I have English ivy (or common ivy) in my garden. I’ve never fertilized the soil around the plant because it grows very well without the addition of chemicals. I’ve read that the plant often needs very little or no fertilizer, assuming it’s growing in soil containing organic matter. If fertilizer is required, garden experts recommend that it includes a balanced ratio of chemicals.
Specific number sequences show the amount of nitrogen, phosphorus, and potassium in a bag of fertilizer. For example; a 15-15-15 bag contains 15% nitrogen, 15% phosphorus, and 15% potassium. This is a ratio that is often recommended for English ivy, though I have no experience in using it myself. It’s important to follow the instructions on the fertilizer bag carefully, and to avoid sprinkling the fertilizer on the leaves of the plant.