Fertilizer For Grapefruits

Fertilizer for Young Trees

• Young grapefruit trees do not need much fertilizer. For a new tree, divide one cup of ammonium sulfate fertilizer into three applications. Every four months, scatter a portion of the fertilizer around the grapefruit tree and water it so the fertilizer can dissolve and reach the tree's roots.

Fertilizer for Maturing Trees

• As your grapefruit tree matures, it will need more fertilizer each year. For each year the tree ages, add one cup of ammonium sulfate fertilizer. For example, a two-year-old tree will need two cups of ammonium sulfate for the entire year; a three-year-old tree will need three cups. Divide the fertilizer into three applications just as you would with a new tree. Apply the fertilizer evenly several times a year.

Fertilizer Timing

• Ideal timing for application of fertilizer to grapefruit trees is in February, May and September. For spring applications, apply when the tree is in bloom to make sure the tree has enough nutrients to produce fruit. Applying small amounts multiple times each year also prevents nitrates from entering the groundwater supply.

Considerations

• An easy way to know your grapefruit tree is receiving proper nutrition is to purchase a fertilizer specifically designed for citrus fruits and apply it according to the label. Many growers believe that the more fertilizer you use, the better your fruits will grow. The reality is that over-fertilizing, especially if you use too much nitrogen, can cause problems for grapefruits. Bumpy skins, misshapen fruits and burned leaves can result. If you notice any of these symptoms in your grapefruit trees, make sure you are not using a fertilizer with a high rate of nitrogen, or overapplying fertilizer.