Petunias are generous bloomers, but they’re also hungry plants. A pot or hanging basket that looked lush in spring can turn leggy and flowerless by midsummer if the soil runs out of nutrients. Many gardeners reach for coffee grounds as a free fix, though they’re not the only option, and they don’t suit every plant. If you’d like to feed your petunias naturally, there are gentler, easier choices that most home gardeners already have or can find cheaply. Here are three worth trying, along with a few tips to make them work.
Petunias bloom continuously for months, and all that flowering takes a lot of energy. Plants in pots use up nutrients faster, and watering washes them out of the soil, so container petunias need more feeding than those in the ground. Signs that your plant is hungry include pale or yellowing leaves, slow growth, long stems with few flowers and smaller blooms. Natural fertilizers release nutrients more slowly than synthetic ones, so they’re kinder to roots, but they work best when you feed little and often rather than heavily and rarely. If your petunias are green and healthy but short on flowers, bone meal can help. It’s a slow-release source of phosphorus and calcium, and phosphorus is the nutrient most linked to blooming. Mix a small amount, roughly a tablespoon for a medium pot, into the top layer of soil and water well. It takes weeks to break down, so apply it once at the start of the season and again partway through. Keep it away from pets, which are often drawn to the smell, and use it sparingly, since too much can build up in the soil. Natural fertilizers work best alongside good basic care. Give petunias at least six hours of sun, water at the base of the plant, and let the top of the soil dry slightly between waterings. Pinch off faded flowers and cut back leggy stems, which encourages fresh buds. Avoid heavy feeding with nitrogen-rich materials, which can give you lots of leaves and fewer flowers. If you’re not sure what your plant needs, start with compost, watch how it responds for a few weeks, and add one more option only if it needs it.
