Today I transplanted a Ludwig Spaeth lilac tree-bought at a garden center. The version is one which has the lilac grafted on to a tree trunk – the overall plant is about 7 feet high with a trunk about 2.5 inches in diameter. Branch spread is about 3 feet high and 3 feet wide. It was transplanted to a backyard in Toronto around the Dundas Ossington area. It is a sunny backyard but the sun would be on the tree mainly in the first half of the day. I was advised to only leave about 2-3 inches space around the outside of the root ball so the tree would stand firm. . I did use Triple Mix underneath the plant root ball (several inches) and Triple Mix to fill in around the sides. My questions = 1) Can you use too much Triple Mix compared to native soil such that it will be detrimental to the roots thriving? Should I be using a 50/50 mixture or something similar? 2) How often do I water and how much water should I use? 3) Should the top of the root ball be even with the top of the existing ground? Many thanks to anyone answering these questions and any other advice would be appreciated- Thanks again!
Thank you for contacting the TorontoMaster Gardeners with regards to your Ludwig Spaeth lilac tree.
This tree does best when grown in average, medium moisture, well-drained soil in full sun. It will tolerate some light shade, however it flowers best in full sun.
Whenever planting a tree it is important to assess your site location in regards to space and surrounding structures, light conditions, soil type and moisture and drainage. Dig a hole in the new location that is two times wider than the root ball and at the same depth.
The following information is from our Gardening Guide, Planting a Tree For Life,
The importance of planting a tree at the correct depth cannot be overemphasized. Planting too deeply will eventually lead to the death of the tree. The place where the roots meet the trunk is called the trunk flare or the root collar. Unlike roots, trunks are not meant to be buried in soil. If covered in soil the trunk may rot, become diseased or even die. The tree must be placed in the ground so that the soil grade is level with the bottom of the root collar. When planted at the proper level you will see the gentle flare of the trunk rise just above the soil line. Err on the side of placing the tree higher above the soil, especially if you suspect the soil will settle and the tree will sink. It is easier to add soil after planting, than to replant a tree with a sunken trunk flare.
You also mention that you added triple mix to the planting hole. Ideally you should not add new bags of soil or soil amendments to the planting hole when planting a tree. From our Gardening Guide:
It may seem nurturing to add new top soil, manure, compost or peat moss to enhance the soil, but in fact, you are creating a soil pocket which is unlike the surrounding soil. The roots may initially grow well, but, as they come to the edge of the soil in the planting pocket, they will resist growing beyond into the surrounding soil. The tree will be stronger and grow faster if its roots are able to adapt quickly to the given soil conditions and begin to grow out and down into the earth beyond the prepared hole. If you would like to improve the soil, do so gradually by using organic amendments, such as a layer of disease free leaves, in the form of a mulch. Spread mulch around the surface of the soil after the tree is planted, so it will slowly and naturally decompose and work its way into the soil.
Lastly, it is important to water your tree regularly for the first few years of your tree’s growth, checking to make sure the soil has not dried out. If there is not much rain, gently pour two large buckets of water over the soil once or twice a week or let the hose slowly trickle down the same amount of water. However, don’t overwater. If water is pooling around the tree and the soil is very wet, cut back on your watering and water less frequently.
The Toronto Master Gardeners Garden Guide on Planting A Tree for Life has all the information you require to insure that your tree thrives.
Good Luck.