(Photos courtesy of the author)
West Lafayette, IN - Recent research in tomato production highlights practical approaches for improving seedling growth and maximizing yields in high tunnel systems. Healthy transplants are critical for organic vegetable production, but tomato seedling performance varies among certified organic growing media, largely due to differences in nitrogen supply. While general recommendations advise incorporating nutrients into media or applying supplemental fertilizers as needed, more precise guidance on nutrient sources and application rates is lacking. Because organic media differ in nutrient content and availability, growers need clearer information on when and how much supplemental fertilization is required for specific media.
A study on organic growing media found that tomato seedling performance varies
across commercially available substrates, and that supplemental organic fertilizer can
further enhance growth. The fertilizer was essential for growing media that did not
contain compost or other nutrient sources. In media that contained compost, the
fertilizer improved seedling nutrition, but did not consistently improve seedling size or
field performance. Sometimes the fertilizer resulted in excess salts in the growing
media. Identifying the right combination of media and fertility helps growers produce
strong, healthy seedlings that establish well and support vigorous plants throughout the
season. Growers can use standard laboratory tests for growing media to help identify
the need for supplemental fertilizer and potential for excess salts. Still, more research is
needed to understand how quickly nutrients become available in order to more closely
match supplemental fertilizer applications to the media.
In parallel, research on trellising systems in high tunnels shows that the stake-and-
weave method used without pruning tomato plants can produce higher tomato yields
compared to traditional double- or multiple-leader vertical-string supports used in
conjunction with pruning. This result occurred with a plant spacing that provided 8
square feet per plant and with harvest over an 8 to 10 week period. At a closer plant
spacing, or over a longer harvest period different results might be observed.
Together, these studies provide actionable insights for growers seeking to optimize tomato production from seedling stage to harvest. Implementing effective substrate management and selecting high-performing trellis systems can lead to stronger plants, higher yields, and more efficient use of resources.
According to Dr. Maynard, "I started the trellising research because various practices
are used by growers and it seemed useful to know how they might influence yield.
Growers choose tomato trellising systems with numerous considerations in mind. This
comparison between systems shows potential effects on tomato yield, size, and
marketing grade. I hope it will help tomato growers identify the system that best fits their
operation."
Author Dr. Petrus Langenhoven added "We aim for this research to foster collaboration between scientists, media producers, and farmers to develop nutrient release models that can be incorporated into product specifications, ultimately enabling growers to optimize transplant production practices for their specific operations."
Dr. Elizabeth (Liz) Maynard is Clinical Engagement Professor of Horticulture at Purdue University. She serves as an extension specialist for vegetable production, integrating education and applied research to improve vegetable farming. She collaborates with other Extension specialists, educators and agriculture professionals to create and deliver programs and resources for vegetable farmers.
Dr. Wenjing Guan is Clinical Engagement Associate Professor of Horticulture at Purdue University. She serves as an Extension specialist developing and delivering sustainable vegetable and fruit production practices to Indiana growers.
Dr. Petrus Langenhoven is Clinical Assistant Professor of Horticulture at Purdue
University. He serves as Horticulture and Hydroponics Crop Specialist supporting the
establishment and expansion of local and regional food systems by increasing the
productivity and efficiency of vegetable growers.
Dr. Lori Hoagland is Professor of Horticulture at Purdue University. Her research focus
in soil microbial ecology supports the continued growth and long-term sustainability of
local food systems.
The full articles can be read on the ASHS HortTech electronic Journal website at: https://doi.org/10.21273/HORTTECH05594-24 and https://doi.org/10.21273/HORTTECH05722-25
Established in 1903, the American Society for Horticultural Science is recognized around the world as one of the most respected and influential professional societies for horticultural scientists. ASHS is committed to promoting and encouraging national and international interest in scientific research and education in all branches of horticulture.
Comprised of thousands of members worldwide, ASHS represents a broad cross-section of the horticultural community-scientists, educators, students, landscape and turf managers, government, extension agents and industry professionals. ASHS members focus on practices and problems in horticulture: breeding, propagation, production and management, harvesting, handling and storage, processing, marketing and use of horticultural plants and products. To learn more, visit ashs.org.
