Free Download: The Guide for Growing Strawberries

Strawberries are definitely not an easy crop and CEA technologies can always help us to provide ideal conditions to improve production window, yield per area and fruit quality. Growers are finding out the great benefits of growing strawberries using the help of CEA. This is the reason why now hydroponic greenhouse production of strawberries is growing rapidly across the world. The present guide has the objective to provide specific information about how to grow strawberries in a hydroponic system inside greenhouses.

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The Advantages of CEA in Strawberry Production

Growing hydroponic strawberries

By Karla García

Strawberries (Fragaria × ananassaDuch.) are an important crop grown in the U.S. with a market value of more than $2.2 billion dollars, producing 1.12 million tons of strawberries in 2019. Most production of strawberries in the U.S. is done in open fields. In the U.S., year-round production is achieved by shifting production between regions across California and Florida. Recently U.S. growers are confronting challenges in open field production. In California, where more than 90% of the total strawberry production is done, annual acreage for strawberries is getting lower due to prolonged drought periods in the field; also, dry weather is increasing pests, making it challenging to manage and control diseases (Green, 2014). Another challenge of U.S. production is the emergence of strong competitors in the strawberry market, Mexico and China.

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2017 retail sales of organic fresh produce reach nearly $5 billion

The Organic Produce Network and Nielsen report sales of organic fresh produce items approached $5 billion in 2017, an 8 percent increase from the previous year. Nearly 2 billion pounds of organic produce were sold in grocery stores last year, which is a 10 percent volume increase from 2016.

At U.S. retail stores, sales of organic fresh vegetables were $2.4 billion. Organic fresh fruit sales exceeded $1.6 billion. Sales of nearly $1 billion in organic value-added produce items brought total sales to $4.8 billion in 2017.

In 2017 organic packaged salad was again the leading organic fresh produce item, approaching $1 billion in sales. Packaged salad still accounts for one in five organic dollars.

Topping the sales in organic fruit were berry crops, which saw a 22 percent increase in volume sales. Organic berry sales, which include strawberries, blueberries and blackberries, topped $586 million in 2017.

New online tool enables growers to diagnose strawberry problems

Scientists and IT developers at North Carolina State University are creating an online diagnostic tool that will assist strawberry growers in determining and resolving crop-related issues.

Starting June 30 strawberry growers will have a new online diagnostic tool to help them identify problems they may encounter with their crops. As part of the National Strawberry Sustainability Initiative grant, which is funded by the Walmart Foundation, a group of North Carolina State University scientists and extension IT developers
are creating a web-based interactive diagnostic key for growers. It will have application to both outdoor- and indoor-produced strawberries throughout the United States.

The key will be accessible through users’ computers, tablets and smart phones. It will be available through the North Carolina Cooperative Extension Strawberry Growers Information website.

A holistic approach

Brian Whipker, professor of floriculture–research and extension, who heads up the project, said the key
is based on attributes.

“There are 21 insect pests, 26 diseases, 14 nutritional disorders and 26 physiological disorders in the key,” Whipker said. “It covers the primary sources of problems. The herbicide damage probably won’t have application to greenhouse production, but almost everything else, including the diseases, nutritional disorders, and most of the physiological disorders and insects will apply.
“When users log onto the website there is a filter on the left side of the homepage that is based on four categories (insect, disease, nutritional and disorder) that they can sort by. The term physiological was replaced by the word disorder.”
A user can click on the insect category and receive all 21 insect pests.
“If the users don’t want to search by type then they can choose differentials based on leaf condition that has 12 options or leaf color that has 10 options,” Whipker said. “They can also search by leaf location, which has six options. Fruit conditions have eight options, including size, texture and color. There are also attributes for root and crown problems.”

The strawberry diagnostic tool being developed at North Carolina State University covers 88 different attributes, including nutritional disorders such as boron toxicity (top) and iron deficiency (bottom).
Filters narrow problem identification

Whipker said the key allows users to narrow down the problem identification by using a series of filters.

“If a grower has interveinal chlorosis, the key can filter the problem down to 12 options,” he said. “The grower can add another filter for mature leaves, which narrows the choices down to four options. The key then filters for a combination of interveinal chlorosis and mature leaves.
There are other characteristics that are listed and the grower can read down that list and sort the problem cause from there. There is one thumbnail photo of each problem that the user can choose from.”
There are different headers for each of the four categories. For diseases there are headers for causal agents including the scientific names. The headers for nutritional disorders include Problem (i.e., iron deficiency); Symptoms (with photographs and a listing of similar problems like mimics); Additional Information; Diagnostic Tips; Corrective Measures and Management.
Whipker said once a grower chooses what he thinks is causing the disorder, he can click on the problem and is taken to a fact sheet.
“There are 88 attributes and there is a fact sheet on each one,” he said. “Most of the fact sheets are two pages long. Some of the disease fact sheets are four to six pages. There are also some hyperlinks for other online resource publications that are available.”
Additional crop information

Whipker said the key template that was used for the strawberry diagnostic tool would have application to other crops.

“Diagnostics are my driving force,” he said. “I have invested $20,000 in a system that can induce nutrient disorders. I’d like towork on the nutrient disorders of greens and herbs. Currently there is no diagnostic key available for herbs.”
Whipker has also produced a nutrient disorder guide for tomatoes, “Tomatoes: Troubleshooting Guide to Nutritional Disorders”.
N.C.  State University horticulture professor Brian Whipker has released a book on tomato nutrient disorders that were greenhouse-induced.

“We produced an iPad-based book for the tomato disorders,” he said. “It is also available as a print-on-demand book at

“The tomato disorder publication is more applicable to greenhouse tomatoes than field-grown. All of the tomato nutrient disorders were greenhouse-induced. A field-based system is more forgiving. With a hydroponic or water-production system there is no residual. If a grower forgets to put in boron, the plants are going to show the deficiency symptoms.”

For more: Brian Whipker, North Carolina State
University, Department of Horticultural Science;

A team effort

North Carolina State University team members on the “Strawberry Diagnostics: a Problem Solving Tool” project include:
Hannah Burrack, Department of Entomology
Frank Louws and Barbara Shew, Department of Plant Pathology
Rocco Schiavone, Jeremy Pattison and Brian Whipker, Department of Horticultural Science
Rob Ladd (developer) and Rhonda Conlon, Extension Information Technology

David Kuack is a freelance technical writer in Fort Worth, Texas;

University of Arkansas scientists tour Belgian strawberry research facility

University of Arkansas researchers gear up to look at
better ways to grow strawberries in controlled environment production

Tom Van Delm, coordinator of strawberry research at
Research Centre Hoogstraten (Proefcentrum Hoogstraten) in Belgium, hosted a
tour for University of Arkansas horticulture researchers. The Research Centre
conducts studies on strawberries, tomatoes and peppers. Gerson Van’t Wout, import/export
manager at Hort Americas, joined the tour and filed this report.
Van Delm (left), coordinator of strawberry
research at Research Centre
Hoogstraten, talks
with University of Arkansas horticulture professor
Evans about the strawberry research being
done at the Belgian facility.

Strawberry specifics
The University of Arkansas researchers were at the Research
Centre to look at the various aspects of strawberry production being studied.
Although many of the systems being used to produce strawberries, including the
use of gutters, drip irrigation, fertigation and supplemental lighting are
similar to what American greenhouse vegetable growers are currently using,
Van’t Wout said that there are differences in how the crops are grown. He said
there will be a learning curve for U.S. growers who want to add
greenhouse-grown strawberries to their product mix.

strawberry production systems,
including NFT troughs, are being studied at
Centre Hoogstraten in Belgium.

Belgian strawberry growers who have switched to greenhouse
production have had an easier time controlling environmental factors including
temperature, humidity and light levels. They also are better able to manage
irrigation, pests and diseases. Van’t Wout said most of the Belgian growers who
have not made the switch to greenhouse production are the ones who have been
doing field production for a long time and are comfortable with that method.

Breeding, pest
management, lighting research

Van’t Wout said that Belgian strawberry breeders are not
hybridizing strawberries specifically for greenhouse production. When a new
variety is introduced by the breeders, he said researchers and growers will try
to produce it in various controlled environment and outdoor growing situations.
Van’t Wout said U.S. greenhouse growers should be able to adapt Belgian-bred strawberries
to their production systems.

The biggest pest problems facing Belgian strawberry
growers are thrips and spider mites. Several trials are being conducted at the
Research Centre with natural enemies, including predatory mites, to determine
their effectiveness on controlling these pests.

Research has also been done with replacing incandescent
light bulbs with LEDs, including Philips GreenPower LED flowering lamp. Van
Delm said that strawberry trials have shown that deep red/white/far red LEDs
are “an effective and energy-efficient replacement” for incandescent bulbs.

research at Research Centre Hoogstraten
in Belgium has included the use of LEDs
to replace
incandescent bulbs for greenhouse production.
For more:
Gerson Van’t Wout, Hort Americas LLC,;
National Strawberry Sustainability Initiative, Research
Centre Hoogstraten (Proefcentrum Hoogstraten),

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Workshop focuses on starting an urban farm

Hort Americas attended the “Starting Your Urban Farm”
workshop in April in Fort Worth, Texas. Presented by Texas A&M AgriLife
Extension, the workshop started with a webinar by Texas A&M University
extension vegetable specialist Joseph Masabni. He discussed the basic requirements needed to start an urban farm including a plentiful water supply,
adequate soil type and desirable environment.

Masabni said one of the major pitfalls to operating a
successful urban farm is the lack of a marketing strategy. Since most produce
is perishable, it is critical that a grower have a marketing plan developed before
a crop is planted. He said development of markets and market plans are the
first steps necessary for profitable production. Because market windows are
narrow and precise, Masabni said growers need more options to sell their
products. Market-related questions that need to be answered include:

Where is the produce going to be sold?

How is the produce going to be sold?

What is the volume that will be sold?

What are the market windows for the produce?

What are the packaging requirements?

Urban farm tour

The second part of the workshop was a tour of Gnismer
Farms in Dalworthington Gardens, Texas. Owned by Lynn and Cynthia Remsing, the husband
and wife team farm 6 acres producing a variety of crops including asparagus, strawberries,
lettuce, cantaloupes, onions, rhubarb, kohlrabi, cabbage, potatoes, watermelons
and pumpkins.

Lynn Remsing, owner of Gnismer Farms,  uses
plant compost to grow his crops. He doesn’t use
any animal manures. 

Lynn Remsing said having the right soil is critical. He
composts wood chips he receives free from the local power company along with
grass clippings. He doesn’t use any animal manure.
Not wanting to be dependent on inconsistent and limited rainfall,
Remsing uses Netafim irrigation tape and black plastic mulch. During the hot
Texas summers when temperatures can easily exceed 100ºF, Remsing said using the mulch allows him to water
every 14 days. Remsing said he is working with Texas A&M to trial a double
layer of plastic mulch to determine its effect on production.

Gnismer Farms in cooperation with Texas A&M
University researchers is trialing a double layer
of plastic mulch to determine its impact on crop
production, including strawberries and lettuce.

Remsing is setting up another 360-acre farm in Waco,
Texas. To ensure that he has enough water for irrigation, he is installing a
couple of 40,000 gallon water tanks.
Some of the “tips” that Remsing offered workshop
attendees included: be willing to mechanize when possible, look for ways to
conserve water, don’t try to operate a farm on a shoestring and look for ways
to be able to sell your products before your competitors.
For more:
Gnismer Farms,

Visit our corporate website at

Organic Fertilizers with Dr. Danielle Treadwell at the University of Florida

Florida producers adding structures and organic
By David Kuack
An increasing number of Florida fruit and vegetable producers
are looking at implementing some type of protected environment production.
University of Florida-IFAS associate professor Danielle Treadwell said producers
are looking at a variety of structures including greenhouses, high tunnels and
hoop houses. She said some producers are looking at taking a portion of their
field acreage and adding covered production.
The reason for adding the structures varies. Treadwell
said producers are looking to take advantage of new or expanding markets for
specialty crops. Other producers plan to extend the season for crops that can
be damaged by freezing temperatures. Some producers are looking for
opportunities to expand their product mix with organically-grown crops.
Treadwell said market demand is the most important driver
for the construction of greenhouses, but that water is also a key factor.
“When you start talking about high tunnels and hoop
houses, producers are looking for water savings through better freeze
protection,” Treadwell said. “When there is a freeze in Florida the protection
is coming from overhead irrigation. A single farm can use millions of gallons
of water per freeze event. Producers of high value crops like blueberries and
strawberries are exploring high tunnel production to moderate the temperatures
under these structures and to apply less water.
“Florida producers are seeing increased restrictions on
water use,” she said. “They want to be ready. There are 18 million people in
the state so there is a high demand for water.”
Increased interest
in organic production
Some of the producers who have used traditional methods
and inputs are looking at taking advantage of the increased demand for organic
products. Treadwell said some of these producers have customers asking for
these products while others are looking to diversify their product mix. She
said this has led to producers asking suppliers for organic fertilizers
specifically for their crops.
“There are more manufacturers that are developing organic
fertilizers,” Treadwell said. “Some companies that have historically served
conventional farmers are now expanding their offerings because their customers
are diversifying.”
Treadwell said those producers who have adopted biologically-based
management strategies such as biological pest controls should have an easier
time converting to an organic production system.
“Producers who grow fruits and vegetables organically are
using biological controls,” she said. “There are very few controls approved for
use with conventional pesticides and even less for growing organically. When
you have an organic system in the greenhouse you have to rely on biological
controls. If you have an established biological program in the greenhouse you
are good to go. Through the efforts of university
and the producers we have done it and we have done it well here in Florida for
a number of years.”
organic fertilizers
Treadwell said producers seeking to implement organic
production and who already have a biological pest management system in place
should only have the fertilizer program to work out.
“How to keep the biology in the pot optimized so that
nutrients are transformed at a pace that the plants need–that’s the
challenge,” Treadwell said. “It’s finding that sweet spot of which fertilizer
to use, what analysis, and really honing down that application strategy.”
She said there are number of manufacturers that will
custom mix dry granular as well as soluble fertilizers that are compliant with
the USDA’s National Organic Standards.
“Producers can develop a relationship with a supplier
that does custom mixes and start experimenting to determine the best blend for
their crops. Then the next step is to put together a system of mixing tanks,
injectors and emitters that will deliver the fertilizer without clogging.”
Treadwell said it is best to mix the exact amount of
fertilizer solution that is needed. Holding the fertilizer solution at high
temperatures in the greenhouse can increase the rate of biological activity and
negatively impact the quality of the products.
A number of techniques have been tried at the university
to try to keep the fertilizer solution cool for a longer period of time. These
have included placing pop-up canopies over the tanks and injectors in the
greenhouses, wrapping the fertilizer tanks in reflective Mylar mulch and
submerging the fertilizer tanks in kiddy pools that contain recirculated well
“Because the fertilizers used in organic systems are
plant- and animal-based nutrients with some minerals added in, these liquids
are suspended particulates in solution,” Treadwell said. “It’s not like
ammonium nitrate, which is a salt with ions that truly dissolve in water.”
Finding injectors that can handle the particulates in organic
solutions can be an issue.
“The injectors do clog,” Treadwell said. “It’s also very
easy for algae to grow so it’s really important to flush the injectors well
after applying the fertilizer solution.”
She said high greenhouse temperatures can also take a
toll on fertilizer injectors.
Organic fertilizer
Treadwell said because most organic fertilizers are complexes
of multiple ingredients, the availability of individual ingredients may occur
at different rates. For this reason, she said, producers need to pay attention
to electrical conductivity levels during the season to have a better
understanding of release rates.
Even with the potential for excessively high or low soluble
salts, Treadwell said a limiting factor for certified organic fertilizers can
be the amount of nitrogen they contain.
“In compliant organic fertilizers the highest nitrogen
analysis available for dry granular fertilizers is around 15 percent,” she
said. “For solutions, the highest nitrogen analysis is around 5 percent. If
it’s greater than 15 or 5 percent, producers need to be sure that the
fertilizer is USDA compliant before they use it. That means a producer has to
apply quite a large volume of fertilizer in order to sustain the rapid growth
of the plants in a greenhouse because the temperatures are hot and the plants
are growing fast. It can be a little tricky, but it can be done. It just
requires a lot of management.”
Treadwell said using a combination of organic granular
and liquid fertilizers is helpful.
“It’s helpful to have a steady supply of nutrients in the
growing media using the granular forms and then supplementing with the liquid
form periodically through the season depending on the plants’ needs,” she said.

For more:
Danielle Treadwell, University of Florida, Department of Horticultural Sciences, (352) 273-4775;
David Kuack is a freelance
technical writer in Fort Worth, Texas,
Organic Fertilizers use in strawberries (Spanish).

The University of Florida has produced a series of online
educational videos called Virtual Field
( The videos present information on a variety
of topics (hydroponic production systems, soilless media, nutrient solution
delivery, pest management, harvesting and marketing) with visual support
including instructional how-tos. One of videos was made by associate professor
Danielle Treadwell who discusses the use
of organic fertilizers
in greenhouse vegetable production.Visit our corporate website at