Get Higher Yields Using Tomato Fertilizer

Gardeners are getting greater yields and larger tomatoes using a variety of tomato fertilizers.  There's several accepted methods for fertilizing tomatoes and many types to choose from. I'll cover some of the most popular options.

There are reasons some gardeners prefer to use only organic fertilizers -- they are slower acting and gentler on the environment. Commercial inorganic fertilizers do have some advantages. Chiefly, they are cheaper and take less effort to use.

Organic Fertilizers

Dr. Earth Organic Fertilizer

Organic fertilizers, derived from plant and animal products, are better for your garden in the long run. Organics will never burn plants and are longer lasting, unlike inorganics which can leach away during heavy rains. Other benefits are the improvement in the condition of the soil in relation to plant growth (tilth), and the help to fungi which aid plants in nutrient absorption. Common organic fertilizers include:

  • fish emulsion
  • blood meal
  • bone meal
  • compost and compost tea
  • manure and manure tea

Inorganic Fertilizers

What to avoid

Don't use high nitrogen content fertilizer on tomatoes. It will just stimulate leaf growth at the expense of fruit. And don't over-fertilize. This also leads to excessive green growth and few blossoms.

Also commonly used, commercial inorganic fertilizers are made from compounds such as ammonium sulfate or are ground from minerals like limestone. They're rated by percentages of nitrogen (N), phosphorus (P), and potassium (K). All commercial tomato fertilizers are high in phosphorus, such as 5-10-5, which is five percent nitrogen, ten percent phosphorus, and five percent potash.

Miracle Grow Box

Some gardeners use both organics and inorganics at different stages. I use 5-10-5 inorganic fertilizer in a weak water solution for feeding seedlings once per week when growing tomatoes from seed in a non-fertilized soil mix. But I also use organic mulch and compost to enrich the health and quality of my garden soil for tomatoes.

How to apply tomato fertilizer

When first transplanting into the soil

A note of caution

Whenever using commercial fertilizer, you'll want to carefully read the label. Overfeeding or incorrect application can be worse than no fertilizer. Also, excess runoff is harmful to waterways.

  1. Prefertilize the soil a few days prior to planting. Mix organics such as manure or compost, or a commercial 5-10-5 tomato fertilizer thoroughly into the soil .
  2. After planting, water your transplants with one of the many tomato starter solutions which are high in phosphorous. You can make your own starter solution by mixing 2 tablespoons of 5-10-5 dry tomato fertilizer into each gallon of water. Pour about a pint of solution on each new transplant.
  3. Wait to fertilize again until after the first tomato fruits appear.

After the first tomatoes reach golf ball size

  1. Begin a regular fertilization program of once or twice per month for the remainder of the growing season.
  2. Use one of the following methods:
    • Feed plants with a liquid fertilizer using a watering can or hose feeder. Use commercial 5-10-5 tomato fertilizer or make a solution of manure tea (which is made by soaking composted manure in water, see directions on the bag).
    • Or, mix dry 5-10-5 fertilizer into the soil around each plant six inches away from the stem following the manufacturer's directions.

When growing tomatoes in containers

  1. If you are using a pre-fertilized soil mix no additional tomato fertilizer is necessary for the first few weeks.
  2. Begin a regular feeding program of twice per month applications of liquid fertilzer as described above.

Time-Release Tomato Fertilizer

Jobe's Fertilizer Spikes
  1. An alternative, easy method for fertilizing tomatoes, controlled-release fertilizer slowly releases nutrients for an extended period.
  2. Follow the manufacturers directions.
  3. One type uses spikes, two per plant which are pushed one-inch into the soil 6- to 8-inches from the plant on opposite sides. This type lasts for eight weeks. An advantage of spikes is they can't be washed away like surface applied fertilizers.

Signs of Nutrient Deficiency in Tomatoes

Nitrogen deficiency:

  • Small or light green leaves
  • Very slow growth and stunted stems
  • Flower buds dropping off
  • Correct by applying a fertilizer high in nitrogen, such as blood meal

Phosphorus deficiency:

  • Foliage turning purple
  • Small leaves
  • Late fruiting
  • Correct by applying a fertilizer high in phosphorus, like bone meal

Potassium deficiency:

  • Slow, stunted growth
  • Fruits ripening unevenly
  • Dying leaves
  • Correct by adding potassium-rich fertilizer such as potash or by mulching with organic material

Boron deficiency:

  • Black areas at growing point of stem
  • Stunted stems
  • Abnormally bushy plant
  • Correct by fertilizing with manure

Calcium deficiency:

  • Upper leaves turning yellow
  • Plants appear weak
  • Thick, woody stems with dead areas
  • Correct by spreading crushed eggshells around the plant or applying bone meal

Magnesium deficiency:

  • Brittle, curled-up leaves
  • Fruit lacking in flavor
  • Correct by by mixing dolomite lime or one tablespoon of Epsom salts into the soil


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