When To Fertilize Your Plants

Don't let your trees, shrubs, flowers, houseplants and veggies go hungry. Feed them at the right time, and they'll reward you with healthy growth.

September 04, 2019

Photo By: Gardeners Supply Company

Photo By: National Garden Bureau

Photo By: National Garden Bureau

Photo By: Gardeners Supply Company

Photo By: Proven Winners

Photo By: Proven Winners

Photo By: Proven Winners

Photo By: Proven Winners

Photo By: Gardeners Supply Company

Photo By: National Garden Bureau

Photo By: National Garden Bureau

Photo By: Gardeners Supply Company

Photo By: Bailey Nurseries

Fertilized and Unfertilized Plants

Well-fed plants are healthier and more attractive than those that are hungry for nutrients. There are many kinds of fertilizers you can use, including slow-release products that release nutrients for two or more months before they need to be reapplied. Liquid or water-soluble fertilizers are usually reapplied every week to 10 days. Choose the product that's right for whatever you're growing, and follow label directions.

Spring Peas

When it comes to fertilizing vegetables, there are three main groups: light, moderate and heavy feeders. Peas, beans, radishes, turnips and mustard greens are among the light feeders. Give them starter fertilizer when you plant; if they’re growing in compost-enriched soil, they probably won’t need to be fed again. For best results, do a soil test before planting to determine what kind of amendments and fertilizer your soil needs.

Beets

Vegetables that need moderate amounts of fertilizer are plants like beets, potatoes, okra and carrots. Start by planting them in loose, well-drained soil that’s been enriched with compost, and mix fertilizer in the planting holes or rows. They probably won't need feeding again.

Heavy Feeders in the Vegetable Patch

Vegetables that bear heavily, such as tomatoes, corn, peppers, squash, broccoli and watermelon, are heavy feeders. Most grow well with a 5-10-10 fertilizer mixed into the soil at spring planting. Once the weather becomes warmer, these veggies can benefit from a second application, or side dressing. Follow label directions on the product you're using.

Fertilizing Shrubs

Shrubs can be fertilized in early spring and most can be fed again, more lightly, in autumn. But wait about a month after the first fall frost, so you don’t stimulate new growth that will be killed back in cold weather.

Heuchera 'Cinnamon Curls'

Water your perennials the day before you fertilize, and apply the fertilizer about the time that new spring growth appears. Some perennials, such as daylilies, are heavier feeders than others, so you may want to feed twice more in the growing season, at 6-week intervals. A slow-release fertilizer is a good choice for the spring feeding. Follow up with a liquid fertilizer, if desired, in summer.

Fertilizing Annuals

Mix organic matter and fertilizer into your soil when you plant annuals, or use a packaged potting mix that has fertilizer in it. Make sure to water thoroughly, so the plant roots don’t get burned. Most annuals bloom heavily for several weeks before they need feeding again; then you can add a slow-release fertilizer or use a liquid or water-soluble fertilizer about every two weeks.

Fertilizing Vines

Vines and other woody plants, such as groundcovers, can be fertilized at planting and again in fall. If you miss the fall feeding, fertilize in early spring, before growth begins. Water thoroughly after feeding.

Fertilizing Seedlings

Seedlings don’t need fertilizer until their second set of leaves — the so-called “true leaves” — appear. Then give them a water-soluble fertilizer diluted to half-strength, and apply twice a week. If the seedlings are growing in potting mix with fertilizer already in it, you don’t need to feed them until you transplant them into the garden.

Fertilizing Bulbs

After you plant your bulbs in the fall, top dress them with a balanced 10-10-10 or 10-15-10 slow-release fertilizer or a product formulated especially for bulbs. Feed again in the spring, as soon as new growth emerges from the ground. Mix the fertilizer into the soil to avoid burning the bulbs.

Fernleaf Dill

Herbs growing in loose, well-drained soil enriched with compost don’t usually need much fertilizer. But frequent waterings will leach away some of the nutrients, so feed them with a light, all-purpose fertilizer about every three weeks during the growing season. You can also give them some compost tea about once a week.

Fertilizing Container Plants

Potting mix that has fertilizer in it will give your houseplants or other container plants a good start. But eventually, the nutrients will either be used up, or they'll leach out after frequent waterings. When your plants are ready for a boost, apply a slow release fertilizer that lasts for several months, or feed more often with a liquid or water-soluble fertilizer. Stop fertilizing if your indoor plant goes into a period of dormancy for awhile.

Sugar Maple in Fall

Traditional wisdom calls for fertilizing trees in early spring, if needed, but some research indicates that fall may be a better time. Wait a month after the first hard frost to feed; fertilizing while the temperatures are still warm and the tree is actively growing may lead to new growth that is killed back. For best results, test your soil and ask your local county extension agent for advice on what kind of fertilizer and how much to use.

Shop This Look