NDSU Extension - Ramsey County


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July 13, 2015 Horticulture Column

Garden Home Remedies

When diseases or pests attack our gardens, we commonly reach out to our friends for advice on what to do. This article explores some of the most common “magic cures” for our plants.  These are not proven however seem to have had some success.

Coffee Grounds as Weed Killer and Fertilizer

Some gardeners sprinkle fresh coffee grounds on the soil. The claim is that it works as a fertilizer, lowers the soils pH and suppresses weeds. Science shows that fresh grounds are acidic and won’t change the soil pH. They may suppress weeds; however, some plants such as tomatoes will be negatively affected. Some fungal pathogens may be suppressed by coffee grounds.

Coffee Grounds Recommendation

  • Don’t uses as a mulch
  • Use coffee grounds as part of your compost (up to 20%)

Dish Soap as Insecticide

The claim is that mixing 1 to 4 T dish soap per gallon of water can control aphids.  In reality it works because it washes off the waxy cuticle. The downside is that it washes off the waxy cuticle of plants too and is too harsh. Commercial insecticidal soaps are less likely to harm plants. However, they may be a less effective in controlling aphids than homemade concoctions.

When dealing with insect pests in our gardens and yards, it is important to first identify the culprit. Look at the underside of the leaf for predators. Sometimes you may need to go out at night with a flashlight. Once you know what is eating your plants, then you can use the appropriate treatment without harming the plants.

Hot Peppers as an Insecticide

The claim is that spreading ground up hot peppers on plants will control insects. A spray made with a few tablespoons of Tabasco added to a gallon of water, plus 1 tablespoon of dish soap is applied.

Hot Pepper Reality:

  • Deters insect damage on leaves
  • Effective against white flies and mites
  • Insects will move to unsprayed plants
  • Doesn’t appear to damage plants
  • Remember that it acts as a repellant-not an insecticide
  • Need to reapply often
  • Commercial capsaicin sprays last longer

Beer to Control Slugs

In reality, beer does attract some slug species within a few feet. To work, you must have the right shape of bowl. Reducing the humidity under plants by keeping the area clean is more helpful. Diatomaceous earth works; however, its effectiveness is reduced when wet. The best remedy for slugs is using a product containing iron phosphate such as Sluggo or Escar-Go!.

In conclusion, before treating your plants, do your homework. Investigate the claim and explore how it works and if they will affect plant growth. When using commercial products, read labels carefully before using.


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