Water-soluble crystalline formulations like ammonium sulfate dissolve almost instantly with irrigation. With 2 irrigation cycles of 15 minutes each you can typically expect most any granular fertilizer to be dissolved into the lawn as a general rule of thumb.

Does granular fertilizer dissolve?

You can dissolve granular fertilizer in water though it will take about 24 hours or more to completely dissolve. You can use the solution as a liquid fertilizer for quickly providing essential nutrients to your container plants.

What if it rains after I fertilize my lawn?

Heavy rain right after fertilizing, however, may make the fertilizer run off the soil or into the lower layers, where it won’t do as much good for your roots. Using fertilizer on wet grass the day after heavy rain is also not ideal, because the fertilizers can stick to wet grass and damage it.