Tomato plants thrive when grown in composted soil that drains well. They do not do well when overfertilized because it encourages lush foliage growth at the expense of setting fruit. A side dressing of fertilizer added when the plants are between 5 and 10 inches tall encourages strong stem and branch growth. Heirloom tomatoes are indeterminate-type plants that can grow 8 to 10 feet in length and give fruit the entire growing season. Using compost as a fertilizer for heirloom and hybrid tomatoes also increases their nutritional value, according to a 2007 study at the University of California at Davis.
Homemade Compost Fertilizer
Tomato plants receive the nutrients from compost as the plant needs them. The nutrients from decomposed organic matter in compost cycle from the soil through the root system to the growing tomatoes in response to the plant's needs. Synthetic fertilizers release a sudden burst of phosphorus, nitrogen and potassium to the plant that the plant may not be able to absorb all at once. Compost works in synergy with the plant. Homemade compost is the least expensive tomato fertilizer available. It is easily made from kitchen and yard wastes put into a commercial compost bin or a simple pile. Water and air help create the decay process, and compost is finished in three to six months.
Commercial Natural Fertilizer
Commercially available natural fertilizers add billions of microorganisms to the soil to assist tomatoes in healthy growth. Microorganisms create soil that is nutrient-rich. Fish bone meal, feather meal, kelp meal, mined potassium sulphate and alfalfa meal provide the microorganisms in natural fertilizers. Soil that is subjected to synthetic fertilizers becomes dry, grey and lifeless over time. Erosion problems are created by lifeless soil. Commercially available compost fertilizers have high organic matter content so they contribute to the revitalization of soil. Tomatoes grow well in soil that has high organic content.
Worm Compost Fertilizer
Tomatoes need high phosphorus content in fertilizer to set blossoms and fruit. The National Garden Bureau suggests using a fertilizer with higher phosphorus than nitrogen content, such as worm compost products. Worm compost has seven times higher phosphorus content than common garden soil. There are many organic fertilizers that are based on vermicompost available at garden centers. Worm compost is added to tomato plants as a side dressing fertilizer before the fruit sets. Worm composting is often taught in local city recycling programs because it is small and easy to manage for urban gardening.