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These Kitchen Scraps Will Help Your Petunias Thrive
By KALEIGH BRILLON
Petunias are fairly easy to care for, but they'll benefit from fertilizer every week or two. Instead of regular fertilizers, you can use ground coffee and egg shells.
Coffee grounds provide small amounts of nitrogen, phosphorus, and potassium, which make up fertilizer. They also provide low doses of iron, copper, calcium, zinc, and magnesium.
They also feed microbes, which help improve soil drainage over time, but too much caffeine can slow or stunt plants’ growth, so only use a ½ inch of grounds per 4 inches of soil.
Coffee grounds will repel and kill snails and slugs, too, as will a coffee spray containing two parts brewed coffee and one part water applied directly to the slugs and foliage.
Eggshells provide calcium — without it, petunias’ cell walls and membranes won't form correctly. The plants like a pH of 6.0-7.0, but if the soil is acidic, you can add eggshells.
Rinse and dry the shells completely and grind them in a coffee grinder until there are no large chunks left. Mix it into the soil around existing petunias or before you plant them.
You can also boil eggshells in water and let them sit overnight. Remove the shells and spray the water on your petunias, especially to treat botrytis, but test it on a leaf first.