Answer: Lilacs are fairly hardy plants and even the smallest sucker will grow into a full sized plant in just a few years. If you're digging suckers that are growing from roots near the mother plant, you can dig them at any size. The leaves should look healthy - sometimes new leaves are tinged with purple as they unfurl, but later turn green. When digging, use your shovel or spade to dig through the roots between the parent plant and the sucker, then just dig the sprout up with some roots attached. If you place your transplants two feet apart, they'll fill in quickly. The mature plants should be 6 to 8 feet apart to give them room to grow, but you can start the plants closer and then move every other one as they begin to fill out. Lilacs like a slightly alkaline soil, so use any organic matter except peat moss to amend the planting area. Be sure to supply about an inch of water per week to your new transplants, to help them get off to a good start.
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