Tomatoes (Solanum lycopersicum) are one of the most commonly grown vegetable garden plants due to their variety of functions in the kitchen. Whether you're growing large slicing tomatoes for burgers and salads or growing sauce tomatoes for an Italian feast, fertilizer requirements are the same, but there are a few other factors that lead to healthy harvests.
All fertilizers have a three-digit number printed somewhere on the package. This number is known as the N-P-K ratio and tells you what percentage of nitrogen, phosphorus and potassium is in the fertilizer. These three nutrients are the most commonly deficient in soils and the three that plants need the most, including tomatoes. While each of these nutrients has a long list of benefits to plants, a basic breakdown is: nitrogen is responsible for strong, green growth; phosphorus aids in bud, bloom and fruit production; and potassium is pivotal in water uptake.
If you choose to forgo a soil test -- although it's highly recommended for accuracy -- apply a complete fertilizer that is high in phosphorus and low in nitrogen. Look for an N-P-K ratio of 8-32-16 or 6-24-24 for optimum results. Apply this type of fertilizer at a rate of 1 pound per 100 square feet. These ratios are sometimes harder to come by in nurseries and garden centers; if you can't find these ratios, choose a fertilizer with 5-10-5 or 5-10-10, which are much more common. Apply these fertilizers at a rate of 2 cups per 100 square feet.
Tips for Choosing
Nurseries and garden centers often have rows upon rows of different types of fertilizers, including organic and synthetic, granular and liquid. Some fertilizers are specifically marketed to different applications and chances are you'll see one designed specifically for tomatoes. Even if the fertilizer is marketed for tomatoes, still look at the ratio. Other fertilizers to look at during your search are those designed for flowers or vegetable gardens, sometimes called "Bud and Bloom," "Vegetable Garden Fertilizer" or something similar. These often have the high levels of phosphorus needed by tomatoes because this nutrient helps produce bigger, healthier buds, blooms and fruit.
Other Growing Tips
Tomatoes grow best in alkaline soil with a pH around 6.5, although slightly above or below this won't be detrimental if other conditions are met. They also require full sun and consistent moisture. Add organic material into the top 8 inches of soil to improve drainage. Consistent moisture is pivotal for tomatoes: those that don't receive consistent moisture, such as during a drought or from watering too much during different parts of the growing season, may develop blossom-end rot or other problems.
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