Fertilizing a tomato plant may sound difficult but really it is extremely easy, and quite rewarding in the end. The leafy green tomato plant can provide an attentive gardener with a summer's worth of bounty for salads, sandwiches, soups and salsas. But providing all of this fruit is hard on a tomato plant; it requires a significant amount of fertilizer to keep it healthy and productive. Choosing the right fertilizer for your plant requires a bit of skill and study, but once you're determined the right mixture for your plants, you'll be ready to begin growing luscious tomatoes in your garden.
Before planting season begins, take a sample of your garden's soil to your local gardening store or extension office, and ask them to test it for you. A soil sample test will tell you if the soil in your garden is naturally deficient in a particular type of nutrient that your tomato plants require. Having this knowledge will allow you to choose the perfect fertilizer for your plant that corrects this deficiency.
If your soil is normal, look for the ratio of fertilizer on the commercial fertilizers before you buy. Fertilizers list their ratios of nitrogen, phosphorus, and potassium in a standard format (N-P-P). Tomatoes growing in normal soil require a 1-1-1 ratio. Beware of garden fertilizers high in nitrogen. These fertilizers will produce abundant leaves and little fruit.
Apply fertilizer when you are planting your tomatoes. Dig a hole 3 inches deeper and 2 inches wider than the root ball of your plant. Put 3 to 4 tablespoons of fertilizer into that hole, along with your new plant. Water your new plant to help it absorb the fertilizer.
During Crop Season
When your first tomatoes have formed, but are still small and green, apply more fertilizer. Dig a narrow channel 1 inch deep, 5 inches away from the stem of your plant. Apply 1.5 teaspoons of fertilizer into this channel. Cover the fertilizer with an inch or two of soil. Water your plant normally. Repeat this process every 3 weeks as your plants grow and bloom. You may only need to do this once or twice per season. Always apply your fertilizer with care, and avoid getting any fertilizer on the leaves of your plant. Fertilizer can burn the leaves of a tomato plant when the two come into direct contact with one another.
If you're uncomfortable with using conventional fertilizers, you can work with organic choices, such as dried manure and bone meal. These fertilizers aren't optimized to provide a complete ratio of nitrogen, phosphorus, and potassium (N-P-P), so you will need to apply these fertilizers with care. Dried manure is low in phosphorus, for example, so you could add bone meal to the mix to help feed your tomatoes more completely. Organic compounds are great because they break down slower than commercial fertilizers, so you may be able to apply them less frequently. Supplement your organic fertilizers by applying a spray of fish emulsion or seaweed every 2 weeks, to provide your plants with trace nutrients they may be lacking.