This Is the Worst Time to Fertilize Your Plants, According to Gardening Experts

Fertilizing is an important aspect of plant care, providing nutrients like phosphorous and potassium that will help your garden grow and flourish. However, the fertilizing process can often feel overwhelming, and leave first-time gardeners with more questions than answers. Which plant needs what? When is it a good time to add fertilizer? What happens if I make a mistake?

Fortunately, fertilizing doesn't have to feel so daunting—especially if you know what not to do. Here, we spoke with experts about the worst times to fertilize your plants, and what they recommend doing instead.

The Worst Times to Fertilize

Sometimes it's important to hold off on fertilizing. Doing so at the wrong time can end up doing more harm to your plant than good. With that in mind, you may want to avoid fertilizing in the following situations:

When Plants Are Stressed

Plant stress can occur for a variety of reasons; fertilizing under such circumstances is the worst possible timing. These situations can include prolonged drought, flooding, or major changes in light, according to horticulturist Jennifer Petritz.

A very intense heat wave can also be stressful for plants. "I avoid fertilizing during extreme heat, especially in the summer here in Arizona," says master gardener Angela Judd. "Plants may struggle to absorb nutrients, and any new growth pushed by fertilizer could be damaged by high temperatures."

When Plants Are Dormant—or Approaching Dormancy

If the worst time to fertilize plants is when they're stressed, then fertilizing late in the growing season is a close second.

"Autumn is when they're going into dormancy," says Petritz. "Fertilizing at this time of year can push tender new growth that won’t have a chance to harden off before winter. Even minor tip damage can severely affect a plant’s health and cold hardiness during a time of year when they should be concentrating on root growth."

"If a plant isn’t actively growing, it can’t use the nutrients you give it," adds Judd. "You risk waste or even root damage."

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The Best Times to Fertilize

It's equally important to know the best times to fertilize. "When we feed our plants, we’re telling them to grow, so it should be at a time when conditions are right for that growth," says Judd. 

Thankfully, choosing this time is easy when it comes to many plants. "The best time to fertilize is in late winter or early spring, just before plant bud break, when long-range forecasts show a warming trend with no signs of hard freeze," says Petritz.

Early spring is also when Judd recommends fertilizing. "We want to feed them when they can actually use what we’re giving them," she says. "For many plants, that’s early spring."

She also explains that with some plants, like roses or basil, it may be better to fertilize right after pruning. "Pruning encourages new growth, and giving them fertilizer at that time helps support that response," she says.

Fertilizing Tips

"Focus on feeding the soil, not the plant," says Judd. "Compost, worm castings, and organic, slow-release fertilizers improve soil structure and feed the beneficial microbes in the soil. Those microbes help break down nutrients into forms that plants can actually absorb."

"I like to use a balanced organic granular fertilizer," adds Petritz. "I pour some in a small bucket or pail and pretend like I'm feeding chickens, just scattering handfuls evenly across the root zone of my favorite plants. Because organic fertilizers can be a little smelly, I do it right before a good rain."