Category: Environment

Fertilizer is probably something all gardeners use, at least from time to time.  It comes in many forms from chemical to animal manure, or perhaps homemade in the form of ‘tea’ made from compost, manure or green plants.  There are also fertilizers claiming to be organic.  Some are added to the ground, and others applied to the leaves of the plants (foliar feeding).  Some are strong and others weak.  Of course there are also the component parts; nitrogen, phosphorus and potassium (N,P and K), and fertilizers are given numerical ratings of these components like 10-20-10.  It can all seem confusing and opaque, especially at the beginning.

In particular many people feel somehow that fertilizer is an important element of gardening, and since other people use it, they have to as well.  An extension to this is the knowledge that organic gardeners don’t use chemical fertilizers, therefore you have to find an organic alternative like manure.

The Habit

This feeling like fertilizer is somehow an important part of gardening, can lead to a sort of addiction or dependence on fertilizer, that works something like this.

First you add fertilizer to your garden and you notice everything grows faster and looks greener and healthier.  This is particularly true with fertilizer high in nitrogen, and it’s very easy to get the feeling that if some fertilizer makes the plants look so good, more must be better.

At this point you might give your plants so much they experience sudden death, but more likely you keep giving them small amounts over time, perhaps a little extra when you sense it’s needed.  Since fertilizers usually contain more than one nutrient (NPK), probably over time the nutrients in your garden are getting more and more out of balance.  Since this probably leads to your plants not growing well, it can easily make you think you need more fertilizer.

By the time you’ve added so much that you finally realize you are causing the problem and not solving it, you can be faced with a situation that’s very difficult to deal with.

As someone who has spent the past decade or so moving their garden around, and needing to borrow spots from other people, I can tell you it’s a very common problem in my area.

A related problem can be if your garden is former pasture land, or otherwise has a lot of recently applied animal manure.

When do you need fertilizer?

As a rule, for most people, a well managed and established garden does not need any fertilizer.  It’s too complicated a topic to make such a broad statement, but this is the general rule.

It’s possible when you first start a garden you will have some problems, usually a shortage of organic material.  In this case it’s likely you will have to do something about the existing problems, and this might involve using some fertilizer.  Often fertilizer is not necessary, but sometimes it is.

If you are unable to practice good principles of crop rotation, you may need some fertilizer to compensate.  It’s worth pointing out you’ll likely end up with a whole host of other problems too if you don’t practice proper rotations.

Potted plants often require fertilizer.

Unless you are sure you need fertilizer, it’s best not to use any at all.  If you do need to use it, it’s best to use something weak like fish emulsion or homemade teas from green leaves or compost.  Fresh animal manure should almost never be used in your garden, rather it should be composted first.

If you live somewhere soil tests are available, get an analysis of your ground before you add any fertilizer.  This will give you an idea if anything is needed.

What can you do once the damage is done?

Besides hoping for rain, and just waiting for it all to wash away, one of the first things you should try to address in over-fertilized ground is nitrogen (N) levels.  Too much nitrogen, and your plants will be stressed and the weeds will grow faster than anything else you may try to grow.  Not enough, and your plants will be weak and small.

In my experience, the problem manifests itself like this.  In a healthy garden nitrogen fixing plants are the primary source of nitrogen, and the ground will be rich in fixed nitrogen.  Another much less important source of fixed nitrogen is compost.  Fixed nitrogen remains in the ground, and tends to become available when as the plants need it.  Any other source of nitrogen that gets added to the garden, whether from natural sources like manure or chemical fertilizer, will be soluble.  Soluble nitrogen is available immediately, and can stress or kill plants.  Soluble nitrogen can wash away, but it can also accumulate in large amounts in the ground.  In the presence of soluble nitrogen, nitrogen fixing plants will fix less, so there will be less fixed nitrogen in the ground.  In addition, if your ground is low in organic material, it may not have the capability to retain fixed nitrogen.

If your ground has too much soluble nitrogen, for example has a lot of animal manure added, try covering the garden with a high carbon mulch material like wood chips or straw.  In extreme cases you may want to mix a small amount of this material into the ground, but this can cause other problems as well, so don’t do it unless you think it’s really needed.  High carbon material will remove nitrogen from the ground.

If your garden is lacking nitrogen, consider a weak nitrogen fertilizer like fish/kelp emulsion, or homemade fertilizers like ‘teas’ in the short run, but nitrogen fixing plants are key to the long term.  Consider planting one or more nitrogen fixing trees like Alders or Sea Buckthorn in temperate climates.  For other climates you’ll have to research the issue and see what’s available.  Growing nitrogen fixing crops like beans and peas is also a good solution, perhaps as companion plants.  This is a situation that may take a few years to get stabilized, and if you’re using a chemical fertilizer now and intend to stop, you may want to cut back as a first step, for just this reason.

For other nutrient imbalances, I don’t have any good suggestions.  If you are unsure of the state of your ground, adding compost is always a safe thing to do.  If you can, let your ground lay fallow for a year or more before using it again as a garden.

Marc at Garden Desk made a couple of posts recently about his tomato growing plans for next year, and in the process some interesting points came up, not only in the posts themselves but in the discussion too.

In my last post I said if you asked 100 gardeners for advice, you would get 100 different answers.  I think the same must be true if you asked 100 different gardeners what their gardening goals were.

Imagine how boring the world would be if we were all white males of European decent!  By the same token, imagine what it would be like if all gardeners had exactly the same goals in mind.  As a gardening community, and as a world, we are much stronger because of our differences and our different goals.

Some people make a living growing food and raising animals, and most of these people are committed to the idea they are providing an important service to the world.  In this case they are concerned about finances, as well as producing usable food that people want to buy, in the largest quantities possible.

Some people are plant breeders, who are concerned with finding the perfect combination of genes, and discarding everything that’s not quite there yet, wherever ‘there’ is.

Still others are home gardeners like Marc who loves tomatoes, in particular loves to see the differences in strange heirloom varieties and seeks goals like the earliest fruit or the tallest plants.

If you ask any of these people for advice, they will offer it from their own perspectives, and it will all be a little different.

Zero Air Miles

If you buy food from the store or market, it comes from somewhere.  It has to be transported, often from great distances.  It will generally have been produced with chemical and energy inputs, as well as someone else’s labor.  If you throw half of it away, this is really wasteful.  Literally, you are wasting food that could be used to feed hungry people or just not produced in a wasteful way in the first place.

Assuming you’re an organic gardener, the only thing wasted if you throw something away you grew yourself is a bit of sunshine and your own time!

The most important goals for your garden have to be the ones you set for yourself.  If it weren’t for your own goals, there wouldn’t be any point in having a garden in the first place.  Whatever those goals are, feeding yourself or others, seed saving, plant breeding or just enjoying nature and biodiversity, this has to be your top priority in any garden.

Don’t let anyone tell you you are doing something wrong in your own garden!  At the same time, don’t be immune to input from others, because there’s lots of good information out there, especially for people just getting started.  It can really save you a lot of time by not making the same mistakes others already have.

Inputs and Outputs

While you’re enjoying yourself and pursuing your goals, give some thought to what you’re doing.  A garden really needs very few inputs.

If you set up a garden with new wood that comes from cleared land, is milled and transported, that’s really a huge resource you are using unnecessarily.  It’s expensive too.  Consider using used materials in your garden, like stones or bricks, or recycled wood.  Stones and bricks will last longer than wood too, which can be very useful.

The same is true with peat products.  While it’s true they are a renewable resource, they are generally not mined in a sustainable way and often have to be transported long distances.  If you live next to a peat bog, this is one thing, but otherwise as an alternative to peat products consider getting compost made from municipal (council) waste which is available in many areas, or better yet making your own compost.  Consider why you think you need peat in the first place, because it’s rarely necessary for use in the garden.  Peat is useful for indoor plants or starting seeds, because it is weed free and sterile.  It can also be useful for outdoor potted plants, because local soils are sometimes not well suited for this.  Since your garden is neither sterile or weed free, there are usually better and cheaper alternatives to peat.

Don’t be fooled by peat free alternatives either, like coir, which also have to be milled and transported long distances!  These are generally as wasteful as peat, and usually more expensive.

Consider most chemicals and fertilizers are also very wasteful as well as almost always unnecessary.  Almost everyone’s garden will do fine if you rotate your crops, make and use your own compost, and grow nitrogen fixing plants from time to time.

Consider collecting rainwater from the roofs of structures near you garden, perhaps your own house.  Perhaps collecting grey water from your house is an option.  Perhaps you have other renewable sources of water nearby.

While tempting to the beginning gardener, power tools like tillers are not usually very useful.  Consider getting one used, borrowing or renting one, until you are really sure it’s needed.  Non-electric power tools use an astonishing amount of fuel, often as much as a car, and in some US cities cause 15% of the air pollution.  Consider using something electric, or sticking to hand tools.

Finally, if you do end up with extra food that’s usable, consider ensuring it gets used.  Process and store it for later use, or give it away.  If you do throw it away, you aren’t hurting anyone or anything, but you can only do good by making sure it’s used somehow.