Japanese Ivory Silk Tree

(Question)

One yr old tree that had a rough start last year due to low rainfall.It lost all its leaves early.It managed to survive but did not produce any flowers this year.It doesnt seem to be qrowing mucn and my main concern is the leaves are very pale.Our soil is mainly clay.We dug a foot below and around the root ball and filled in with triple mix.The tree is in full sun 6-8 hrs a day.Should the soil be tested?I know my rhododendron gets yellow leaves and I add an additive and this helps.HELPs

 

(Answer)

Thank you for getting in touch with the Toronto Master Gardeners about your Ivory Silk Japanese Lilac tree. There may be a couple of issues that have caused the problems that you describe.

You mention that your tree had a rough start last year (2016) due to low rainfall. Did you rely on rain to keep it watered after you planted it or did you water it regularly to make sure that it could establish a deep, extensive root system? Transplanted trees require consistent and deep watering for the 1st year, especially during drought conditions. It’s also important to make sure that it has sufficient water before the ground freezes. However, it seems to have managed to survive. There has certainly been ample rainfall this spring.

You express concern that your tree did not produce any flowers this year; it is not uncommon for a young transplanted tree to not produce flowers the first year. However, the fact that you describe minimal growth and pale leaves indicates that the tree may have problems related to how it was planted. First of all, “the size of the hole should be at least twice as wide as the current container – wider is even better. The purpose is to loosen as much surrounding soil as possible so that the roots can easily grow while absorbing plenty of water, nutrients and air.” It is recommended that “the hole should be as deep as the container.” Digging a deeper hole may result in the tree being planted more deeply than it should be–that could eventually lead to the death of the tree.

Did you backfill with the soil that was removed when you dug the hole for the root ball or did you mix in the triple-mix?  If one were to incorporate an organic material to help loosen the clay soil for better drainage, triple mix might not be the best choice. Even though Ivory Silk Japanese Lilac trees will tolerate clay soils, they prefer well-drained soil to allow air and water to permeate more easily.  We would suggest that using a mulch of compost or leaves on top of the soil around the tree would help to create a soil with better drainage. It is doubtful that your soil needs to be tested–it just needs to be amended.

Did you loosen the roots of the tree after removing the tree from the pot? One can simply pull roots apart with one’s hands so that they can be arranged for optimal growth. “If a tree has been in a container too long, the roots may hit the pot edge and begin to grow in a circle. When they run out of room, they become matted and tangled. If you plant the tree, leaving the root ball matted, tangled and growing in a circle, the roots will strangle and eventually the tree will die.”

If your tree has been planted properly, you might consider applying a 2-3 inch mulch around the tree, making sure that it is at least 6 inches away from the trunk. Fertilizing the tree in the spring would help to encourage good growth; fertilizing it now might still be helpful for the tree; however, do not fertilize in the fall as new growth may suffer during the winter months. If the tree doesn’t seem to improve, you may have to consider digging it up and replanting it, preferably on a cool, cloudy day–maybe during the early fall–and take into consideration the tips in the TMG Garden Guide on planting trees.

For more information, please read this Toronto Master Gardeners’ Garden Guide: http://www.torontomastergardeners.ca/gardeningguides/planting-a-tree-a-toronto-master-gardeners-guide/

We hope that your Japanese Ivory Silk lilac will continue to grow successfully.

Planting a Tree: A Toronto Master Gardeners Guide