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Ask a Master Gardener: Too late to fertilize, moving spirea shrubs and more

Q: In your Sept. 17 newspaper article: If "big leaf hydrangeas should not be pruned in spring because they bloom on last year's wood," then we should never prune them? Great article and thanks in advance for your answer.

A: Bigleaf hydrangeas (Hydrangea macrophylla), the type with blue or pink flowers, typically don't need pruning except to remove damaged foliage or dead branches. If the plants get old and stop flowering well, it can help to prune them to the ground in early spring. They won't flower that year, but may bloom better the following year. It is a good idea to cut off spent flowers after they've faded.

Q. Is it too late to fertilize my lawn?

A. Fall is the best time to fertilize the lawn, but stop fertilizing by mid-October. This runs contrary to some recommendations you may see. New research shows that plants take up less nitrogen with cooler temperatures. If you fertilize when it's cool outside, you're spending money on fertilizer the plants don't get, and the unused nitrogen can leach into groundwater. Choose a fertilizer that provides at least half of its nitrogen in a slow-release form.

Q: I have six spirea shrubs on the north side of my home planted along the foundation that need to be moved temporarily until a new deck is installed. If I dig out the plants now (three are more than 24 years old, and three are 2 years old), would it be better to plant them in another flower bed or in big pots and mulch them well along another foundation wall? The deck may be completed by snowfall, but replanting the shrubs won't occur until next spring at the base of the new deck.

A: When you're moving a shrub, it's best to get it into its new home as quickly as possible, but since that's not an option for you, you'll have to give them good winter protection and hope for the best. Either of the methods you're thinking of may work, but burying them is the better choice. If you have large enough plastic pots and enough space in a garden bed, you could try potting them and then burying the pots. That way they'll suffer less shock when you dig them out a second time before putting them in their permanent home. Preserve as much of the root system as you can when you dig them up, and keep them watered until the ground freezes.

There's more information about moving trees and shrubs at

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