HI chic3 YES your spirea be divided in half.
Spirea when divided every few years will becoming stronger and produce more blooms.dig up half the plant soil and all or dig up the hole plant and divide it into sections of the desired size do not make them to small. make sure you get plenty of roots with with each section.spirea can be divided in very early spring.but is best to divide the plant in the fall after it has bloomed and the heat of the summer is past.dig the new hole where the plant will be placed larger than the root system of each division so the root system will have lots of new lose soil to spread out new roots.add water into the hole then place the plant in.then backfill with soil.then water the plant real well.water it about every two weeks till the roots take hold.hope this helps and good luck with you spirea.your friend in gardening.mike57

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