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THE FULL SCOOP ABOUT FERTILIZERS
by Nanette Londeree, Master Rosarian
“You are what you eat,” or so the saying goes. As much as you love chocolate, think what you’d be like if that’s all you ate! Plants, like people, thrive on a well-balanced diet. Imagine you’re on a tropical island, and your kitchen (your only source of food) is stocked with a huge variety of fruits, vegetables and nuts, meat, fish, poultry and dairy, everything you’ll need to stay healthy - for a month. You’ve also got oodles of boxes of corn flakes. You can’t leave the island to get any more food – you have to subsist only on what’s in your island kitchen. You’ll do great for that first month, but after that? Cornflakes three times a day, every day with no reprieve? While it may be enough to keep you going, it’s not likely to keep you filled with energy and healthy enough to fight off disease after a few months. Guess what? Your roses aren’t any different. Both you and your roses need an array of nutrients to be at your best.
Growing healthy roses that produce bountiful blooms and are able to fend off disease require the basics of light, moisture, air and nutrients. You take care of the light and air when choosing an appropriate planting location, and supplement Mother Nature for needed moisture and nutrients through irrigation and fertilizing. Providing the right amount of water at the right time is essential to healthy plants; similarly, ensuring that the right nutrients are present and available to the plant when they’re needed is just as important.
We gardeners routinely describe fertilizing as “feeding” our plants, but that’s not really accurate. Plants “feed” themselves, producing their own food in the form of sugars through the process of photosynthesis. We add plant nutrients, those chemical elements necessary for plant growth, to supplement those naturally occurring in the soil. In a forest under natural conditions, fallen leaves and dead plants slowly decay; they continually replace nutrients taken up by living plants and provide a steady, balanced level of nutrients. That same cycle of continual replacement isn’t generally available to cultivated plants without our intervention. Even if you’re lucky enough to start with great garden soil, as your roses grow, they absorb and remove nutrients from the soil leaving it less fertile. By adding materials to the soil through fertilizing, you’re making the desired nutrients available to the plant.
How About Coffee Grounds?
After your cup of joe in the morning, don’t toss the grounds in the garbage! They can be a beneficial addition to your garden soil. Grounds from your coffee maker are reported to be slightly to highly acidic (similar to peat moss), depending on the source of the coffee beans. They’re a low level source of nitrogen (NPK ration of 2.0-0.3-0.2) as well as a minor source of calcium and magnesium. They can lower the pH of soil, so they’re best used in the soil of acid-loving plants like rhododendrons, azaleas and blueberries.
So how do you decide what to feed your soil? Roses have the undeserved reputation of being demanding plants that need lots of fertilizer. That’s not necessarily the case. While it’s likely you’ll get bigger flowers and more of them by adding key nutrients, in general, they don’t need lots of supplemental nutrients to be healthy and bloom. What fertilizers you use, and when you use them depends on what do you want from your plants along with the nature of the soil and the environmental conditions they are growing in. As an example, an avid rose exhibitor is likely to have a more aggressive fertilizing program, providing greater quantities of nutrients more frequently than the gardener who’s happy with simply flowerful plants. Roses planted in a shady location grow more slowly, absorbing nutrients at a lower rate than those planted in full sun, so don’t need to be replenished frequently. A young, developing rose plant with few leaves won’t use some nutrients as quickly as a fully mature plant would, but may need others in order to develop a strong root system. Other considerations when choosing a fertilizer include the cost of the material, the ease of use, and any potential impact on it may have on the environment.
Back to a balanced diet. Plant nutrients can only do their job if the other basic requirements for growth are met – adequate light, air and water. Fertilizers not only won’t help plants growing in water-logged or moisture-deprived soil, they can actually end up damaging plants. Over-dosing with some nutrients like nitrogen can burn tender roots and foliage and stimulate excessive new growth that actually attracts sucking insect pests like aphids. Once again, adding the right material at the right time can give you the results you desire.
There are plenty of products you can buy at your local garden center, but not all valuable fertilizers come in a bag or bottle. Ever tossed used coffee grounds around the base of a potted plant, or dug banana peels into the soil? Mixed a scoop of wood ashes in when planting a new rose? Top-dressed the soil with worm castings? All serve as fertilizer by providing nutrients to the soil as they break down, but cost little to nothing, and can provide some nutritional benefits.
In the coming months, we’ll explore the world of plant nutrients, fertilizers and feeding both your soil and your roses, clarify what a fertilizer is and what it does, look at the myriad types of available fertilizers, consider the many options of how and when to fertilize, delve into amendments and additives, and identify some nutritional deficiencies that may plague your plants and options to remedy them. Next time, we’ll focus on basic plant needs and growing conditions.
Now, where should I put those coffee grounds?
Photos by the author – The only fertilizer the healthy and floriferous roses, ‘Gemini’ and ‘Ballerina’, get is a mulch of composted duck manure once a year.
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Last Modified: 08/06/2013