Epsom salts contain magnesium, which is often lacking in acidic soils. This mineral can increase fruit set on blossoming crops, such as tomatoes, peppers and eggplants. Try it on blooming flowers, such as roses, as well. Mix 1 tbsp. Epsom salts with 1 gallon water. Water plants with this solution once a month during the growing season.
Put those leftover coffee grounds to use in the garden. The grounds are a good source of potassium and phosphorus, according to "Sunset Magazine," the two nutrients responsible for blooms and fruiting. Spread 1 inch of coffee grounds over the soil and till to a depth of 6 to 8 inches before planting, or side dress plants with a 1/2-inch layer of coffee grounds. Better yet, add coffee grounds to your compost pile along with plant and food scraps for a balanced, slow-release fertilizer.
Sprinkle fireplace ash around flowers and vegetables for a quick source of potassium. The ashes also supply calcium carbonate, which promotes blooms and may reduce blossom end rot in tomatoes. Use fireplace ash sparingly, though, because it can damage soil when used in excess. Do not use fireplace ash on alkaline soils.
For a complete, organic fertilizer, mix 4 parts seed meal, 1/2 part dolomitic lime, 1/4 part gypsum, 1 part bone meal or rock phosphate and 1 part kelp meal in a large container. Spread 4 quarts of this mixture over 100 square feet of garden space along with 1 inch of manure of compost in the spring and till to a depth of 6 inches. Side dress established plants with 1 inch of the mixture. This organic fertilizer provides slow-release forms of nitrogen, phosphorus and potassium, as well as trace minerals and growth hormones. If your soil is very alkaline, reduce or eliminate the dolomitic lime and gypsum, which raise the pH level of the soil slightly.