If you want your perennials to grow up big and bountiful, then you’ve got to feed them right. Just like kids, they need the proper nutrition in order to thrive. Thankfully, your plants probably aren’t as demanding or picky as your children. In fact, there are only three major nutrients plants need most: nitrogen, phosphorus and potassium. But each must be provided in its water-soluble form if plants are to absorb them.
Measure granular fertilizer carefully according to package instructions.
Photo Credit: ©2001 Dolezal Publishing/John M. Rickard
Sprinkle granular fertilizer directly on the soil, in a circular pattern beneath the edge of the plant’s drip line (the circle following the edge of the plant’s foliage). Use a hand fork or cultivator to mix the fertilizer into the top 2 inches of soil. Water thoroughly to dilute.
Photo Credit: ©2001 Dolezal Publishing/John M. Rickard
Measure out the proper amount of encapsulated fertilizer according to package directions.
Photo Credit: ©2001 Dolezal Publishing/John M. Rickard
Sprinkle the encapsulated fertilizer on the soil surface at the plant’s drip line. Use a trowel or hand fork to mix the fertilizer into the top 2 inches of soil. Water thoroughly immediately after application.
Photo Credit: ©2001 Dolezal Publishing/John M. Rickard
Carefully dilute the liquid fertilizer as its package directs, then apply over the plant’s root zone. Water-soluble foliar fertilizers are absorbed directly by the leaves. Apply both types with a hose-end sprayer. Be sure to only fertilize on wind-free days cooler than 85 degrees F.
Photo Credit: ©2001 Dolezal Publishing/John M. Rickard
To apply solid organic fertilizers, spread a half-inch layer around the base of each plant. Work the fertilizer into the soil, and follow with a good watering.
Photo Credit: ©2001 Dolezal Publishing/John M. Rickard
Nitrogen, in the form of nitrate salts, is used heavily by plants and soil microorganisms. But be careful about overfeeding your plants: Too much nitrogen promotes foliage growth at the expense of blooms. Since nitrogen is carried through the soil with water as you irrigate and is quickly depleted, however, it must be replenished often.
While phosphorus sticks around in the soil, it doesn’t migrate down like other nutrients. In fact, it’s best dug down into the soil where roots can access it. Potassium, on the other hand, leaches with water in all soils but clay, so it can reach the roots more easily. Of course, there are micronutrients (such as calcium, magnesium, iron and zinc) that plants can use, and they’re sometimes included in fertilizer blends. Do a soil test to determine if these nutrient boosts are needed.
Even though plants have just three major requirements, there are all kinds of fertilizer blends available to meet their needs. So how do you choose the best one? Well, start by ignoring the label that implies the product’s intended use such as “flower and shrub food,” and go straight to the package label. Most list three numbers separated by hyphens. They’ll appear as: 10-10-10 or 0-20-20, for example. These numbers reveal the percentage of each major nutrient (nitrogen-phosphorus-potassium – or N-P-K – in that order) found in the fertilizer by weight. Products containing all three major nutrients are called complete fertilizers, while those with equal amounts of all three are called balanced fertilizers. (Different kinds of plants have different nutrient needs, so be sure to find out if your plantings have special requirements by either reading the plant tag or checking with the Learn2Grow Plant Database.)
When it comes to types of fertilizers, there are two major kinds: Synthetic and organic. Synthetic fertilizers are manmade, while organic fertilizers mean the product is made from decayed plant and animal matter. Both fertilizer types come in many forms:
Synthetic granular fertilizers: Economical and widely available, granular fertilizers are used in planting beds or containers, especially as starter fertilizer for new plants.
Encapsulated synthetic and organic fertilizers: Coated with a resin or soluble sulfur, these capsules release nutrients over a long period of time, usually 3-9 months. They’re ideal for container plantings.
Liquid organic and synthetic fertilizers: Generally speaking, these nutrients are already mixed in water, so they’re ready for easy absorption. They’re convenient when applied to the soil or sprayed on foliage for a quick plant perk, but always supplement sprays with solid fertilizers for a sustained supply of nutrients. Be sure to check and carefully read the label – some products are concentrates that require dilution before application.
Spikes and tablets: These concentrated sources of chemical fertilizers are so strong that they sometimes damage plant roots, so use them with caution!
Solid organic fertilizers: There’s a host of naturally occurring products that provide nutrients. Some are animal in origin – including manure and blood meal – while others are vegetable-based – such as cottonseed meal and alfalfa pellets. Manure should be decomposed and aged before using it to avoid burning plants with too much nitrogen and urea. (Any packaged manure sold at nurseries and garden centers has already been aged and is ready to use.) Organic fertilizers improve soil texture and promote the growth of soil organisms, from microbes to earthworms. Most are less concentrated and slower-acting than synthetic fertilizers.
When it comes to feeding your perennials, be sure to fertilize when planting new plants and when perennials break dormancy in spring. Then fertilize again halfway through the growing season. (Hold off on applying fertilizer near the end of the growing season because it encourages new growth, which can easily become damaged by frost.)
No matter what type of fertilizer you use, always read and follow label instructions and measure fertilizer amounts carefully. (Too much fertilizer will harm your plants!) Wear protective gloves when handling fertilizers, and always water your plants well right after you’ve fed them.
