(Question)

Hi there! I have a two year old Japanese Maple ‘Omurayama’ in a raised bed tucked up against a corner of my house. There is a three foot high wall enclosing it. We need to get a portion of our foundation waterproofed which means they will be taking down part of that wall and digging out the dirt that is up against the house – right around the J. Maple. Today we dug out the J. Maple with as big a root ball as we could manage. Luckily tonight the temps are above freezing. We wrapped the root ball in plastic and have it leaning against a different fence. Do you have any advice about keeping the tree comfortable until we can replant it in a few days or up to a week? We didn’t water it before hand. Should we water it in its plastic swaddle that we have it in? Or should we leave it alone? Also – when we replant, are there any special instructions you can share? I have never planted anything like this so late in the season. As always – thank you!

(Answer)

Thanks for contacting us with your question about digging up and transplanting your Japanese Maple.

It is actually quite fortunate that you are transplanting at this time in late fall, as the plant is likely dormant. Early spring is also a good time. Both of these times place less stress on a plant, whether it is a tree, shrub or perennial (for perennials you can transplant any time from early September to late November as long as the weather has cooled and the ground is not frozen, and then again as soon as the ground has thawed in spring (early April or later). Perennials have a much smaller root system than trees or shrubs, but optimal transplanting times are not too different for any of these.

Because your tree is only a couple of years old and Japanese maple roots are fairly shallow, when you dug up the plant you likely would not have significantly damaged its roots, especially fine feeder roots that are close to ground level. These extend about as far as the tree’s canopy.

I would recommend now giving your tree a good dose of water [but not overwatering] to help it get over the shock of being dug up, and then placing it in a sheltered spot such as a garage or shed until you are ready to place it back in its home. At this time, the lack of light will not be detrimental as the plant is in a dormant state, but a slightly warmer temperature than your garden would be beneficial, especially if cold temperatures are predicted for the next week. Remember that when you transplant it into the ground it will be slightly warmer than it is above ground, so try to mimic those below-ground temperatures. Do not place it in a really warm environment such as inside your house. Instead of keeping it in plastic, which will prevent air from getting to the roots, just place it loose in a bucket or other container, once you’ve watered it. Don’t keep it in standing water.

Obviously, the sooner you can transplant it back into its home the better, but a week or so would probably not do too much damage.

Once you’ve transplanted it, water it well (once a week or so) until freeze-up – i.e. when the ground is frozen to at least 6-10 inches. After that, watering will not make a difference. Do not fertilize. In the spring, once the ground is thawed (i.e. late April or so), apply one inch of compost and give it some water once a week until you see it leafing out. You can then reduce watering to every couple of weeks. Then resume your regular watering schedule and/or wait till warmer weather to water again. In the fall, give it another inch of compost.

When applying compost, do not put the compost right against the trunk. Instead, create a well with a compost ring around the tree sloping inwards; this will help rain water drain inwards towards the tree. You can lay some broken up garden twigs and green trimmings in a 2″ layer around the base of the tree (but not touching the trunk); this will help retain rain water and prevent it from running out away from the base of the tree.

If it gets to a point where your work is delayed and the ground becomes frozen, don’t panic. Just pot up the maple in a pot big enough to accommodate the root ball and keep it in an unheated but protected space such as a garage or shed, or wrap in multiple layers of bubble wrap and/or burlap and place in a sheltered spot away from harsh northwesterly winds. You could even bury the tree, pot and all, in an otherwise unused part of your garden. Keep it on the dryish side so as not to drown the roots.

Keeping it in a garage or shed may be better to protect the tree from freeze and thaw cycles which can be damaging. But if you need to put it in the ground, just heap some branches (maybe conifer branches from your Christmas tree if you celebrate Christmas) – this will protect it from freeze and thaw cycles till late April.

You can then transplant it in spring,

These resources may be helpful:

Transplanting a Dwarf Japanese Maple [Toronto Master Gardeners]

Transplanting Japanese Maples [University of Washington]