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How do I prune overgrown shrubs and hedges?
You can give tall, overgrown and leggy deciduous shrubs and hedges a new lease on life through renewal pruning. Renewal pruning involves selective removal of the oldest, heaviest stems as close to the ground as possible. On deciduous shrubs and other plants this pruning will stimulate new shoots to grow just below the pruning cut at ground level. There, new shoots will give you dense vigorous growth. If you use a "haircut" pruning method, not only do you destroy the natural form of the shrub but new shoots grow up just below these pruning cuts. This gives you taller and more leggy plants.
The proper timing of renewal pruning is important. Severely overgrown shrubs will respond best if pruned in early spring just before new growth begins. Badly neglected, overgrown shrubs should be pruned gradually over 3 years. Remove only one third to one half of the old heavy stems each year. This will allow new shoots to develop. After renovation or to maintain plants not yet overgrown, regularly remove two or three of the older branches each year. Maintaining shrubs this way will keep them attractive, vigorous and healthy. Some shrubs which respond well to renewal pruning include spirea, forthysia, lilac, honeysuckle, mock orange, and willow.