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When to repot a budding gardenia and when not to use insecticides

For The Baltimore Sun

After years of failure, I’ve gotten a gardenia to grow and it is going to bloom! At least, it has buds. It’s growing so well, however, it is much too big for its pot. I read this is a good time of year to transplant, but I’m nervous. Good idea?

Gardenia buds are notorious for falling off, but that usually happens when it experiences temperature swings. Keep the temperature steady and cool, like the low 60s.

They flower best when their pot is a bit small. Don’t transplant until you see roots coming out of the bottom of the pot’s drainage hole and only into a pot one size larger. Transplant when new growth commences in spring and disturb the root ball as little as possible.

I stopped spraying (the insecticide) Sevin years ago because the ingredient (carbaryl) kills bees. I hear it’s got a new ingredient. Can I use it on flowers?

The new active ingredient, zeta-Cypermethrin, is highly toxic to bees and other pollinators. This type of pyrethroid insecticide is extremely broad spectrum, meaning it kills a huge number of insects including beneficials. It cannot be sprayed on flowering plants.

Because it can kill longer than the old product, it doesn’t make sense to use it on anything whose blooms open within that time period, including fruit and vegetable plants. These often require pollinators to produce crops. It is also highly toxic to fish and aquatics, so it cannot be used where it may contact water, which includes drift or stormwater run-off. This is why it’s always vital to read pesticide labels.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Maryland’s Gardening Experts” to send questions and photos.

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