Three best garden fertilizers
Garden fertilizer is essential for a lush, leafy garden, especially if your soil is lacking in key nutrients. Not all soil is healthy enough to grow what you've planted, even if you've used potting soil. And plants themselves can leach nutrients from the soil. The right garden fertilizer will make up for nutrient-poor or imbalanced soil by depositing the right amount of macronutrients for your garden to flourish.
Here's everything you need to know about the different types of fertilizers available on the market as well as a breakdown of the macronutrient ratios you can expect to find on a bag, box, or bottle of garden fertilizer.
Considerations when choosing garden fertilizers
There are three main types of garden fertilizers, which differ in form, application, and advantages.
Granular fertilizers are dry and similar in appearance to oversized grains of salt. This type of fertilizer is applied with a spreader or built-in shaker. A benefit of granular fertilizers is that you can easily control the application and see how much you're spreading on top of the soil.
Slow-release granular fertilizers offer a steady release over time and don't require frequent application.
Quick-release granular fertilizers deliver an immediate fix of nitrogen to your plants. This isn't intended for general use, because it can harm plants, but to target a specific deficiency.
Liquid fertilizers generally need to be diluted in water, such as mixed in a watering can and applied to the soil via the canister or a hose with an attachment. Though liquid fertilizer requires frequent application, its nutrient content is quickly absorbed by plants. Be aware that it can wash away easily in the rain and contaminate water sources nearby.
Spikes are fertilizers compactly contained in a spike that you stick in the ground. You can't really go wrong with this convenient fertilizer. You don't have to concern yourself with dilution or precise measurements to get results.
Fertilizers come with a ratio on their bag, box, or bottle. It is simply the ratio of macronutrients-- nitrogen (N) to phosphorus (P) to potassium (K)--that's in the formula. For instance, a 4-4-4 NPK means a 1:1:1 ratio of 4% nitrogen, 4% phosphorus, and 4% potassium (the rest is filler).
Each nutrient will help your plant in different ways. Nitrogen is for lush, leafy growth. Phosphorus is for fruit growth, flowering, and root growth. Potassium is for protection against disease and to promote root growth.
Synthetic vs. organic
Garden fertilizers come in synthetic and organic formulas. Synthetic fertilizers are available in both granular and liquid types. They release nutrients more quickly and are cheaper than organic formulas.
Organic fertilizers release nutrients more slowly and are less harmful to plants and the surrounding environment. Organic formulas may include blood meal with a high phosphorus count and bone meal for calcium. Be aware that these two alternatives are animal byproducts. Kelp, fish emulsion, manure, and compost are other natural alternatives.
Garden fertilizers range from $10 to $80. Expect to pay between $0.10 and $0.50 per square foot. Smaller bags for container plants shouldn't run over $20. If you're looking to fertilize a lawn or garden, it's most cost-effective to buy a bigger, more expensive bag or in bulk. Just like with supermarket produce, expect to pay more for organic than for synthetic fertilizers.
Q. What's the best season to apply fertilizer?
A. When it comes to outdoor plants, you don't want to waste your money on a fertilizer that will be blown or washed away by the elements. This is why we recommend the following application guidelines. For perennials and vegetables, apply fertilizer in the spring. For trees and shrubs, it's best to apply in the spring or fall. For bulbs, we recommend fertilizer application in the late fall. As a rule of thumb, don't apply liquid fertilizer when it's rainy or stormy out or a granular fertilizer when it's windy.
Q. Can I tell if my soil is deficient without a soil test?
A. There's no accurate way of knowing what nutrients your soil is deficient in without a test. However, a sign that your plants are lacking phosphorus is stunted growth. A clue that they may be lacking potassium is yellowing leaves. Again, these are just signs, and we recommend a soil test to match the right fertilizer to your plants.
Garden fertilizers we recommend
Best of the best: Osmocote Flower and Vegetable Smart-Release Plant Food
Our take: A low-maintenance, high-quality granular fertilizer for veggies and perennials.
What we like: Osmocote's smart-release feature feeds plants for four months, which means less application on your part. It also strengthens roots and promotes vibrant blooms.
What we dislike: Nothing.
Best bang for your buck: Miracle-Gro All-Purpose Plant Food
Our take: A classic but cheap all-around fertilizer to feed your entire garden.
What we like: A concentrated powder that mixes easily with water and produces time-tested results. Won't burn plants if used as directed. Improvements noticeable with recommended application of every one to two weeks.
What we dislike: May be too harsh for delicate plants like herbs and seedlings.
Our take: An organic liquid fertilizer that's best for shrubs and large plants.
What we like: Rave reviews for fast results, especially for lusher foliage. Much safer for plants than other brands and won't burn. Concentrate is economical.
What we dislike: Because this fertilizer is fish-emulsion based, it smells fishy and is recommended for outdoor use only.
Ana Sanchez is a writer for BestReviews. BestReviews is a product review company with a singular mission: to help simplify your purchasing decisions and save you time and money. BestReviews never accepts free products from manufacturers and purchases every product it reviews with its own funds.
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