13 Apr 2010

How To Read A Fertilizer Label

Down To earth Multi-Purpose Fertilizer
A balanced, multi-purpose fertilizer

Every gardener has seen the three big numbers on the front of a fertilizer bag or box.

Most know what the numbers stand for (in order): Nitrogen – Phosphorus – Potassium, also known as N-P-K.

These ingredients are always listed in this same order.

The higher the number, the higher the water-soluble percentage of that ingredient in the fertilizer. For instance, Sulphate of Ammonia, rated at 21-0-0, is 21% soluble nitrogen. It contains no potassium or phosphorus.  On the other hand, something like SuperPhosphate, rated at 0-20-0 contains 20% phosphorus but no nitrogen or potassium.

Why should we care specifically about these three elements over all others? What exactly do they do?

  • Nitrogen promotes green growth above the soil.
  • Phosphorus promotes flowering, blooming, and root growth
  • Potassium promotes general vigor with compact, robust growth.

These attributes are sometimes learned by the memory aid, “Up, Down, All-Around.”


So do higher numbers equal better fertilizers?


Healthy plants grow in healthy soil.

fertilizer burn
Fertilizer Burn

Soil amendments and fertilizers certainly play a role – sometimes the crucial role – in promoting plant growth. But highly soluble, super-concentrated ferilizers can actually harm plants, the soil, soil microbes, and the environment.

Fast release nitrogen can burn seedlings. You’ve probably seen plants with brown edges on their leaves. That can be a sign of fertilizer burn.

Further, highly soluable fertilizers wash through the soil quickly, leaving little or no nutrients behind for continued growth.

And finally, high concentrations of phosphorus run-off can pollute water and kill fish.


While N-P-K gets all the glory on the label, other ingredients, such as minerals and trace elements are just as important to the health of your plants. Use the Big Three numbers on the front of the bag as a guide.

Then turn the bag or box over and look at the rest of the ingredients. A long list of nothing but unpronouncable chemicals is unlikely to promote a healthy environment. On the other hand, trace minerals and other insoluble elements will bind with the organic matter in your soil. They are unlikely to wash out as quickly, and so may slowly release nutrients to your plants throughout the growing season.


compost worms
Nature's Perfect Gardeners

Soil rich in organic matter will also be rich in life – most clearly illustrated by the presence of earthworms. Burning, quick release fertilizers kill worms, leaving you with dead soil that demands constant re-fertilization. Compost and minerals, in contrast, provide food for the worms, who turn it into one of nature’s richest fertilizers: worm castings.

Organic fertilizers tend to have “lower numbers” than chemical fertilizers, in part because organics are less water soluble. And yet, that very fact gives them an edge in promoting sturdy, compact plants with deep roots – plants more able to resist insects and disease.


Do you have to be 100% organic to have a healthy garden? No, of course not.

But you’ll find that shifting your focus to organics will, over time, build healthier soil. As your soil improves, your plants will improve. You’ll be less tempted to reach for pesticides, and the beneficial insect population will be able to do its part in keeping insect damage down.

15 Jul 2008

Our Commitment to the Environment

At Plantscapes, plants are not just our job, they are our passion.

Because we love nature, we care about  the environment. Several Plantscapes employees are members of their local Master Gardeners and Master Composters groups. Some belong to Plant Amnesty or Seattle Tilth.

This personal commitment to environmentally sound landscaping carries through from our personal to our professional lives. Plantscapes has always recycled plant material as well as paper, cardboard, and other office waste.

Beyond these common business practices, we are commited to using the safest and least disruptive methods of pest and weed control.

Strong, healthy plants are the best defense against pest infestations. We will always work with our clients to choose the right plant in the right place – one that is suited to both the light and temperature requirements of the individual environment where it will be placed. When plants outgrow their space or containers, we replace them.

However, even with the best of care, some pest problems are inevitable (that is part of the cycle of nature). When problems arise, Plantscapes is committed to using the softest pest control methods available.

For instance, Plantscapes has been a leader in the use of beneficial insects for pest control in shopping mall, hotel, and business atriums.  We use soaps and natural pest control products to keep plants healthy.  If there is any chance that the public could unknowingly be exposed to chemicals, we choose organic pest control methods instead.