Answer: Pruning a shrub back after it has outgrown its spot can be quite difficult. It's better to pinch and prune on a continual basis than to allow a plant to put out two-feet of growth and then attempt to reduce its size. It might be better for your plants to relocate them to another site. If that's not possible, you can remove up to half of the new growth without causing too much stress. As it puts out new growth, continue to reduce it by half. This will keep the shrubs at roughly the size they are now.
Root pruning is an excellent way to retard growth so you may want to try this technique. Root pruning is done by inserting a spade or shovel into the soil to the depth of the blade. The dripline is where you'll insert the shovel. Make alternate slices into the soil around the dripline, spacing each about a shovel blade's width. In 2-3 years, repeat the root pruning, plunging the shovel down in areas where you didn't sever the roots during the previous root pruning session.
Best wishes with your landscape!
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