Author Archives: Bill Argo

About Bill Argo

Bill Argo is technical manager of Blackmore Co. You can eMail him at

Understanding Plant Nutrition: Correcting Low Media pH

Iron/manganese toxicity is a common problem when media-pH drops below the ideal level in certain crops, including geraniums, marigolds, lisianthus, and pentas. As media-pH decreases (meaning the pH becomes more acidic), iron and manganese become more soluble, resulting in higher concentrations in the soil solution. For each drop in media-pH by one unit, for example

Understanding Plant Nutrition: The Series

Understanding Plant Nutrition: An Introduction Read about the basics on essential nutrients for plant growth, uptake of nutrients and pH’s effect on nutrient solubility. Nutrient Sources: Media Cation Exchange Capacity The authors take a look at the myth that cation exchange capacity is important to soilless media. Limestone and pH Why does limestone need to

Understanding Plant Nutrition: Managing Media EC

High fertilizer levels can be too much of a good thing, leading to excess growth, nutrient toxicity and potential runoff of nutrients into the environment. Conversely, low fertilizer levels can lead to nutrient deficiency symptoms. A basic goal for a nutrition program is to supply nutrients to the crop within an acceptable range for healthy

Understanding Plant Nutrition: Managing Media pH

Managing the pH of container media is a challenge in the greenhouse and nursery industry. Many growers face problems associated with their media pH either drifting up or down to levels that result in loss of crop quality and sales. In this article, we will discuss how the factors that we have discussed in previous

Understanding Plant Nutrition: Controlled- And Slow-Release Fertilizers

Using controlled-release (CRF) and slow-release (SRF) fertilizers allows growers to supply nutrients for an extended duration without the specialized equipment needed to apply water-soluble fertilizers. These fertilizers are added to the media at mixing or applied to the media surface after planting. Nutrient runoff can be reduced using CRF and SRF, especially compared to applying

Understanding Plant Nutrition: Fertilizers And Micronutrients

Micronutrient (iron, manganese, zinc, copper, boron and molybdenum) nutrition is different from managing macronutrients, such as nitrogen, in three fundamental ways. First, the solubility and plant availability of micronutrients is affected by media pH to a much greater extent than is macronutrient solubility. Second, the difference between acceptable concentrations of micronutrients and concentrations that are

Understanding Plant Nutrition: Fertilizers And Macronutrients

When you select a water-soluble fertilizer, the primary goal should be to supply plants with a sufficient amount of essential plant nutrients for good growth and flowering. In this article, we will focus on macronutrients (nitrogen, phosphorus, potassium, calcium, magnesium and sulfur) supplied by water-soluble fertilizers. We will discuss macronutrient sources, fertilizer formulations and the

Understanding Plant Nutrition: Fertilizers And Media pH

Choosing fertilizers can be one of the most important decisions you can make for managing the media pH of container grown crops. It is therefore important to understand how fertilizers raise or lower media pH, which results largely from the form of fertilizer nitrogen (ammoniacal, nitrate or urea). This article will help you understand why

Fertilizing Containers

After water management, fertilization is the next most common problem with keeping large containerized plants alive through the summer. Most consumers do not fertilize their plants, or if they do, they don’t apply a sufficient amount to maintain the plants at good quality. In this article, we give specific recommendations about fertilizing of 10-inch baskets.

Improving Rewetting

  Once mixed containers or baskets are sold to a customer, their subsequent watering greatly affects the “use by” date of the plant product and overall consumer satisfaction. How easily the medium rewets is a key to your consumer’s success. It may be unrealistic to educate all our customers to become expert irrigators. If water runs