How and when to prune new Moonrise Maple and protect from deer over winter

Asked September 8, 2018, 7:03 PM EDT

This single stem Moonrise Maple was planted in our front yard in July at 5'-0" tall, and is leafing out and growing well; purchased from Green Value in Hugo. Most of current growth is below 48", which we want to eventually prune off to make this a shade tree. When is it advised to prune? How much can be pruned the first year? Last summer we planted a multi-stemmed Acer Truncatum. Because it was multi-stemmed, we couldn't wrap it in the typical tube; the rabbits got what was close to the ground and the deer ate everything from the top down. We lost the tree; the Moonrise Maple is the replacement. Full sun, SE and SW exposures. We have bought 3' wood stakes and chicken wire, and wonder if the best way to protect our new tree this winter is to place a chicken wire fence around it, perhaps 6 foot diameter. Because we've already lost our large Sugar Maple from interior rot we discovered after we bought our house in 2001; then lost the 5' A. truncatum last year; we really want to protect and nurture this new Moonrise. Your help is greatly appreciated! Here's a photo taken today.

Ramsey County Minnesota

3 Responses

Moonrise maple (Acer shirasawanum 'Munn 001') is a cultivar of Japanese maple and is listed as hardy in zones 5-9. Ramsey County is in zone 4, so unfortunately I cannot recommend this tree with confidence for a Ramsey County location. You will likely see winter dieback (dead branches and branch tips) that will require pruning in spring, and the tree may very possibly die due to cold temperatures and freeze - thaw cycles we experience often in later winter / early spring (when temperatures fluctuate from warm winter days then drop to very cold nights). It is also a small tree - 8-10 feet - so I would not count on it as a replacement for your sugar maple / a shade tree.

If you want to go ahead and try to grow it in your landscape - and I totally understand if you do - you will want to protect your tree with a wide circle of fencing. We recommend hardware cloth, sturdy galvanized wire fencing with 1/4" square openings that prevent rabbits from eating through the wire or accessing the plants enclosed. Place your stakes around the tree about 4-6" out from the longest branch. Create an enclosure with the hardware cloth on the outside of the stakes and wire the ends together creating a circle of fencing. Bury the bottom 3" of wire in the soil around the tree to prevent animals from crawling underneath the fencing. Your fence should be a minimum of 48" for rabbits because they are light enough to sit on top of snow, but because you also have deer issues, you should go taller if possible. You can always wire two coils of 48" hardware cloth together to create about an 8-ft tall fence. Use wire or zip ties to anchor the fencing to the stakes.

You can put up the fencing almost any time now and plan to remove it when the soil thaws and you can easily pull out the stakes and fencing. You may want to try some deer repellents to reduce deer browsing in spring. Start applying early in spring to "train" the deer to leave this plant alone. Change your repellent to a different kind every 3-4 weeks as deer can get used to a repellent. Remember: a hungry deer will eat almost anything, so repellents only dissuade them, but are not guaranteed to completely repel them.

Protect the root zone of this tender tree with a circle of shredded wood mulch about 6-feet in diameter. Mulch holds in soil moisture, moderates soil temperatures (that freeze-thaw cycle again) and protects the roots from damage. Mulching a tree root zone also eliminates the need to mow around and on the roots and close to the tree trunk which can cause mechanical damage to the trunk and compromise tree health.

Maples also tend to need soil with an acidic pH and organic soil. A soil test can be helpful in determining the qualities of your soil. You may need to fertilize your Japanese maple with a fertilizer for acid-loving plants. You can consult with your garden center professionals for options.

Just a gentle reminder that in the future to be sure to choose plants with growing requirements that match your site conditions - cold hardiness zone, soil pH, soil type, etc. Best of luck with your tree - I hope you are successful.

Thank you, Julie, for your time and care in responding to my questions. I discussed zone questions with the supplier and my family-owned garden store before buying the tree, and also was told of others' success with this tree in our area. It may not make it, I now realize more fully.

When will it be optimal to prune lower branches? How cautiously should pruning be approached so as not to shock the tree?

Thanks again!

I would wait to prune it in early spring. It may "bleed" some sap at that time, but that is normal. In the spring, you will be able to address pruning out any winter kill at the same time, and the tree will have the benefit of a full growing season to recover from any pruning shock. More importantly, if you prune it now, the act of pruning prompts the tree to actively put out new growth where you made a cut. We want to avoid that as we want the tree to start gradually going dormant for winter. Any new growth now may not have enough time to harden off (deacclimate) before winter cold sets in.