how to grow himalayan birches
The trick to growing birch trees is to know EVERYTHING about them, including the things they like, the things they don't, their pathogens, and their general care. It's not the kind of tree that you can plant and forget, so if you are looking for a low maintenance tree, choose another, but if you are looking for a spectacular tree twelve months a year and are willing to do a few things every year to them, then read this to find out how to make birches happy. Happy trees look better than unhappy trees, and can fend off pathogens better.
Himalayan birch trees are capable of putting out new growth from may to October, and it should be your goal to provide to the tree the food, soil, mulch, and water that makes up the tree's requirements that make the 3-4-5' of new growth possible. Choose a spot in the yard that has great soil and water. Our birches are planted in incredibly awesome soil with an irrigation trench running along the entire length of the planting. The hardwood mulch that we put on every year rots into compost so the physical nature of the soil they are planted in is rejuvenated yearly.
The two signs of a continually growing vigorous birch tree are peeling bark and unfurling leaves. In the spring, you need to see the tips of the branches putting out not only a set of leaves but a set of leaves with a tiny shrimp-shaped tip pushing out leaf after leaf after leaf. The leaves should be a little hairy with a little splash of maroon, without holes or spots. The other sign of a vigorous birch is almost continually peeling bark. When we get fat, we go to the mall and buy new clothes that fit. When birches get fat, their outer layer of skin is pushed off the surface exposing a cinnamon-white inner new skin unmolested by air pollution and lichen and mold. All of these things lessen the whiteness of the tree and are indications of weakness- huge red flags. Trees that do not peel are not happy trees. Unhappy birches attract pathogens by producing ethylene gas that pathogens can smell from afar like a shark smells a drop of blood from a mile away. Make your birches invisible to pathogens by keeping them happy twelve months a year.
This picture above shows one of our 40 year old birches in front of the nursery with a sheet of bark being pushed off, indicating that the cells inside are expanding, a great sign for such a large tree. You can also see the air pollution right there in front of your eyes (we breathe this stuff???). When the peeling is pretty much complete, it's like having a new tree.
Young trees at the nursery showing vigor and turning from the juvenile tan bark to the pure white himalayan birches are known for. The oval raised marks are pustules that aid in allowing the inner tissue to breathe. The conversion to white happens on all plant parts just below 1" in diameter. This peeling occurs more in the winter than at any other time of the year, with sheets large enough to write letters on.
Birch bark is extremely flammable for some reason. If you light a sheet of birch bark, it will burn readily and produce black smoke like a pile of burning tires. The Neanderthals discovered that if they processed birch bark pitch in a certain (still not understood) way, they could "glue" spear tips to the spear shaft and wrap it with leather strips to create an incredibly strong adhesive that scientists unearthed~ 45,000 years later.
Label recently put on being squeezed off by a really happy trunk of a young tree.
The first pathogen I became aware of is the birch leaf miner that chews the chlorophyll and leaves the outer skin on the leaf. It poops little black spots that you can easily see through the tan translucent remnants of the leaves. The outer margin of the leaves stays intact, and the damage to the tree is solely visible, with no possibility of killing nor weakening it. Dry hot summers favor reproduction of this insect, and that's when damage will be unsightly and more visible. There is a very easy fix, however!
Orthene or "acephate" is a systemic chemical that goes inside the leaves to kill anything that is eating them and lasts for weeks and is not washed off by rain. Since you now know that the leafminers will eat the birches, you should spray all the foliage a week after leaf emergence, two weeks later, and again two weeks later. This inoculation will be a good start for the year, with subsequent applications applied when/if you see ANY holes, notches, or leafminer tanning. It's wise to pay careful attention to your tree's leaves like a botanist to keep pathogen populations observed.
Ok, now you know how to identify the birch leaf miner population. The above sketch I drew is the big one to know about. This sketch shows the damage to the leaf caused by the bronze birch borer. The leaf remains deep green in color, but medium to large rounded chunks of leaves around the edges are removed and are easily visible up in the canopy against the blue sky. The adult beetles find the tree either by accident or by the ethylene trail caused by a tree under stress of some sort. AS SOON AS YOU SEE THIS damage, spray the foliage with Acephate.
This chemical is what you need to hire an arborist to apply for you AS A SOIL DRENCH, not to be injected into the trunk under any circumstances. Drilling through the trunk wounds the tree. When a tree is wounded, it produces ethylene gas that flags down nearby pathogens evolved to smell birches. The pathogen heads over to the birch and lays eggs on the bark. Don't let the tree guy talk you into injection.
You can't buy this chemical- it was FINALLY taken off the market by the State of Connecticut but not before box stores and everyone else selling chemicals sold millions of tons of it, eradicating a trillion trillion innocent insects nationwide. as the insects go, so do the birds. I stopped selling this chemical twenty five years ago to all but those wishing to treat just hemlocks and birches, both wind pollinated trees. When watered into the soil two months before bronze birch borer egg laying season, the chemical is taken up with water and translocated to every tree part. When the borer egg penetrates the bark to feed on the cambium, it is instantly killed. You have to plan ahead with birches, and if you do, you will admire yours for decades and decades, just like I have come to love mine.
When uplighting them, use 5000 kelvin 5 watt LED bulbs in low-voltage fixtures. The amount is five times the brightness of halogen with 85% reduction in energy use. I use three bulbs per tree for a total of 15 watts instead of 100 watt halogen we used to use. You can do it yourself!