Vinegar
Some plants, such as azaleas, gardenias and rhododendrons need acidity to get soluble iron. If you live in a hard water area, these plants suffer from excess lime, causing the leaves to turn yellow. To compensate for this, add 2 tablespoons of cider vinegar to a quart of water. Pour a cupful or so around the base of the plant every two or three weeks until the yellow goes away.
Soft Drinks
Soft drinks containing citric acid control development of microorganisms that can block the plant’s water conducting vessels. A molecule of water can move from the base of a 24″ cut rose to the petals in 30 seconds or less. The cells of the stem of a rose, which carry the water, are like a handful of soda straws. The liquid can only be drawn up the ‘straw’ as long as the straw is clean. The Michigan State University’s Department of Horticulture recommends mixing a solution of one part water, one part soft drink, then adding 1/2 teaspoon of chlorine bleach to each quart of solution.
Lemon Juice
Get more mileage from your cut flower arrangements with this homemade preservative: Use two tablespoons of fresh lemon juice, one tablespoon of sugar and 1/2 tablespoon of household bleach, added to 1 quart of water. Place flowers in this mixture.
Epsom Salts and Borax
Home gardeners who raise melons often complain about a flat taste, even if the vines get plenty of sun and plant food. Quite often the trouble is due to a lack of magnesium in the soil. University of Maryland College of Agriculture tests showed that muskmelons could be sweetened by spraying the vines with a solution of borax, Epsom salts, and water. Use 3 1/3 tablespoons of household borax, plus 6 1/2 tablespoons of Epsom salts, in 5 gallons of water. Spray foliage when the vines begin to “run”, and again when the fruits are about two inches in diameter.