Herbaceous Perennial Nutrition: What You Need to Know

Phosphorus Deficiency on Gaillardia
Figure 1. Phosphorus (P) deficiency on lower leaves of blanketflower (Gaillardia aristata ‘Arizona Sunset’).

Managing containerized herbaceous perennial nutrition and understanding the crops’ needs can be difficult if the proper tools are not available in a grower’s tool kit. The difficulty of managing nutrition of herbaceous perennials is often the diversity and fertility requirements among perennial species, growing season, and the production facilities, such as greenhouses, shade houses, or outdoor container nurseries. To help you keep your plants healthy and productive, this article will discuss the basics of managing, monitoring, and understanding containerized herbaceous perennial nutrition.

Fertility

Nutrients are provided to containerized herbaceous perennials in a variety of methods, such as water-soluble feed (fertigation), or by incorporating or top-dressing the substrate with controlled- or slow-release fertilizers. Irrespective of how nutrients are supplied, plants require primary [nitrogen (N), phosphorus (P), and potassium (K)] and secondary [calcium (Ca), magnesium (Mg), and sulfur (S)] macronutrients to develop and grow, though these nutrients are often depleted in the substrate and need to be frequently replenished.

To replenish these nutrients, growers can select from a wide range of commercially available fertilizers. When selecting a fertilizer, consider the form of N being applied, whether it is ammonium, nitrate, or urea, because plants respond to each N form differently. For example, plants fertilized with high concentrations of ammoniacal- or urea-N often display soft, lush growth because of rapid leaf expansion and internode elongation. Furthermore, flower and root development are diminished.

In contrast, plants fertilized with high concentrations of nitrate-N tend to be toned or compact without any negative effects on flower or root development.

So which fertilizer is best for you? There is no right or wrong answer, but growers should consider the following when selecting a fertilizer:
• N form
• Solubility
• Acidic or basic properties
• Release time or longevity (controlled- or slow-release fertilizers)
• Handling procedures
• Experience
• Price

Nitrogen Deficiency on Foxglove
Figure 2. Nitrogen (N) deficiency on lower leaves of foxglove (Digitalis purpurea ‘Camelot Lavender’).

Growers should also consider the plant response to the fertilizer being applied. As mentioned before, this can be influenced by the N form, but also by P, which can control plant height when limited. Limiting or providing excessive nutrients may result in deficient (Figure 1) or toxic symptoms, respectively. For instance, growers who provide 50 ppm N may observe chlorotic plants (Figure 2), while at 700 ppm N, plants may display toxicity symptoms. Typically, 100 to 300 ppm N is adequate for proper plant growth, but may vary by species.

Furthermore, not all fertilizers are the same, and a complete fertilizer may not supply all the nutrients in adequate amounts for plant growth. For example, not all water-soluble fertilizers contain large amounts of Ca and Mg.

Growers often rotate between acidic fertilizers that contain little Ca and Mg and basic nitrate-N fertilizers that contain Ca, but limited Mg. Therefore, growers can supplement Mg by applying Epsom salts monthly at the rate of 1 pound per 100 gallons of water. Calcium and Mg are also available to plants from calcitic or dolomitic limestone used to adjust substrate pH or from the irrigation water, though these nutrients are typically available in small amounts and growers should not depend upon these sources to provide plants with adequate Ca and Mg.

Substrate

Containerized herbaceous perennials are grown in substrates composed mostly of either peat, coir, or composted softwood bark, or a combination of these components. The pH of these components in combination with the moisture content of the substrate determines the pH. For example, the pH of peat may range from 3.0 to 4.0, while coir may range from a pH of 4.9 to 6.8. Therefore, it is important to determine initial substrate pH prior to transplant, regardless of if you purchase pre-mixed or blend your own substrate.

Initial substrate pH can be determined by conducting either the saturated media extraction (SME) or 2:1 (substrate:distilled water) extraction methods. Determining the initial substrate pH will allow growers to adjust pH by amending substrates with limestone to achieve an optimal pH of 5.6 to 6.2 for containerized perennials. The optimal pH may be species-specific.

What influences pH throughout production? Substrate pH is influenced by:
• Substrate amended with limestone
• Fertilizer properties
• Irrigation water alkalinity
• Plant roots

Substrate pH defines how available nutrients are to plants. In general, macronutrients are less likely to be influenced by substrate pH; however, for micronutrients this is a different story. Substrate pH influences the availability of micronutrients, for example, iron (Fe) and manganese (Mn).

Chlorosis in Garden Mums
Figure 3. Young developing leaves of garden mum (Chrysanthemum sp.) exhibit interveinal chlorosis (yellowing) because of high pH induced iron (Fe) deficiency.

High substrate pH limits mobility of Fe to young developing leaves, thus resulting in Fe deficiency or interveinal chlorosis (yellowing) (Figure 3). While at low substrate pH, Fe and Mn accumulate in the older (lower) leaves and may result in Fe/Mn toxicity. To produce healthy and marketable plants, growers should monitor the pH using Pour-Thru or SME methods to ensure pH has not fallen or risen above the optimal range.

Water

Contrary to belief, substrate pH is primarily influenced by the irrigation water alkalinity level and not the pH. Irrigation water alkalinity (i.e., dissolved carbonates such as calcium carbonate [CaCO3] and bicarbonates {calcium [Ca(HCO3)2], magnesium [Mg(HCO3)2], and sodium [NaHCO3] bicarbonates}) is the major regulator that influences pH rise in substrates. Irrigation water containing high alkalinity levels will increase the substrate pH, thus inducing chlorosis of the upper leaves. Hence, growers should monitor irrigation water alkalinity by submitting water samples for lab analysis or conduct in-house alkalinity testing (Figure 4).

Determining and monitoring the irrigation water alkalinity will allow growers to make informed decisions such as acidifying or neutralizing the irrigation water to reduce alkalinity. Generally, growers should maintain an alkalinity of 80 to 120 ppm CaCO3 for containerized herbaceous perennials. The most common acid used to neutralize irrigation water is sulfuric, but nitric and phosphoric acids are often used.

In House Testing Of Irrigation Water
Figure 4. In-house testing of irrigation water will help you determine alkalinity.

How much acid do you need to neutralize irrigation water alkalinity? The collaborative group of floriculture specialists called e-GRO established AlkCalc, an interactive calculator, which assists growers in making corrective decisions. AlkCalc calculates the amount of acid needed to add to irrigation water to modify the pH and alkalinity levels. Of course, growers need to know their current irrigation water pH and alkalinity levels, and which acid they plan to use.

Managing, monitoring, and understanding nutrition of containerized herbaceous perennials does not need to be a daunting task. Understanding basic plant needs and nutrition will allow you to choose the right fertilizer(s) for your operation. Additionally, monitoring substrate pH and irrigation water alkalinity will allow you to establish the tools to manage and grow healthy containerized herbaceous perennial crops. For more information on perennial nutrition, refer to Perennial Solutions: A Grower’s Guide to Perennial Production, by Paul Pilony.

Topics: , ,

Leave a Reply

More From Fertilization...
Acid Injection for Irrigation feature

October 23, 2017

How to Balance Plant Nutrition and pH in Ornamentals

If you want to maintain healthy plants, understanding the relationship between plant nutrition and pH is a good place to start.

Read More
NatureFresh Chili Dog

October 17, 2017

NatureFresh Farms Uses Pest-Detecting Dog to Sniff out Pepper Weevil

Knowing that many worker dogs are trained to recognize and discover scents associated with drugs or bombs, the company figured it was possible to train a dog to recognize pepper weevil.

Read More
Botrytis Symptoms on Leaves

October 17, 2017

How One Grower is Battling Botrytis with a New Biological

CropKing in Lodi, OH, recently began using a new beneficial fungus in its fight against Botrytis in its greenhouse tomatoes. So far, the results have been promising.

Read More
Latest Stories
Acid Injection for Irrigation feature

October 23, 2017

How to Balance Plant Nutrition and pH in Ornamentals

If you want to maintain healthy plants, understanding the relationship between plant nutrition and pH is a good place to start.

Read More
Nitrogen Deficiency on Foxglove feature

October 7, 2017

Herbaceous Perennial Nutrition: What You Need to Know

Regardless of your production challenges, keeping containerized herbaceous perennials healthy is as simple as understanding the basics of their nutritional needs.

Read More
Proven Winners Potting Soil and Plant Food

September 15, 2017

Sun Gro Forms New Distribution Agreement with Proven Wi…

Sun Gro will distribute Proven Winners-branded potting soils and plant foods to independent garden centers.

Read More
Magnesium deficiency on poinsettia

July 4, 2017

How to Manage the 3 M’s of Poinsettias: Manganese, Mol…

Proper nutrition is a critical part of successful greenhouse production. Managing these three key elements properly will keep your poinsettia crops healthy and strong.

Read More
Paul Fisher Fertilizer feature

June 12, 2017

How to Improve Customer Success by Adding Residual Fert…

Even if it costs a few cents more per pot or extra labor, your customers will thank you with repeat sales.

Read More
Greenhouse Plant Nutrition

May 26, 2017

University of Florida Course Helps You Improve Greenhou…

The University of Florida (UF) Institute of Food and Agricultural Sciences is offering an Advanced Nutrient Management course through its online greenhouse training program.

Read More
cannabis-nutrients

October 21, 2016

How To Select The Best Nutrients For Growing Cannabis

With a little bit of knowledge about the requirements of cannabis plants and how they absorb and utilize nutrients, you can confidently select the products you need without breaking the bank.

Read More
dramm-ferticart-feature

September 19, 2016

New Fertilizer Injector Cart Provides Full Aeration And…

The new 50-gallon Ferticart from Dramm is designed to keep chemicals such as fungicides and plant growth regulators — as well as nematodes — viable through constant recirculation.

Read More
Roots with plant media background XL-W

July 2, 2016

University Of Florida Offering Online Nutrient Manageme…

Topics include common nutrient problems, essential nutrients, fertilizer types, how to interpret a fertilizer label, managing total nutrient level, pH, and EC, onsite testing, and growing media.

Read More
Agro-K

May 19, 2016

Agro-K Expands Distribution In New England Through Part…

Agro-K, which manufactures conventional and organic foliar plant nutrients, will distribute its full line of foliar fertilizers and soil biological products through NEAG.

Read More
Fertilizer Rates Feature Image

January 29, 2016

Bioworks Releases New Higher Nitrogen Fertilizer For Or…

Verdanta N-Vita 9-4-3 promotes foliar growth and features a slow release process, making nutrients available for a longer period of time.

Read More
Primrose Downward Leaf Roll From Calcium Deficiency

January 11, 2016

How Calcium Plays A Critical Role In Plant Health

Supply vegetables and poinsettias with a healthy amount of calcium to avoid tip and leaf burn.

Read More
Sustane Research Greenhouse 2015

January 7, 2016

Fertilizer Manufacturers Aim To Deliver Sustainable Sol…

Industry experts discuss the latest trends to help ensure 2016 is your best year yet.

Read More
Fertilizer Rates Feature Image

August 12, 2015

Selecting Fertilizer Rates For Several Spring Bedding P…

Fertilizing bedding plants can be difficult due to the differing needs of the large variety of plants that we grow. Many operations do not grow enough of any one crop to cater the fertilizer specifically for each crop. Therefore, grouping crops with similar fertilizer requirements and having two to three fertilizer strengths available is a practical way to ensure plants are getting the fertilizer they need. With many new plant varieties on the market, we wanted to conduct a trial at Cornell University to determine best fertilizer rates for several common bedding plant crops. 22 Bedding Plants Studied To Establish Fertilizer Rates Plugs and rooted liners of 22 crops (Table 1) were transplanted into 4-inch (500 mL volume) round pots with a commercial peat/perlite based substrate. The plants were grown in a glass greenhouse at Cornell University during the spring season at a spacing of one plant per square foot. Heating set […]

Read More
NSOrganicPlantFood3-1-1_featured

June 13, 2015

UMASS Fertilizer Trials Recommend Nature’s Source Organ…

In a recent online fact-sheet at its Extension website, the UMass Amherst Center for Agriculture, Food and the Environment lists Nature’s Source Organic Plant Food 3-1-1 as “the best liquid organic fertilizer,” according to Dr. Douglas Cox, Stockbridge School of Agriculture. It is called-out by the Extension after a number of years of studying the use of organic fertilizers for growing commercial greenhouse crops. The trials evaluated traditional water soluble and granular slow-release chemical fertilizers. Dr. Cox recommends Nature’s Source Organic Plant Food 3-1-1 as a liquid fertilizer that is readily available, cost effective, OMRI-listed and with good label directions for greenhouses. He also mentions the ease-of-use in how it mixes well with water and can pass fertilizer injectors. “Nature’s Source is currently the best liquid organic fertilizer,” Cox wrote in his article “Organic Fertilizers – Thoughts on Using Liquid Organic Fertilizers for Greenhouse Plants,” “I have seen no foliar chlorosis yet with this fertilizer. Nature’s source is widely available and a great […]

Read More

January 9, 2015

6 New Fertilizer Products For Healthy Plants

These five products add even more options for delivering nutrients to the root zone.

Read More

January 7, 2015

Fertilizers And The Future

As growers look for new ways to cut costs and conserve resources, fertilizer and equipment companies are offering products that strive to save water, reduce toxic runoff and keep chemicals out of the equation.

Read More

December 31, 2014

Gain Greater Control Of Fertilizer With Automated Ferti…

University researchers look at integrating irrigation and fertilization with the help of water sensors to reduce fertilizer treatments and improve application timing.

Read More