Answer: Peonies are usually transplanted only if really necessary because they resent being disturbed and may not bloom for several years afterward. If you do this, do it in the fall and take care to replant at the same level as it grew before. Fall is also the preferred time to divide peonies.
The lilac can be moved in the fall or in the very early spring before it begins to grow.
In both cases, water the plant the day before you move it, make sure to dig as large -- wide and deep -- a rootball as possible (it will be heavy!) and replant immediately. Water well to settle the soil and then mulch with several inches of organic mulch over the root area but not touching the stems. Water as needed to keep the soil evenly moist but not sopping wet up until the ground freezes. Water next season as well, just as you would for any newly planted plant.
Good luck with your transplanting.
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