Saturday, September 26, 2020

Acer Negundo #1 - Box Elder Maple

Acer Negundo - Box Elder Maple
Age: about 4 Months

September 2018: This small box elder maple started this summer as a small sapling in the front yard growing wild. I initially thought it to be a Red Maple, but after five sets of ever-morphing cotyledon the tree's leaves finally fully formed into the identifiable three-leaf box elder leaves so often mistaken for poison ivy. Unlike poison ivy, box elder maples have opposite leaves while all poison ivy forms have alternating leaves on the stem. Close inspection of the trunk at this point shows small buds where the earlier leaves fell off. I may potentially get some new branching there in the spring. Currently the tree has about six sets of fully formed leaves. I'm not sure with the weather dropping in temperature if the final set that is budding will form. Currently, I've stopped watering the tree, because the soil has remained moist and has not dried out for several weeks. Soil in this pot is basically a mix of organics and small bark chips for drainage. I plan to repot in the spring into a more suitable mixture.

The true leaves have not yet begun to turn autumn colors but I expect that within the next week or two, with the colder temperatures we expect, that the tree will begin to lose it's leaves. My over-wintering plans for this tree is, once it loses it's leaves, to place it in the back shed where it will stay out of the wind and elements. My watering schedule will likely be every other week. I may attempt to slow water it with a block of ice or snow on top of the mulch. I've heard this is a good way to allow the roots to stay slightly wet throughout the winter, while still keeping them cold and in a dormant stage until spring. I am hearing we may have a mild winter, however, and if this is the case, I will likely give a small amount of water every other week.

March 23, 2019 (Age - 11 Months)


After keeping the Acer Negundo through the winter outside mostly, with a stint inside to slowly unfreeze the root ball, I decided to replant it to get it into a better soil that would prevent the plant from being in something as moisture retentive as the potting soil / bark mixture I had it in. I repotted it a week ago.

To keep the tree healthy over the winter, I mostly left it in my shed to protect it from desiccating winds. I occasionally misted or watered the plant when the soil felt dry but because the tree doesn't transpire at all during the winter, I only did this every three or four weeks starting mid November. At one point in January, the root ball had completely frozen. Because Box Elder is such a hardy species, it could withstand the freeze however other trees would potentially die from this. I was concerned that the roots would not handle the constant freeze and refreezing if left in the shed so I moved the small plant into a spare refrigerator inside and I covered the soil with ice. As the ice slowly melted into the soil in the fridge, the tree slowly underwent a thaw cycle. Once thawed, I was able to place it back outside.

The repotting process on this tree was very simple. I raked the root ball out so I could see all the roots. I started with the root ball as in the first image above. Using a small rake or bent fork to look like a rake, I removed the soil. I kept the roots misted to make sure they did not dry out. The root ball had a lot of healthy roots. I pruned the tap-root back slightly to encourage more roots near the base of the tree. I made sure I had some finer feeder roots above the point I cut the tape root to make sure the tree would be healthy. I then replanted into a new pot with new soil. For the soil, I used sifted diatomaceous earth (Napa 8822). The drainage and retentiveness of the 8822 makes it a good soil component. I have also used this with regular potting soil in a 1:1 mixture as well if I want a little more moisture retentiveness.

The tree started leafing out the past few days. After doing the root work, I did not want to risk the tree freezing so I have it in my attic near a window that gets good sunlight throughout the day. The first three photos were taking over a period of three days. The second three photos were taken a week after the third photo, then another two weeks, and then two months later, after I had moved the tree back outside. I am letting the tree grow out this summer to thicken the trunk up.

 August 20, 2019: (Age 1yr, 4m)

After letting this tree grow out the majority of the summer, the result is some nice compact foliage and smaller leaves. If you look at the last of the photos from the previous series, you will see some yellow tips at the corners of the leaves where new growth was sun-scorched after removing from the shaded attic to outside.

As this tree grew, I clipped off individual older leaves as newer leaves grew in to reduce the strength of the growth. This seemingly kept the leaves from this otherwise often-maligned species nice and small. The tree has been in full sun throughout summer. The tree is still growing strongly. I recently applied my last round of summer fertilizer at a strength of 14-14-14. I was surprised at how quickly this tree formed a rough bark on the trunk.

October 19 / November 8, 2019: (Age 1yr, 7m)

A few shots with some fall color from October.

For whatever reason, none of my trees this year had much autumn color. I think it has something to do with watering and fertilization. I hope to rectify that this year. The bark on the lower part of the trunk gained a nice texture over the course of the year. At the beginning of the year, the trunk had a reddish brown hue with small nodules of bark formation. At the end of the fall, the trunk had fully lignified and the reddish twiggy trunk formed a grayish bark lower on the trunk. The top of the trunk retained the reddish hue.

March 11, 2020: (Age 2yr)

Trees are beginning to come out of dormancy so it's a good time to repot.

Interesting amount of roots compared to the repot last year. I cut about seventy-five percent of the roots off to get a nice clean root structure. I also removed roots growing downward and which were high up on the trunk to maintain the proper 'root plane' where a strong impressive nebari will form. 'nebari' refers to the flaring root formation at the base of a bonsai tree. It is regarded as one of the most important design components in the tree.

After cleaning up the roots, I repotted the tree back in it's pot for this coming season.

My main goal for this tree at the moment is getting it into the spring healthy. I will wait to fertilize until I begin to see new growth. Fertilizing now could damage the tree. As I did last year, this tree will remain above freezing for the remainder of the year. Ideally, it will be out in the sun on days where temps are in the forties. 

Sept 26, 2020: (Age 2yr, 6m)

Left: Shortly after repotting the tree had a strong flush of new growth. Through summer, in full sun, the tree put on a decent amount of growth. There was a nice amount of growth in the trunk especially. 

Right: Tree as of today. I have been fertilizing with Espoma Plant-Tone, an organic fertilizer with a 4-3-3 NPK. 
Left: Close up of the textured bark on the lower trunk. 

Right: Next spring, I may cut the tree back to one of these two lower branches. I think the left branch will give more movement and interest. The tree will also need to be repotted. This tree grows roots incredibly fast.


Mrs Elizabeth MacKinnon said...

Thank you for all this comprehensive information. It has helped me to identify my little sapling I grew from a seed found in a London park.

Orion said...

Glad that you were able to figure out what your seedling was. Thanks for reading.