Heidi Heiland's Fertilizer 101

4:46 PM, Jun 12, 2013   |    comments
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GOLDEN VALLEY, Minn. -- Plants have begun to grow, and homeowners are wondering if they should be fertilizing their gardens. Heidi Heilland, Certified Professional and owner of Heidi's Lifestyle Gardens, is here to discuss fertilizers and fertilizing.

Garden plants use nutrients when they are actively growing leaves, stems, roots, blooms, and fruits. Spring is a great time to give your gardens the fertilizer boost that will reward you with strong, healthy plants covered in blooms.

What are fertilizers? Fertilizers are essential elements that plants require to grow normally.

Fertilizers are grouped generally by the degree to which a deficiency will limit a plant's growth, and the quantity of each nutrient that plants typically pull from the soil. 

Primary Macronutrients (Nitrogen, Phosphorus, Potassium)
Large consumption and depletion will easily limit plant growth
Secondary Macronutrients (Calcium, Magnesium, Sulfur)
Relatively large consumption but readily available in soil and rarely depleted 
Micronutrients (Copper, Iron, Manganese, Nickel, Zinc, and others)
Low consumption but readily available in soil and rarely depleted

The three primary macronutrients, N(nitrogen) - P(phosphorus) - K(potassium), promote plant health in three different ways:

N - nitrogen: promotes the growth of leaves and vegetation, aids chlorophyll production 
P - phosphorus: promotes root and flower growth, aids energy conversion
K - potassium: promotes strong healthy plant tissues, aids plant metabolism and water pressure

The many secondary macronutrients and micronutrients are readily accessible by plants in gardens. Plants in containers do not have access to these secondary nutrients and benefit from fertilizers that clearly state "Micronutrient" content on the label.

Fertilizing Containers
Water soluble fertilizer with micronutrient: 20-20-20 (ex: Miracle-Gro)
Fast acting, immediately usable by plants, used repeatedly throughout the growing season, applied with hose end sprayers as a foliar spray or with watering cans as a soil drench.
Slow release fertilizer with micronutrient: 14-14-14 (ex: Osmocote)
Slow acting, made in 4 month, 6 month, and 9 month release durations, takes time to start seeing results, typically worked into the potting mix before planting.

Fertilizing Gardens
Because soils vary from location to location we recommend sending the U of MN a soil sample for testing. It is a common misconception that 'if some is good, more must be better'. Fertilizer applied at the wrong rates can do more harm than good.

Building good soil structure with the addition of organic humus such as compost and leaf litter will often yield healthier plants than blindly applying granular fertilizers. It also helps buffer pH which makes existing soil nutrients available to the plants, and introduces beneficial microbes that create thriving relationships between plant roots and the soil they are growing in. Compost is best mixed thoroughly throughout the soil in new gardens, but can be top-dressed into existing gardens by scratching it in and around plant roots and turning it by the shovelful into the soil between plants.

Garden plants can also benefit from a water soluble fertilizer applied as a foliar spray with a hose end sprayer. Plants can absorb nutrients through their leaf surfaces up to 20 times more efficiently than through their roots, yielding impressive results quickly. Foliar sprays are independent of soil content, and are best applied at key lifecycle points including rapid growth periods, at the beginning of bloom periods, and just after fruits set and begin to enlarge.

So remember, more is not better but most plants appreciate being fed. So go to your local garden center to purchase what works best for your gardenscape and Bloom On!

(Copyright 2013 by KARE. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed. )

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