Petrus Langenhoven

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

19 articles by this author

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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.


Developing and mixing your nutrient solution is one of several very important steps in the production process. Mistakes are easily made when fertilizers are mixed. Not only does this have a cost implication, but also it can have severe consequences on production and therefore revenue. In the previous article Taking Care of Plant Nutrition in Your High Tunnel-Water Soluble Fertilizer Calculations, we have looked at basic calculations that is important when interpreting the fertilizer formulation in the bag and how to use that information to apply specific concentrations of mineral nutrients. In this issue, we will discuss what you need to consider when developing a nutrient program, and focus on key fertilizer characteristics and nutrient solution mixing tips. Developing a nutrient program A nutrient solution is just as good as the quality of the ingredients and the time spend on formulation, calculation and mixing. Fertilizer should be of a high[Read More…]


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Every grower will have to do some basic calculations when mixing a nutrient solution. Understanding some of the calculations will help you to apply the correct concentration of a nutrient or determine the concentrations of a combination of nutrients applied. In the previous article Taking Care of Plant Nutrition in Your High Tunnel-Water Hardness and the Removal of Unwanted Ions, we have discussed how to manage hard water, and unwanted high concentrations of sodium, chloride, iron, manganese and sulfur. Growers have different nutrient solution mixing and application options. Depending on the size of your high tunnel or greenhouse operation and the sophistication level of your nutrient solution application system, you might decide to use a single-bag mix (contains all needed elements), a two-bag mix (Tank A-calcium and iron, and half of potassium nitrate; Tank B-all other elements including phosphates and sulfates), or an individual element mix (individual compound fertilizers). The[Read More…]


It is essential, especially in hydroponics to start with a laboratory analysis of your source water. It is also important to do follow-up analysis throughout the year. Water quality can change especially where the water source is a well or a pond. In the article Taking Care of Plant Nutrition in Your High Tunnel-Water Alkalinity (Issue 627), we have discussed the importance of water alkalinity and how to correct high alkalinity levels. Additional elements of importance are Ca, Mg, S, Na, Cl, Fe and Mn. Knowing concentrations of these ions can help you to determine the need to purify water, leach or bleed more frequently, as well as to avoid these contaminants by choosing the appropriate fertilizer. Hard water might be generally associated with high alkalinity, but it is not always the case. Water hardness is a measure of the amount of dissolved calcium (Ca) and magnesium (Mg), expressed as if[Read More…]


In the past I have had many conversations with growers about plant nutrition in their high tunnels. A good plant nutrient management plan is an integral part of making a success of the crop you are growing. Plant nutrition is important to grow a strong and healthy seedling, the first step of a successful crop. Fertility management of especially vining crops (e.g. tomato, cucumber, peppers) are critical to achieving a good yield. It does not matter if you grow your crop in soil or in a soilless production system. Steering your crop to have the optimum balance between vegetative and reproductive growth will result in good yields over a longer period. It is important for growers to know what is in their water and soil. Therefore, soil analysis of a representative sample of the area that will be planted, and water analysis of a water sample from the source that[Read More…]


In issue 619 and 620 of the Vegetable Crops Hotline newsletter I gave you a brief background of the materials used and methods followed during the variety evaluation. I also discussed some of the challenges we encountered while doing the trial work. The varieties evaluated included: Entry # Variety 1 Sephia (Galia type) 2 Tirreno (Italian netted cantaloupe) 3 Rawan (Ananas type) 4 Rowena (Ananas type) 5 Migdal (Galia type) 6 Magnificenza (Italian netted cantaloupe) 7 Kenza (Charentais) 8 Karameza (fully netted cantaloupe) Preliminary data will be discussed in this article. Statistical analysis of all the data has not been concluded and therefore only treatment averages are reported. Yield: One of the criteria that was set for the variety trial was that the fruit size needed to be between 2 – 4 lbs. At Meig’s Farm Magnificenza, Sephia and Kenza produced fruit that varied in weight between 3.28 and 3.96[Read More…]