Fertilizers

You know that your vegetable garden and rose bushes need some extra nourishment, but how do you go about choosing the right fertilizer? There are many varieties available, so it's good to gain some basic knowledge about fertilizers before you go shopping. Because pH levels affect the ability of soil to release fertilizer nutrients, you will first need to test the pH of your soil. Luckily, testing your soil is relatively easy. Most local Cooperative Extension Services provide tests for a small fee. Before you buy fertilizer, consider the following questions:

• Do you need fertilizer for plants in containers or in your garden?
• Will you need a fertilizer that works immediately or over time?
• What do the numbers on a fertilizer package tell you?
• Have you ever applied fertilizer to your vegetable garden?
• Would an all-purpose or specialized fertilizer work better for you?

Types, Application Tips and Nutrients

Before buying fertilizer, you must first do some research into the different types available. The three-number code on the fertilizer package indicates the amount of its three primary ingredients -- nitrogen, phosphorus and potassium. Different plants and vegetables need varying concentrations of these nutrients and other elements. Fertilizers are created in a range of different formulas. So, depending upon the types of plants you are working with and the soil pH, you are sure to find a formula that works well for you. Fertilizers can be applied differently, so it's best to familiarize yourself with some application tips beforehand.

Types: There are four main types of fertilizers -- organic, granular, water soluble and synthetic. Organic fertilizers are made from natural ingredients and have a slow release, meaning that the materials in these fertilizers must be broken down by soil microorganisms for the gradual release of nitrogen and other elements. Dry, granular fertilizers are the most popular type and work by releasing small quantities of nutrients each time the plant is watered. Water-soluble fertilizers are easy to apply and make nutrients immediately available to plants. Synthetic fertilizers act fast and provide an immediate greening effect, although the effects may be shorter lived.

• Organic fertilizers contain lower nutrient levels than other types of fertilizers
• Organic fertilizers are the least likely to cause "fertilizer burn" on plants
• Granular fertilizers work well for vegetables and perennials
• Use water-soluble fertilizers with annuals and container plants
• Synthetic fertilizers are easier to transport and are less bulky than organics

Application Tips: Different types of plants need varying amounts of fertilizer, so make sure to follow the instructions found on the fertilizer package label for best results. Work organic fertilizers into the soil before you plant, then around your plants afterwards. With granular fertilizers, measure out the required amount and sprinkle lightly around the bottom of the plant, mixing the fertilizer into the soil. Mix water-soluble fertilizers with water then apply using a watering can or sprayer. Synthetic fertilizers require more work because the results are short lived, so you have to apply this type more frequently.

• Applying too little fertilizer leaves plants undernourished, while too much can burn plants
• Temperature affects organic fertilizers so nutrients may be unavailable in spring or fall
• To avoid burn from synthetic fertilizers, water thoroughly after application
• Regular application of fertilizer results in healthier, greener leaves
• Applying granular fertilizer in windy conditions results in uneven application

Nutrients: Every fertilizer package features three numbers that indicate the percentage of primary nutrients included in the fertilizer -- nitrogen, phosphorus and potassium. For example, a fertilizer showing 5-10-5 on its package has 5% nitrogen, 10% phosphorus and 5% potassium. Depending upon the type of plant you are fertilizing and the growth stage of the plant, look for higher or lower levels of these chemicals. Labels also indicate other chemicals, called secondary nutrients, that are included in lesser amounts. Examples include calcium, magnesium and sulphur. Even smaller amounts of nutrients, or "trace elements," are used to encourage different aspects of plant growth.

• Nitrogen is used in the early growth stage to help plants achieve leaf root growth
• Nitrogen can damage plants, so avoid direct contact with leaves
• Formulas higher in phosphorus are used for plants nearing the flowering or fruit stage
• Fertilizers high in potassium promote fruit growth and won't burn plants
• Iron is a trace element that augments poor soil and helps plants stay green

Fertilizer Nutrient	Symbol	Used For	Examples
Calcium	Ca	Improving plant vigor and promoting growth of young roots and shoots	Calcium benefits tomatoes by promoting plant growth and decreasing the potential for blossom-end rot
Magnesium	Mg	Regulating absorption of plant foods and helping in seed formation	Azaleas, camellias , rhododendrons, blueberries and mountain laurel require acidic soil so they do well with a fertilizer high in sulfur, magnesium and iron to encourage deep, green leaf color
Nitrogen	N	Green, leafy growth and plant development Blood meal fertilizers are applied to gardens lacking nitrogen	Lawns need high levels of nitrogen because they are constantly growing new, green leaves
Phosphorus	P	Strong roots and healthy fruit and seed formation; increases blooms	Flowers usually need a fertilizer high in phosphorus to encourage blooms
Potassium	K	Vigorous growth and disease resistance, improving overall plant health and increasing cold hardiness	Use fertilizers high in potassium to encourage fruit growth
Sulfur	S	Maintaining dark green coloring; promotes vigorous plant growth	Azaleas, camellias , rhododendrons, blueberries and mountain laurel require acidic soil so they do well with a fertilizer high in sulfur, magnesium and iron to encourage deep, green leaf color

Features

Flower: Special fertilizers are available just for flowers. Many are water soluble, which work especially well for annuals. Flower fertilizers are typically higher in phosphorous or may contain equal amounts of nitrogen and phosphorus.

Rose: Roses need more fertilizer than any other type of landscaping plant and thrive on regular feedings of slow-release fertilizers high in nitrogen. Rose fertilizers include a special mixture of nitrogen, phosphorus and potassium to encourage continued blooming throughout the growing season.

Vegetable: Special fertilizers uniquely formulated for vegetables are often granular or controlled-release fertilizers that provide deep penetration into the soil where small amounts of the nutrients are released as the vegetables grow and as rainwater penetrates the soil. These types can last for three to six months, based on the variety and the amount of water in your garden. Vegetable fertilizers contain nitrogen, phosphorus and potassium.

Houseplant: Fertilizer designed for houseplants, also called "plant food," is typically available in granular or water-soluble forms, such as crystals, liquid or tablets. You can use houseplant fertilizer to encourage plant growth, increase blooms or to simply maintain the plant's health. Houseplants are container-bound and eventually need more nutrients than they can get from their potting soil.

Liquid: Spray liquid fertilizer on plant leaves or pour directly on root systems, depending upon the manufacturer's instructions. Because it is water soluble, liquid fertilizer is quickly and easily absorbed into a plant's root system for an immediate boost. Liquid fertilizers quickly leach into soil so they need to be applied more frequently than other types. Liquid fertilizers can also help prevent transplant shock.

All-Purpose Fertilizer: All-purpose fertilizer works on all flowers, vegetables, trees, shrubs and houseplants and is appropriate for soil that is fairly balanced.