Education Materials

Introducing Harrell's EarthMAX

Harrell’s EarthMAX is a unique soil additive designed to promote maximum soil and plant health in turf and ornamental programs.

Understanding Nitrogen

Learn about nitrogen's role as a major nutrient from plant and soil expert Lynn Griffith!

Spider Mites

Spider mites come in a variety of shapes and sizes, but they all have one thing in common: they’re bad news for plants.


Nematodes are unsegmented roundworms that live just about everywhere on Earth, but some varieties can cause problems for growers and turf managers.

Plant Physiology for Growers, Part 1: How Plants "Think"

Plants aren't able to think the way we are, but that doesn't mean they're helpless.

Diagnosing Foliar Nutrient Deficiencies

This course covers common nutrient deficiencies in plants.

The Use of Coir in Potting Media

Learn about coir as a media component in potting mixes

Water Quality and Its Effect on Media

Learn about water quality and how it impacts plants and soil.

Introducing Harrell's MAX Cal Plus

Phosphorus – A Horticulture Perspective

In this learning course, Lynn Griffith discusses the primary nutrient Phosphorus and how it relates to horticulture.

Soil & Plant Tissue Testing

Learn Techniques for Taking Soil & Tissue Samples for Testing!

Rain Water vs. Irrigation Water

Ever noticed that plants respond better to rain water than to irrigation water?

EC Does it: Understanding Soluble Salts

This course describes how soluble salts impact fertilizers and plants.