Your Guide to Crop Steering With Nutrients
For several years, commercial cultivation has been a trial-and-error process for growers as they navigate the most efficient way to care for plants throughout the different life cycle stages.
During each stage, plants must have specific plant essential nutrient ratios to develop, grow or produce at its best. If a plant has too much or too little of one of the 14 essential plant nutrients, it will not complete its life cycle stages correctly, says Ian Bateman, who works in professional technical services at Hawthorne Gardening Company Horticulture Division.
“When you think of the plant body, it’s like a skyscraper you’re trying to build,” Bateman says. “All the nutrients are pieces of equipment, machinery or structural components that help make that building. So, if you have one missing piece out of the equation, you can’t finish your building, and that’s how I would think about plant nutrients. If a grower has just one out of the 14 nutrients, that isn’t sufficient to sustain the growth level they want, then, the growth is slowed down by that nutrient.”
Knowing what to feed a plant when it needs it will help save time, money, and most importantly, the plant. Additionally, understanding essential plant nutrients and maintaining proper ratios can help with crop steering, Bateman says.
Cultivators use crop steering to direct the plant to grow in the way they want by altering the environment, how often plants are irrigated and other inputs. Growers can steer the plant’s growth and habit by adjusting nutrients, as well, another important component of crop steering, Bateman says.
In order to use nutrients to steer crops, Bateman suggests these key considerations.
Timing is Key
Different nutrients contribute to different aspects of plant growth and development. For example, nitrogen and iron help plants develop strong leaves to capture light, Bateman says.
Nitrogen and iron are most useful when the plant is in the vegetative stage, when it grows larger, and when stems and leaves are developing, Bateman says. Growers can use these key nutrients to help boost growth and ensure the plant is ready for flowering.
“The opposite is also true when it comes to getting the plant to fruit or to flower,” Bateman says. “We want to taper back those vegetative signals to the plant and start bringing in some nutrients that encourage the plant to focus on flower production.
To steer the plants to flower, elements such as potassium, phosphorus, sulfur and calcium become more important during that cycle. By changing the levels of these individual nutrients, a grower can start to tailor the plants growth in a way that is beneficial to them, Bateman says.
Why More Nutrients is Not Always Better
It’s essential to have all of the nutrients in the right proportion for the plant. Growers must navigate a fine line of having the optimum amount of all 14 nutrients to get the plant to grow as optimally as possible, while avoiding too much or too little of each nutrient, Bateman says.
“The plant pulls up the nutrients and water continuously, and if the plant has too much of one nutrient, the plant doesn’t have anywhere to put it,” Bateman says. “It can’t store it past a certain threshold, get rid of it or use it, so it starts to become toxic in the plant body. If you’ve heard someone say, ‘I burned my plants.’ or ‘They’re curling over,’ this is when one or more nutrients have been overapplied and accumulated to toxic levels and the plant starts to become sick and grow slower.”
One example is iron, Bateman says. « Iron’s primary role in the plant is it’s involvement in the synthesis of chlorophyll. You can think of nitrogen, magnesium, and carbon as the fundamental structural components of chlorophyll, and iron comes in and helps build it. »
During the plant’s vegetative stage, growers should provide the plants with a significant amount of iron to build chlorophyll. Then during the flowering cycle, cultivators will want to reduce the rates of iron fertilization as the plant is not focused on leaf development anymore and it may not be able to store any more iron, which can cause the plant to burn or show signs of iron toxicity, Bateman says.
« There are other nutrients like boron and manganese that are also involved in various stages of plant metabolism, » Bateman says. « Generally speaking, when a plant gets to the flowering stage, the grower will want to start ramping these nutrients down because they are already built up in the plant. So that’s why some nutrients in excess can hurt the plants. »
Tailoring Nutrients to Plant Growth Stage: What it Means and How it Works
In the hydroponics industry, it’s common for growers to have a different set of fertilizers for the plant’s vegetative and flower stages, Bateman says.
“The flower fertilizers are lower in nitrogen, broadly speaking, and have higher levels of phosphorus, potassium and calcium,” Bateman says. “The vegetative set of fertilizers tend to have higher iron, nitrogen that help the plant grow leaves, stems and roots.”
The goal is to give plants exactly what they need during their different life cycle stages. Bateman suggests different products growers can use to help crop steer plants by tailoring nutrients to the plant’s development.
For example, Botanicare Pure Blend Pro plant food blends are formulated for specific stages during the crop’s lifecycle; Grow includes essential nutrients needed during the vegetative stage, while Bloom gives plants what they need during the flowering stage, Bateman says.
“With those two bottles of fertilizer, a grower will already be 80% there; however, there are limitations to changing those two bottles because there are 14 essential plant nutrients,” Bateman says. “The Pure Blend Pro supplies quite a few of those nutrients, but how does a grower adjust individual nutrients to give the plant exactly what it wants no more, no less when every one of those nutrients is just in two bottles?”
It can be challenging to increase or reduce specific nutrients, but that’s where nutrient supplements come in, Bateman says.
Botanicare Hydroplex, for example, provides a boost of primarily phosphorus and potassium to help maximize flower size.
“A grower can combine the Hydroplex with the Pure Blend Pro to ramp up the phosphorus and potassium while still keeping the nitrogen low and iron in check to ensure they are still giving the plant exactly what it wants when it needs it,” Bateman says. “Hydroplex is a great example where a grower can add a little extra horsepower in bloom by giving the plant just what it needs to tailor the precise amount of phosphorus and potassium.”
The nutritional needs of crops are not constant, as they shift over time in terms of overall concentration and composition, which means growers should apply different proportions and quantities of all 14 plant essential nutrients to best support the needs of their crops as they develop, Bateman says.
“Nutrients, supplements are all tools in the toolbox, which should be deployed strategically,” Bateman says. “Don’t bring tweezers to a job-site and don’t bring a sledgehammer to perform open heart surgery. Be strategic. Strive to give your crops what they want, when they want it, no more, no less.”