Water soluble versus controlled-release fertilizer: All or nothing?

Feeding a greenhouse crop, like feeding any living thing, requires consistency. Any living organism that is underfed could run into health issues, such as disease pressure and poor growth. When it comes to greenhouse crops, that can mean lost revenue. But with so many methods for feeding plants, what method provides the most consistent and efficient nutrient delivery, and therefore most consistent and healthy growth?

The two most popular methods of feeding greenhouse crops include controlled-release fertilizer and water-soluble fertilizer. In capable hands, they can both provide the necessary nutrition for plants.

Nelson Gonzalez, Florida sales manager for Profile Growing Solutions, works in one of the epicenters of modern growing. He’s seen a lot of greenhouse growers and a lot of methods for feeding plants.  

“If you have the right practices in place and use the right fertilizer so the plants are fed as they should be, you’ll have a nice healthy crop,” he says.  

But there are considerations to make before choosing whether water-soluble options or controlled-release fertilizers like the comprehensive line of Florikan® products made by Profile Growing Solutions are best for your operation. Some of those considerations include cost, labor and efficiency.

Calculating the true cost of fertilizers

Controlling the cost of inputs is a top consideration for many growers. But it’s important to look beyond the initial cost of a single bag of fertilizer. Gonzalez notes that while some water-soluble or even cheaper top-dress fertilizers may look inexpensive at the outset, the costs compound with use over time compared to a controlled-release fertilizer, which he says is more of a “set it and forget it” option.

“In the long run, using a controlled-release fertilizer overall is just beneficial,” he says. “Some growers will use a cheap top-dress formulation, which is maybe a 30-to-60-day delivery of nutrients. That application is inexpensive when they put it out, but Nutricote® for example just needs one application for six months of feeding versus three two-month applications for the cheap options.”

The need for continual application of fertilizers that don’t have Florikan’s innovative technology that ensures a precise, predictable nutrient release means that the cost of inexpensive options will compound over time and possibly cost growers more. But more than that, controlled-release fertilizers have additional benefits that can save growers money.

One of those advantages, Gonzalez explains, is decreased weed pressure, particularly when using a subdressing method of feeding.

“If you are feeding a wide variety of crops, your Florikan productis sitting about an inch and a half below the top of the soil line. All the nutrients now need to run down through the column of soil before they're leached out of the pot,” Gonzalez says. “There's less weed pressure because you're only feeding the plant and not allowing your fertilizer to promote weeds.

So, with the proper application of a controlled-release fertilizer, growers will likely save on labor to remove weeds that may have otherwise grown on the surface of the media and herbicides to control weeds that can burden plant growth. Additionally, because controlled-release fertilizer is applied directly where it needs to go and, if you choose the correct formulation, it can deliver nutrients to the plant when it needs it most.  Leading to a far more efficient way of delivering the nutrition your plants need.

Understanding fertilizer’s impact on labor

Naturally, decreased weed pressure means that growers can make sure their labor force is focused on tasks that make their operation profitable. That’s a huge consideration in a time when wage pressure is making it more costly to produce an ornamental crop.

“It’s getting harder and harder for growers to find skilled labor,” Gonzalez says. “That’s the number one challenge that growers have. So, having a controlled-release fertilizer that can be incorporated into the potting line reduces the need for additional people to focus on feeding and weeding.”

Water-soluble fertilizer, in contrast, may require some additional labor. While most growers will have their water-soluble formula programmed or automated, it does require skilled labor to make sure that drip lines or overhead watering systems are placed on the plant correctly, secured well and that the system is free of debris.

And should a grower face weed pressure from their particular feeding method, there will likely also be a need for skilled labor to apply herbicide and remove the weeds from affected plants. That can mean time wasted on weeding, expensive personal protective equipment and long re-entry times after application, decreasing the efficiency of a grower’s workforce.

Considering fertilizer efficiency

The nature of controlled-release fertilizers like Florikan’s Nutricote or GAL-Xe^ONE® naturally maximizes efficiency. One application, generally at the potting line where labor is already required, allows for consistent feeding to match the life cycle of the crop.

Water-soluble feeding methods in the right hands can offer consistency as well, but they also need regular monitoring to ensure that nutrient levels are correctly balanced. This might mean regular testing of the growing media and tissue samples to ensure that proper levels are maintained, which in turn can add additional cost, labor and time spent adjusting the fertilizer mix to maintain optimal plant growth.

“There can be inconsistencies,” Gonzalez notes. “I've heard of growers that put in the incorrect rate or the incorrect product. Some growers may use three or four different analysis. If they use the incorrect rate or if their equipment is not calibrated correctly, they could provide too much or too little of the nutrients they intended to apply.”

Those mistakes can be costly and inefficient for the operation.

Rethinking fertilizer methods

Trialing is always the first step in making any change to greenhouse crop production. Gonzalez notes that Profile Growing Solutions, for one, has a robust staff of experts to help growers trial new methods of feeding their greenhouse crops. He notes that the first step is understanding the growers’ needs, pain points and what they hope to achieve. After gathering that information, a proper water-soluble versus controlled-release comparison can be achieved. And experts are available to answer any questions or address concerns.

But Gonzalez also notes that choosing a method of fertilization does not need to be an all-or-nothing situation. He suggests that growers looking to experience the Florikan difference through the application of Nutricote or GAL-Xe^ONE® controlled-release fertilizers can use them as a supplement to water-soluble solutions.

“Growers can establish a base feed with controlled-release fertilizer. Then, they can monitor and make the adjustments they feel they need through additional applications of water-soluble fertilizer,” he says. “Then, they can slowly ease into 100% controlled-release fertilizer if they feel that's what works best. But if not, they can still use controlled-release fertilizer as a consistent efficient base and while using water-soluble options to supplement. There's no harm in doing it that way.”

So, while there are strengths and weaknesses to every feeding method, it’s clear it doesn't have to be an all-or-nothing consideration. The bottom line? Growers need to make the choice that is the most efficient, consistent and labor-saving for their operation.