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Garden Guru

Horticultural Oil

Jim Boxberger
Posted 5/9/25

Last week was all about No Mow May, but another big contributor to the downfall of bee populations is the use of pesticides. Every year commercial operators spray tons of product on farm crops to …

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Horticultural Oil

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Last week was all about No Mow May, but another big contributor to the downfall of bee populations is the use of pesticides. Every year commercial operators spray tons of product on farm crops to keep all manner of insects at bay and this affects honeybees as well. But there is a spray that you can use on your trees and shrubs that won’t hurt honeybees as long as you know how and when to apply it. Horticultural Oil Spray is safe for use on trees and shrubs as long as you don’t spray it on when the plants are blooming as that will affect the bees and other pollinators. The purpose of the oil spray is to cover and suffocate insects and insect eggs. Back in my grandfather’s day, he used what was called dormant oil or Volck Oil during the winter months to suffocate insect eggs that had been laid on the bark of his trees and shrubs. Dormant oil could be sprayed anytime after the leaves had fallen until late March when new growth would start to appear. Today’s horticultural oil is much more refined and therefore can be used as a dormant oil of the winter to suffocate eggs and used during the season to control insect infestations. Oil spray won’t bother your pollinators as long as you follow a few rules. Never spray when the plant is flowering, that is when your pollinators will be visiting. Don’t spray on a windy day as overspray and drift could affect pollinators nearby. If possible spray early in the morning or late in the evening as most of your pollinators will not be active at those times. Neem based oil sprays are generally organic and unless sprayed on the bees will not harm them once it is dried on your plants leaves. Typically, your spraying the leaves of the plants to protect from sap sucking insects and bees don’t care about your leaves, they are all about flowers. Neem oil is also better for other pollinators like butterflies too. I know I talk a lot about bees, but what’s good for the bees, is good for the butterflies too.

Also now that we are in hummingbird season again, I always get asked about which red flowers are the best to attract hummingbirds. Well of course red salvia is at the top of the list, but I hate to burst your bubble, but hummingbirds don’t care about color. We have a dark blue trailing salvia called hummingbird falls that we sell in hanging baskets and because the shape of the flower is just right it is a hummingbird magnet. It is more about a flower with a deep throat than it is about color. Bees like flat face flowers, like daisies and dandelions, as it is easy to collect both pollen and nectar. While butterflies and hummingbirds like deep throat flowers like salvia and scaevolas where it is difficult for bees and other pollinators to collect the nectar. Both butterflies and hummingbirds have long feeding devices that help them to collect nectar from these deep throated plants. Hummingbirds have their long beak and butterflies have their Proboscis, a long straw like mouthpiece. Think of a Proboscis like one of those New Years Eve noisemakers that when you blow out they unroll and when you stop they recoil back up, it’s a lot like that. So if the shape of the flower is more important than the color, why are most hummingbird feeders red? Marketing 101, red attracts consumers better. Hummingbirds don’t buy feeders, we do, and there you have it. Come in and we can show you what flowers will be the best for attracting hummingbirds and don’t worry, they don’t have to be red.

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