Has Your Container Run Out of Fertilizer? Time to Recharge with Osmocote.

By early August, a container full of tired-looking annuals usually isn’t thirsty — it’s hungry.

You start noticing something strange this time of year. The petunias are still alive. The SunPatiens are still growing. Everything is getting watered on schedule… but the flowers just aren’t as impressive as they were in June.

Often the problem isn’t water. It’s food.

If you mixed a controlled-release fertilizer like Osmocote into your containers this spring, there’s a good chance those granules have done exactly what they were designed to do — slowly released most of their nutrients over the past several months. Giving pots a late-season boost is one of the simplest ways to keep them beautiful into September.

Controlled-release fertilizers work differently than the water-soluble kind. Each granule is wrapped in a polymer coating that lets nutrients move into the soil as temperatures warm and moisture passes through the pot. The warmer the weather, the faster they release — so a hanging basket watered every day through a hot Indiana summer often exhausts its supply much sooner than gardeners realize.

A few things speed the burn:

• ✓ High temperatures
• ✓ Frequent watering
• ✓ Smaller containers that heat up quickly
• ✓ Fast-growing annuals with high nutrient demand

Your plants don’t have to turn yellow to need feeding. Watch for:

• ✓ Flower production slowing dramatically
• ✓ New growth coming in noticeably smaller
• ✓ Leaves losing their rich green color
• ✓ Plants that look healthy but have simply stopped growing

If more water hasn’t solved it, fertilizer is usually the missing piece.

It takes only a few minutes:

• ✓ Sprinkle a light application of Osmocote evenly across the soil surface
• ✓ Lightly work the granules into the top inch of mix
• ✓ Water thoroughly

Within a couple of weeks, most annuals respond with darker foliage, stronger growth, and another flush of blooms.

• ✓ Petunias and calibrachoa
• ✓ SunPatiens
• ✓ Angelonia
• ✓ Lantana
• ✓ Hibiscus
• ✓ Mixed patio containers

All of these still have weeks — sometimes months — of beautiful growing weather ahead.

One of the biggest misconceptions I hear is that a plant is “done for the year” because it isn’t blooming like it did in June. In reality, it’s often just hungry. A fresh application of Osmocote, combined with a little pruning and consistent watering, can completely transform a container and carry it right into fall.

Reference: Purdue University Extension · Schlegel Greenhouse production notes