Petrus Langenhoven

Horticulture and Hydroponic Crop Specialist
Department of Horticulture and Landscape Architecture
Petrus Langenhoven's website

24 articles by this author

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We are pleased to announce that the 2020 Indiana Horticultural Conference & Expo (previously known as the Indiana Horticultural Congress) will be from February 11 through 13, 2020 at the Indianapolis Marriott East Hotel, located in Indianapolis, IN. There are numerous and very exciting changes that will occur at IHC 2020. Additional tracks are added to the already great lineup of previous years. New tracks such as Urban Agriculture, Hemp Production, Agronomic Crops, and Woman in Agriculture will create additional opportunities to serve our audience. A targeted selection of educational tracks, a joint plenary session, a diverse set of expo vendors and ample opportunities for networking will set the stage for a great conference. A trade show lounge featuring coffee and couches will allow an abundance of networking opportunities with fellow Indiana and other Midwestern farmers and vendors. Educational Tracks Wine Grape Food Safety Fresh Vegetables Organics* Raw Products Fruit[Read More…]


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Finally the time has come to plant warm season crops. Zucchini is a popular summer squash grown throughout Indiana and the United States. It always delivers a bounty of fruit. Yes, technically zucchini is a fruit (botanically classified as a modified berry) but as per the USDA it is listed under the ‘Vegetables and Vegetable Products” food group. Zucchini have a multitude of fruit colors and flavors. Therefore, this makes a great vegetable to present to consumers. Characteristics of zucchini – Typically, zucchini is non-vining and bushy but some varieties could have a creeping habit. Some varieties have prickly trichomes on both the stems and leaves. Male and female reproductive structures are produced on the same plant but in different flowers. The large yellow-orange unisexual flowers (a flower that possesses either stamens or carpels but not both) attracts bees, beetles and other insects to pollinate the flowers. The pollen is[Read More…]


Figure 2. Wilt of watermelon seedlings due to grown in a high EC medium.

Producing healthy transplants is a critical step for a successful growing season. Choosing the proper growing media is an important first step. Supported by a USDA Specialty Crops Block Grant through the Indiana State Department of Agriculture, researchers from Purdue have been evaluating different organic growing media with and without adding supplemental organic fertilizers for tomato and cucurbit transplant production. In this article, we have highlighted a few transplant symptoms that are associated with growing media with excessively high or low electrical conductivity (EC) or pH. It is always a good idea to test EC, pH, and other important nutrient content of a medium when you are making your own or using an unfamiliar media. Most soil laboratories provide a saturated media extract test that provides information on these important parameters. More information about this test and suggested range of EC and pH can be found in this article http://www.soiltest.uconn.edu/factsheets/InterpSMEGreenMedia.pdf[Read More…]


On April 1, 2019, Dr. Hazel Wetzstein, Head of the Department of Horticulture and Landscape Architecture, announced a change in leadership for the Indiana Horticulture Congress. “I am pleased to announce that Petrus Langenhoven and Kyle Daniel have agreed to serve as Co-Chairs for the Indiana Horticulture Congress, effective immediately. They bring a wealth of information and experience and I am looking forward to the leadership they will bring to IHC”. Peter Hirst, will be stepping down as chair. He is going to maintain a program in Pomology in the HLA Department and will assume an active international role as Assistant Director in International Programs in Agriculture (IPIA). “We all wish to thank Peter for his dedication and many years of service as IHC Chair. It is important to note that the past successes of Hort Congress would not have been possible without the dedicated efforts of Lori Jolly-Brown and[Read More…]


Basic Aspects of High Tunnel Soil Fertility Management – (Petrus Langenhoven, plangenh@purdue.edu, 765-496-7955) – Spring has arrived! Every high tunnel grower is now thinking of planting summer vegetable crops in high tunnels or has already planted. Whichever scenario applies to you, I hope that you have submitted soil samples or are in the process of submitting samples to your closest laboratory. Have you analyzed your irrigation water? It will be a good idea to send a water sample along too. There is a lot of important information locked up in your water and soil test results. The results will help you to plan and manage your high tunnel fertility program. Remember, growing in a high tunnel is like growing crops in an irrigated desert. Natural rainfall is unavailable inside your high tunnel and therefore all your plants water needs are satisfied through an irrigation system. Fertilizer needs could be addressed[Read More…]


Sweet colored peppers can yield well in the protected conditions of an unheated high tunnel, but information is lacking about which varieties are adapted for high tunnel production and their performance. During 2018 we evaluated ten sweet pepper varieties at the Purdue Student Farm, West Lafayette, Indiana (Table 1). How was the evaluation conducted? The evaluation was conducted on a Mahalasville (Md), silty clay loam. The spring soil test showed 9.5% organic matter, pH 7.5, and 201 ppm phosphorus (P), 250 ppm potassium (K), 810 ppm magnesium (Mg), and 4200 ppm calcium (Ca). The cation exchange capacity was 28.4 meq/100 gram. Micro nutrients tested at 11.5 ppm zinc (Zn), 34 ppm manganese (Mn), 100 ppm iron (Fe), 2.7 ppm copper (Cu) and 2.9 ppm boron (B). Nitrogen, 60 lb. N/A from Nature’s Source® Professional 10-4-3 liquid plant food, was applied by fertigating 15 lb./A N four times at 2, 4,[Read More…]


Gowers always want to know which variety is the most suitable one for their farming location and market. I do understand the frustration of growers when looking online at all the varieties being sold by different vendors. There are a plethora of varieties available that have different fruit types and growth habits. Characteristics like potential yield and disease resistance are always important considerations for growers. Which variety will work best for my farming operation and market? During 2018, I attempted to address growers’ concerns and need for local variety performance data, hosting a zucchini field trial at the Throckmorton Purdue Agriculture Center/Meigs Horticulture Facility, Lafayette, Indiana. How was the evaluation conducted? Soil of the test plot comprised of a Toronto-Millbrook (47%) complex, Drummer (27%) and Starks-Fincastle complex (26%) (ranged from a silt loam to silty clay loam). The spring 2018 soil test showed 2.8% organic matter, pH 5.7, and 34[Read More…]


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Getting seedlings off to a good start begins with a good growing medium for transplants. Growing media for organic production must meet the guidelines set out by the National Organic Standards Board, including not containing any synthetic substances (unless they have been approved for that use) or any prohibited materials. A number of products meet those criteria, and many of them are listed by the Organic Materials Review Institute (OMRI) to document that they meet the criteria. Last year, with funding from a USDA Specialty Crops Block Grant through the Indiana State Department of Agriculture, a group at Purdue began evaluating commercially-available, OMRI-listed growing media for vegetable transplant production (Table 1). Table 1. Growing media used in transplant production trials, 2018. Product Abbreviation Source Johnny’s 512 J512 Johnny’s Selected Seeds Morgan Composting 201 M201 Morgan Composting Penn Valley Potting Soil PENN Penn Valley Farms PromixMP Organik PMPO BFG Supply Seed[Read More…]


Figure 1: Field study at Meigs Horticulture Facility

While Indiana remains a key player in the domestic cantaloupe market, commercial field production is limited to a few counties. The total acreage planted in Indiana peaked in 1997 at 3,600 acres with a total production of 455,000 cwt and an average income of $16 per cwt (USDA ESMIS, 2015). Indiana cantaloupe growers have lost a significant share of the melon market since the 2011 and 2012 food borne illness outbreaks. Compared to 2011, the acreage planted and production in 2016 decreased by 900 acres (33%) and 257,000 cwt (45%), respectively. At $23 per cwt the 2016 farm value of production was $7,245 million, $35,000 lower than in 1997. Increased competition from neighboring states, the higher production risk due to food safety related issues, the limited selection of melon types and technologies that can be used to increase production and product quality has led to this tremendous decrease in planted[Read More…]


In the past season, we tested performances of eight specialty melons grown under high tunnel, greenhouse, hydroponic, and conventional field systems. The melon varieties we have tested in our trials include Lilliput, Inspire, Sugar Cube, French Orange, Tasty Bites, Escorial, Savor, and Artemis. Many of these melon varieties are Charentais (Cucumis melo var. cantalupensis). A specialty melon type with an outstanding fragrant smell. If you are wondering how to grow these specialty melons, please follow us at the Indiana Hort Congress. We will present what we have learned about growing these specialty melons under different production systems.