of the bamboos started shooting this year yet, not even the fastest shooter I have, Fargesia Rufa. I was pleasantly surprised to see the first shoots on arcana seedlings, even though they were protected. The shoots are small and there’s no way to tell what kind of upsize is to be expected, but they are here! It could be, that they started during the fall and had now decided to continue with their growth. I doubt it, because all the autumn shoots were whip shoots and these are regular spring shoots (still juvenile). I guess we’ll have to wait and see.

Pink shoot right after it emerged. Quite large compared to other shoots and last year's growth.

Pink shoot right after it emerged. Quite large compared to other shoots and last year’s growth.

Hoping to see an upsize

Small shoot a bit away from the seedling. It had sent quite a few runners last year.

Small shoot a bit away from the seedling. It had sent quite a few runners last year.

So far, none of the Phyllostachys arcana ‘Luteosulcata’ seedlings had shown their parent’s striped culms. I have two vigorous unvariegated seedlings that are going to become at least pencil size thick this year. I’m sure if there is any culm variegation, they should start showing it by now. There are also 3 variegated seedlings that will be interesting to see developing. They are showing quite a lot of differences, even at their current juvenile phase. I’m very interested to see their culms color. It now seems that one of them is going to have yellow-ish culms with an orange tan. I have yet to see if the orange colour persists with age, or is it just a sunburn pigmentation that will eventually fade out.

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A word about first overwintering of variegated seedlings

I still can't snap a photo which shows the true orange color of the culm

I still can’t snap a photo which shows the true orange color of the culm

Winter is finally coming to an end. Days are getting longer, snow has almost melted and mild spring-like temperatures are on our way. This winter was quite cold with temperatures down to -16°C and strong north-eastern wind that emphasized the windchill index. Luckily, we’ve also had quite a large amount of snow during the cold weather. It was not hard to protect bamboos using snow this year, so I expect minimal damage on my larger bamboos, moderate damage on my Moso seedling and no damage on my Phyllostachys arcana seedlings.
I can only hope we don’t get hit by severe freeze in late spring like we did the last few years. It did not affect the bamboo much, so I’m more worried about other plants and fruits around the garden.

Interesting variegation on one of the culms

Interesting variegation on one of the culms

I’m keeping my variegated seedlings in a raised bed. To keep the bamboos protected, I covered the whole thing with a PVC tunnel. It did OK throughout the mild first part of winter, but as it got really cold, I’m not sure the seedlings would be able to survive without better protection. Lucky for us, the polar blast brought some snow, so I was able to pile it up around the raised bed. There was enough snow to cover the bed completely. Later, we’ve got quite a lot more snow and tunnel finally collapsed under thick snow cover. When the worst was over, I removed the snow and found the seedlings completely unharmed. They were in better shape than I hoped they would be. I hope to see a decent upsize this spring. Last year, there were hardly any new shoots, all of them seemed to be survival shoots. They managed to grow long rhizomes in all directions, though, so I expect them to upsize… eventually.

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Protecting bamboo during the winter

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

Drought stressed Moso got severely burnt during the cold weather

Drought stressed Moso got severely burnt during the cold weather

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?

Snow covered Borinda fungosa. Late fall shoots are toasted since first frost

Snow covered Borinda fungosa. Late fall shoots are toasted since first frost

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

Raised bed covered with PVC tunnel and snow insulation. PVC tunnel collapsed due to snow cover weight. Plants were completely unharmed.

Raised bed covered with PVC tunnel and snow insulation. PVC tunnel collapsed due to snow cover weight. Plants were completely unharmed.

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.

Thick layer of snow effectively protects the plants below

Thick layer of snow effectively protects the plants below

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.

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Variegated Phyllostachys arcana Seedlings – Fall 2017 Update

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.

The second variegated seedling getting greener

The second variegated seedling is now the largest

 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.

The first seedling remains the most variegated seedling I had ever grown

The first seedling remains the most variegated seedling I had ever grown

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.

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