Plant Food and Fertilizing 101

Ellen C. Wells

Fertilizing your plants is as important as tasting and seasoning your dish at every step in its preparation. Or sharpening your figure skates before attempting an axel. Or wiping down your bowling ball before attempting to knock down that split.

Didn’t know you should be tasting and seasoning and sharpening and wiping? You can’t be faulted for not knowing the finer points of a process if you’re not well-versed in the cooking or skating or bowling culture. And your customers shouldn’t be disparaged for not knowing about feeding their plants, either. Unlike the other living things they are tasked with caring for (pets and children come to mind), their landscapes and planting beds don’t necessarily give them quick indications that they are needing an input of nutrients. Fertilizing plants isn’t one of those things people think is totally necessary—until they’re informed, that is.

As both your new and returning customers visit you to prepare for spring, you’ll want to be prepared to answer their most-pressing fertilizer-related questions. We spoke with some industry experts to see how best to respond.

“Do I Need to Fertilize?”

According to Mason Day, Head of Community and Support for JR Peters, the most prevalent question consumers have about fertilizing is as basic as it gets: Do I need to fertilize? That question is followed quickly by why.

The answer is super simple, too, Mason says—and very simply explained to customers. “All of the nutrients, especially when you think about fruits and vegetables, come from somewhere,” he says. “In a lot of these cases these nutrients are coming from the fertilizer. That’s particularly important if you’re using potting soil in a container. If you’re growing year after year, those nutrients are being taken up by the plants and removed from the soil. You have to replenish them. Basically, they have to eat, too, and they have to eat something that’s going to give them nutrients. So yes, fertilizer is essential.”

One of the barriers to fertilizer purchase and use is consumer skepticism about its necessity. That’s why answering the “But why do I need to?” question is so important. “I think a lot of consumers who don’t understand [the need for fertilizer] think that the garden center is trying to get an add-on sale like a car warranty,” Mason explains. “But it’s totally necessary.”

“When?”

Espoma’s Vice President of Marketing John Harrison uses the word “demystify” quite a bit when referring to answering consumer fertilizer questions. This is especially true with the common question about when to feed plants. Break it down as simply as possible. John says we see plants in most landscapes as being in two different groups (lawns notwithstanding): There are foundation plants, trees and shrubs and then there are what John calls “productive plants,” which he says are plants that produce something—flowers or food—during the growing season.

“Foundation plants, trees and shrubs generally want to be fed in the spring and late fall,” John advises. “But the plants that are producing all summer long—tomatoes, roses and so forth—they all need to be fed with regularity throughout the growing season because they need to keep up that production.”

“What and How Much?”

John says he recommends garden center staff suggest using organics, and it’s not just because Espoma is an organics company. Organic fertilizers, John says, tend to take their cues to start working from the environment. Soil temperature, for instance, is just one cue for organics to start releasing nutrients. “We also think they offer a bit of a margin of error,” he adds. “If someone does get a little carried away, organics do have a degree of safety in case you overapply.”

John explains that feeding at the time of planting didn’t used to be recommended because the salts could damage the roots. “When you’re using organics, they are very gentle and low in salts so we do recommend [feeding at time of planting].” John suggests including a product that has both starter fertilizer, mycorrhizal fungi and beneficial bacteria such as Espoma’s Bio-tone Starter Plus. “The idea with a high-value shrub in the landscape is to get the root mass to increase in size as quickly as you can so it takes up enough water and nutrients so it can get through its first drought,” John explains. “Once it does, it’s probably going to be there a long time.”

“Why Doesn’t My Plant Look Good?”

That may be one of the hardest questions to answer, but according to Kerry Meyer, Program Director for Proven Winners, this is a fertilizer-related question at its core. The first thing Kerry does when she gets this question is probe a bit further with follow-up questions: Where is the plant (landscape or container)? How and how often are you watering it? And finally, watering segues into, are you feeding it?

“What I’ll do is explain the two different types of fertilizer we have,” Kerry says, “the water soluble and how and why you’d use that and the controlled-release fertilizer and what that’s for. And then I explain how to use those two fertilizers in conjunction to make it through an entire season, whether that is for landscapes or containers.”

Referring specifically to annuals, Kerry suggests using controlled-release at the time of planting for both in-ground and container plantings. For landscapes, “because you’re planting in native soil, that should be sufficient for the season, unless you’re in an extremely long season such as in the South, and you may need a second application three or four months in.” Container plantings follow a different fertilizer regimen due to the non-native soil. “I tell them that usually for a container with annuals that first application of a controlled-release fertilizer lasts somewhere between two to three months,” Kerry explains. “If I plant in early May they start to need an extra boost around July 4th. That’s when I start to use the water soluble.” With the heat and the growing bulk of the plant material, the water soluble’s “instant energy” seems to be the thing you need to kick butt during the dog days of summer.

“How Often?”

The best answer to the “How often should I fertilize?” question is to suggest your customer read the instructions on the product’s label. But some folks ask this question hoping you give them an answer of not more than once. And not more than one type of feed.

“It’s not a one-and-done scenario,” Mason notes. “Your plants’ fertilizer needs are going to change depending on what they are and what the growing season is.” Some formulations of fertilizers are best for vegetative growth and others for reproductive growth. Mason uses peppers as an example. “If you feed peppers nitrogen throughout the entire season, you maybe will get two peppers but you’ll have massive plants. But if you give them a high nitrogen fertilizer in April and May for great growth and then switch over to a high phosphorus and potassium fertilizer from June onward, that’s when you’re going to get that great fruit set. Your plants use the amount of nutrients in the soil as a kind of barometer to know when to switch from one cycle of life to the other.”

Slightly confused about what should be fed which formulation when? Here’s Mason’s tip: When you go from wearing a long-sleeve shirt in your garden to wearing a short-sleeved shirt, that’s when you switch from a higher-nitrogen fertilizer to a higher phosphorus/potassium fertilizer.

These easily digestible answers should apply to most of your customers’ plant food inquiries. And it’s a good starting place from which they can explore more detailed instructions on their own. Who knows, plant feeding methods could be their new hobby. GP

Pictured: Garden Answer’s Laura LeBoutillier is an advocate of Espoma’s Bio-tone Starter Plus.
Pictured: JR Peters developed this social media infographic to help garden centers communicate the different fertilizers their customers might need.
Pictured: JR Peters developed some simple in-store “silent salesperson” signage to help communicate fertilizer practices to garden center customers.