Improving Rewetting

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 out through channels or flows off the media surface because of poor rewetting, customers are unlikely to water thoroughly. The choice of media components or the use of a wetting agent can improve rewetting. 

Understanding Rewetting Characteristics

Rewetting ability refers to how rapidly a root medium absorbs water, and thus reaches its potential for maximum available water-holding capacity, with minimal leaching. Unfortunately, many of the components used to make container media do not absorb water easily. For example, organic materials such as peat or bark tend to be hydrophobic and may be difficult to rewet if allowed to become too dry.

Researchers have shown that when the water content (by volume) of pine bark was allowed to decrease below 35 percent, little of the water applied in a single irrigation was retained. As moisture levels increased to 50 percent, the bark became progressively more efficient at retaining the applied water.

The state of decomposition of the peat or bark may also affect the ability to rewet after drying. Older, more degraded peats contain relatively high amounts of humic acid. Humic acid plays an important role in the lime requirement and the cation exchange capacity of peat. However, if degraded peats are allowed to become excessively dry, the humic acid may form hard granules that have lost their initial capacity to absorb water, making them more difficult to rewet.

Amendments such as vermiculite, rockwool, sand or calcined clay can be added to a root medium to increase rewetting. These materials improve rewetting ability because they absorb or distribute water independent of their moisture content prior to water being applied. Water can therefore be absorbed and distributed by the root medium even when the peat or bark is dry. When using amendments like vermiculite or calcined clay to help with rewetting, it is important to add them into the medium at a high enough percentage to influence water absorption (often 30 percent or more by volume). 

Wetting Agents

Much of the research to improve rewetting ability of peat has evaluated wetting agents (also termed surfactants). Many surfactants exist but many are phytotoxic to plants. Wetting agents used in horticulture are nonionic materials that bind to the surface of the root media particle and decrease the surface tension of the water, thus increasing the penetration of water into the root media. Because of the hydrophobic nature of peat and bark, wetting agents are commonly added to root media at mixing to aid in rewetting. 

The useful life of a wetting agent depends on factors such as media storage duration and temperature before planting, media components, watering practices and wetting agent rate and type. For example, impatiens were grown in 10-inch baskets using 18 commercial media, each containing a wetting agent added at mixing. After six months, AquaGro wetting agent was reapplied as a drench to half the baskets from each media.

The reapplication of the wetting agent had no effect on available water-holding capacity in the media containing long-fibered grower-grade peat. However, in media containing more degraded peats, the reapplication of a wetting agent increased available water-holding capacity by as much as 50 percent compared to the same media without the wetting agent drench.

Reapplication of a wetting agent is necessary if you notice that considerable leaching is needed before the medium is moist through the entire profile. About 10 minutes after an irrigation, pull off the pot and check whether the entire root zone is moist. Patchy drying of media can sometimes indicate poor rewetting. You can also measure rewetting directly.

Rewetting ability, available water-holding capacity and water release characteristics determine whether your customer is able to keep a plant alive during the summer, and whether you will have a repeat sale next year. Next month, we will turn our focus to fertilization for success with baskets.

Leave a Reply

One comment on “Improving Rewetting

Latest Stories
Petal It Forward 2017

October 17, 2017

Petal It Forward Event a Hit for Both Industry Members …

Check out how this year’s Petal It Forward event brought smiling faces to people across the country, including one personal story.

Read More

October 17, 2017

14 New Shrubs With Fringe Benefits

What’s popular with shrubs? Consumers want varieties that will give them more return on their investment, in terms of long-lasting blooms and multi-season appeal that lasts from spring until fall and at times stretches into the winter months. Here are 14 new varieties of shrubs and sub-shrubs to consider for your product mix in 2018.

Read More
NatureFresh Chili Dog

October 17, 2017

NatureFresh Farms Uses Pest-Detecting Dog to Sniff out …

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
Researchers Study Rose Varieties

October 17, 2017

Rose Rosette Update: Research into Detection and Manage…

Halfway through a five-year, $4.6 million grant to combat rose rosette disease in the U.S., a national research team is encouraged by the amount of information learned, but admits having a way to go before finding how to overcome the deadly problem.

Read More
Seville Production Line

October 17, 2017

Production Technology Conference Tour Attendees See Tec…

AmericanHort’s Production Technology Conference in Dallas, TX, kicked off on Monday, Oct. 10, with a tour of three local production facilities.

Read More
Botrytis Symptoms on Leaves

October 17, 2017

How One Grower is Battling Botrytis with a New Biologic…

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
TTA PackPlanter S-2

October 16, 2017

TTA Introduces New Transplanter Suited for Smaller Grow…

The PackPlanter S has 16 grippers and a capacity of 10,000 to 20,000 plugs per hour in a small frame.

Read More
Karen Reardon, RISE

October 15, 2017

Karen Reardon of RISE Honored by CropLife America

CropLife America presented Reardon with its highest staff award for her successful effort to defend against the ban of pesticide use on private property in Maryland.

Read More

October 14, 2017

PlantPeddler Hosting Poinsettia Variety Day in December

The event will feature side-by-side comparisons of more than 100 commercial and pre-released varieties from seven breeders.

Read More
Whitefly adult

October 13, 2017

Researchers Continue to Keep Close Tabs on Whitefly

Dr. Lance Osborne of the University of Florida and Dr. Cindy McKenzie of USDA’s Agricultural Research Service are evaluating insecticide efficacy and the impact of product rotations on whitefly biotype populations.

Read More
GVZ Glasshouses

October 12, 2017

How to Deal With Common Greenhouse Maintenance Issues

The most common problems often come from a lack of cleanliness and faulty equipment. Here are a number of tips you can follow in each of these areas.

Read More
Mark Schneid

October 11, 2017

Bayer’s New Head of Environmental Science Has Roots in …

Mark Schneid says one of the biggest challenges the industry faces is the constantly evolving customer — particularly among millennials.

Read More
TreetownUSA

October 10, 2017

Houston-Based TreeTown USA Acquires Village Nurseries

With the addition of the new West Coast division, which will continue to operate under its trade name of Village Nurseries, TreeTown USA will now encompass 16 farm locations throughout California, Texas, and Florida, with more than 4,000 acres in production.

Read More

October 10, 2017

Sharpen Your Skills in Cost Management and Profitabilit…

The University of Florida is offering a new online course on costing and profitability. The course will take growers through the process of how to accurately evaluate cost of production, labor efficiency, pricing, and equipment investment decisions.

Read More

October 10, 2017

Coastal Callas Is a Dream Fulfilled for Founder Adrian …

Adrian Espinoza and his family founded Rancho Espinoza Inc. and Coastal Callas in California seven years ago with a mission and purpose to provide consistent quality and reliable supply of calla lilies to the marketplace.

Read More
Phillips, Ball Seed Partnership

October 10, 2017

Philips Lighting, Ball Seed Partner on Distribution

Ball Seed will now offer Philips GreenPower LED lighting as a complement to its liners, plugs, unrooted cuttings, seed, and prefinished products.

Read More
1B Filling trays for Transplanting Feature

October 9, 2017

Maximize Your Labor Efficiency When Sticking Plant Cut…

Transplanting unrooted cuttings into trays is one of the most labor-intensive activities in greenhouse production.

Read More
AgriNomix

October 8, 2017

Greenhouse Equipment Supplier AgriNomix is Expanding

In an effort to keep up with demand from growers venturing into automation, the company is adding almost 20,000 square feet of warehouses and offices.

Read More