TFTC #44 Spring Tree Care

As winter fades and your landscape begins to wake up, it’s the perfect time to give your trees a boost. Spring fertilization is one of the best things you can do to ensure healthy, vigorous growth through the season—and long-term resilience year after year.

During spring, trees begin to grow more rapidly, drawing nutrients up into the canopy to prepare for the summer growing season. A greener canopy and healthy stems help trees perform critical functions: producing oxygen and cooling the environment through transpiration.

It's important to remember that fertilizer isn’t "food" for trees—it's a source of essential nutrients they need to do their job effectively. Trees begin absorbing these nutrients when soil temperatures reach about 60°F, so timing matters.

But not all trees (or soils) are the same. Here’s what you need to know to fertilize smart this spring.

Trees spend the winter in dormancy, conserving energy and slowing their growth. As temperatures rise and sap begins to flow, trees need nutrients to support:

• New lead and shoot growth
• Root expansion
• Recovery from winter stress
• Resistance to pests and diseases

Spring fertilization helps jumpstart this process by replenishing vital nutrients in the soil.

Tree fertilizers typically contain three main nutrients:

• Nitrogen (N) – for lush, green growth and foliage development
• Phosphorus (P) – supports root development and flower/fruit production.
• Potassium (K) – enhances overall vigor and disease resistance.

In most cases, trees benefit most from a slow-release, nitrogen-rich fertilizer in spring.

Here are a few options to consider:

If your tree is in a mulched area, opt for a slow-release granular organic fertilizer that contains Mycorrhiza. These beneficial fungi form a symbiotic relationship with the tree’s roots, improving nutrient absorption over time.

• Easy to apply around the drip line.
• Releases nutrients over weeks/months.
• Ideal for ornamental and shade trees.

When trees are planted in grass, turf roots often outcompete tree roots for nutrients. In this case, we recommend:

Direct Trunk Injection:
A small amount of concentrated chemical fertilizer is injected directly into the tree’s xylem cells (located just beneath the bark), ensuring efficient nutrient delivery to the canopy. Think of it as an IV for your tree.

• Fast-acting for immediate uptake.
• Great for younger or stressed trees.
• May require more frequent application.

Deep Root Soil Injection:
A probe is inserted 6–8 inches into the soil to inject liquid fertilizer in a grid pattern from the trunk to the tree’s drip line. This method bypasses competing grass roots and is best handled by professionals due to the specialized equipment involved.

• Uses pressurized injection to deliver ferilizer directly to the root zone.
• Ideal for urban trees in compacted soils or poor enviornments.
• Requires professional equipment and expertise.

• Timing: Early to mid-spring (March–May depending on region) is ideal.
• Avoid fertilizing too late in the season—late summer or fall fertilization can trigger soft, frost-sensitive growth.

Be sure to check out our full line of plant health care chemicals and fertilizers to help get your trees ready this spring. https://sherrilltree.com/phc/chemicals/