In a backyard where you're always cleaning up fallen leaves and lawn clippings instead of leaving them in place to break down and release nutrients back into the soil, the nutrient levels of your soil can become depleted over time. This can cause your trees to languish if you don't fertilize them from time to time. Fertilizing your trees can make the leaves more vibrant, encourage healthier flowering (on trees that flower), and help the trees fight off fungal diseases. But only if you fertilize the right way. Here's how.

Spread the fertilizer out.

One of the biggest mistakes homeowners make when fertilizing a tree is dumping all the fertilizer right by the trunk. The tree's roots spread out around the trunk. The soil surrounding them is the soil you need to nourish! Usually, a tree's root system stretches about as far out as the tree is tall. So if you have a 20-foot tree, its root system probably has a radius of around 20 feet. Scatter the fertilizer in a circle this wide. (There's no need to be measure here -- just make sure your circle is about as wide as the tree is tall.)

Fertilize while the tree is dormant.

There's a right time and a wrong time to fertilize a tree. The tree needs the fertilizer the most in the early spring when it's just preparing to add new growth. Try to apply the fertilizer in March before the buds appear. (If you live in a colder climate, you may be able to fertilize in April.) If you apply the fertilizer later than this, the tree may use the nutrients to produce only leaves, and not new branches, which is not ideal.

Select a tree-specific fertilizer.

Different fertilizers have different ratios of nutrients. Make sure you select one that's made specifically for trees. A general-purpose fertilizer is also acceptable as these generally contain balanced amounts of each nutrient. Just avoid fertilizers made for tomatoes or flowers, as these tend to be too high in nitrogen and may encourage too much leaf growth.

Water it in well.

Try to apply the fertilizer before rain comes so that the rain can wash it down into the soil. If there's no rain in the forecast, water the soil around your tree for an hour or two after you fertilize. Otherwise, the fertilizer will stay too close to the surface where the roots can't access it. Click here to learn more about dormant fertilization.