A question many growers are asking is whether vertical farming of hydroponic lettuce production is profitable. Light requirement (daily light integral, DLI) of lettuce can vary from 15-20 mol/m2/day. Lettuce grown under low DLI has slow growth rate (i.e., takes longer to harvest) and appear poor in quality (elongated). Current estimate is that energy costs[Read More…]
Hydroponic lettuce is usually grown by continuously recycling the nutrient solution during production. As nutrients are absorbed by plant roots, stock solution is added to the recycled solution to maintain the electrical conductivity (EC) at a target level. Because plants absorb nutrients from the solution at different rates, the recycled solutions accumulates elements which are[Read More…]
Hydroponics Workshop II Greenhouse and Indoor based hydroponics for growing green leaf produce is rapidly growing near urban areas in Indiana. To bridge the gap in learning and increase the competitiveness of Indiana and Midwestern growers, Purdue Extension specialists and researchers in the department of Horticulture and Landscape Architecture have developed workshops that provide experiential[Read More…]
Pore space in soilless substrates Do you know that you are mostly paying for ‘pore space’ when buying a bag of soilless substrate? This is because, unlike mineral soils, nearly three-fourth volume of soilless substrates is pore space. I like to refer pore space as the ‘functional’ component of a substrate. By definition, pore space[Read More…]
Managing plant nutrition based on substrate EC is better than fertilizer solution EC as substrate EC directly measures the amount of nutrients in the root zone. There are both in-house and laboratory based methods of measuring substrate EC. One in-house method that is commonly used is ‘pour-thru’ technique. This technique is rapid, inexpensive and measures[Read More…]
Nitrogen (N) deficiency results in stunted plants that are chlorotic in appearance. Maintaining plant N status at an optimal level is important as plant growth is related to the tissue N content in many species. Currently, laboratory analysis is the only method available to accurately measure tissue N in plants. This method is expensive ($15-20[Read More…]
Krishna Nemali and Petrus Langenhoven (plangenh@purdue.edu, 765-496-7955), Department of Horticulture and Landscape Architecture, Purdue University A question many growers are asking is whether supplemental lighting is profitable for hydroponic lettuce production during the winter. We will address this specific question in this article. Light requirement (daily light integral, DLI) of lettuce can vary from 15-20[Read More…]