Container Gardening

One of the biggest advantages to container gardening is the level of absolute control you have over your soil conditions.

If you are planting in the ground, you are working on a grand scale that leaves you only a few options: accept the starting conditions you have been given and amend them through soil additives, or remove huge amounts of dirt and soil and haul in lots 0f new dirt and soil.

If you are growing vegetables in containers, on the other hand, you have complete control over what you put into the pot.  As opposed to planting vegetables that work in your garden conditions, you can create soil that is ideal for your container vegetables.

The first step is to decide what you want to plant and find the ideal conditions for growing it.  The main category you need to consider when growing vegetables in containers is the pH level of the soil.

Most vegetables like a slightly acidic soil: fortunately, most good soilless potting mixes are already slightly acidic because the peat moss which serves as a base to most of them is acidic.  If you are making your own potting mix, make sure to test the pH before planting in it.  If you balance your ingredients well, you should be fine.

Here is a basic summary of pH levels required for different vegetables.

After the soil is set up with a basic pH level, you will need to add fertilizer.  In-ground gardens can get some nutrients from the soil as-is: when growing vegetables in containers you need to be sure you are providing everything the plant needs to eat.

The easiest way to do this is to buy a complete commercial fertilizer with the correct proportions for the plants you want (10-15-10 will work fairly well for most vegetables, though you can fine-tune for flowering or leafy vegetables if you like).

If you prefer, you can use organic fertilizers, or otherwise fine-tune by adding nutrients in individual portions.

Here are a few tips to remember when working with your container vegetable garden:

1. Too much fertilizer can burn the plants.  You want to be certain to fertilize on a regular, steady schedule, following the directions on the fertilizer container.
2. If you get too much water, it can wash nutrients out of the soil.
3. Your plants are completely dependent on you for their nutrition.  If you don’t feed them, they can’t feed you.

So, you know the basics about vegetable garden fertilizer.  Now that you understand what your plants need, how can you get it to them?

If you’ve made the decision to use solely organic fertilizers, you will need to do a little mixing and matching to give your plants all the nutrients they will need.  As a caution, most organic fertilizers are not pH-neutral.  You will need to test your soil to make sure you are not making it too acidic or alkaline for your plants.  Here is a quick guide to organic fertilizers.

1. Blood Meal – Blood meal is a byproduct of the meat industry, and a good source of nitrogen for plants.  It is what it sounds like, the dried, powdered blood of animals.  It’s around 12-14% nitrogen, and can be used as a fertilizer by sprinkling it on the soil.  It will have an acidic effect on the soil.  Note: blood meal is a very fast-acting organic fertilizer, and the effects won’t last very long.  If you apply too much at once, the nitrogen can burn the plants.  Don’t overuse.

2. Bone Meal - Bone meal, like blood meal, is produced by the meat industry.  Bones are sterilized and ground up.  Bone meal has some nitrogen, but it is mainly a source for phosphorus and calcium.   Bone meal is slow-release, and should be worked into soil before planting.  You can add more once your vegetables start to set fruit for an extra boost.

3. Fish Emulsion - Fish emulsion is made from waste fish products.  It is a source of nitrogen, though it contains all three major nutrients in varied balances.  It can be very smelly, but is not as hard on plants as blood meal.  If you have tender plants, fish emulsion may be safer than blood meal.  It is fast-acting.

4. Liquid Seaweed – Liquid seaweed is a source of nitrogen and potassium, but more importantly, it contains many of the micronutrients plants need to thrive.  Regular applications will help your plants thrive.  With such low N-P-K levels, you can add it to almost every watering and not need to worry about micronutrient levels.

5. Rock Phosphate – Perhaps predictably, rock phosphate is a rock that is high in phosphorus.  Its phosphorus is not as accessible to plants as some, but this makes it useful for container gardening: it is very slow release, and can be mixed into the soil at the beginning of the season.

6. Greensand – Greensand is a kind of sand which is not green, but is a good source of potassium and micronutrients.  It also helps keep soil loose, which is useful for containers where you won’t have as many insects in the soil to aerate it.

Next to regular watering, the most important part of container gardening is fertilizing.  In the ground, plants can pull nutrients from the dirt, slowly and steadily.  A container, on the other hand, is a closed system: nothing goes in but what you put in.  This means that if you want healthy vegetable plants, you have to supply the fertilizer to keep them healthy.

So, what is fertilizer?  Fertilizer is a combination of basic nutrients and minerals which plants need to survive.  Fertilizing your plants regularly works like vitamin pills do for people: they provide balance to a diet that is almost certainly inadequate to start.

There are three main nutrients that plants need: nitrogen, phosphorus, and potassium.  A complete fertilizer will contain all three of these nutrients.  A balanced formula contains all three in equal amounts.  Depending on what you are growing, you will want different proportions of these nutrients.

Nitrogen is used by plants to build healthy foliage.  It is critical for all vegetables, but especially important in vegetable container gardens where you are focusing on leafy vegetables.  Lettuces, spinach, etc, would want a fertilizer that focuses on nitrogen.

Phosphorus is used by plants to produce healthy flowers and fruits.  Tomatoes, peppers, squash, and the like will need more phosphorus, especially when they are ready to shift from growing leaves to growing fruit.  When growing tomatoes, it can be useful to add a phosphorus booster at this stage to assist them in moving to fruiting.

Potassium helps build healthy roots in all plants.  Generally, the healthier the roots, the healthier the plant, so keeping the potassium level where it should be can prevent many plant problems.

Every commercial formula will tell you, somewhere on the packaging, what the proportion of the nutrients is to each other.  It is the proportion that matters in fertilizer, not the absolute amount: you will need to dilute fertilizer to use it.

To tell the proportion of these nutrients in a commercial fertilizer, look for a series of three numbers on the label.  This is the N-P-K number, viewed in the form 10-20-10.  The numbers represent the percentage of the fertilizer that is, respectively, nitrogen, phosphorus, and potassium.  The numbers are always written in that order.

In addition to the three major nutrients, your plants need a collection of lesser nutrients.  These include calcium, magnesium, sulfur, iron, manganese, copper, chlorine, boron, zinc, and molybdenum.  A good all-around commercial fertilizer will contain all of these in trace amounts.  If you ever find your plant struggling, and cannot tell why, applying a mix of these trace elements to your plants may help them revive.

I generally start my planting with a potting mix that comes pre-fertilized.  This means the mix has a fertilizer mixed in which is released slowly by watering.  Over the course of a few months, the plants will unlock and consume that fertilizer.  On top of that fertilizer, it’s a good idea to fertilize every week or two weeks according to the instructions on your fertilizer.

Be careful not to over-fertilize!  Many of the substances found in a standard fertilizer, including the main nutrients, can actually damage plants if overused.  Keep to the standard schedule unless your plants seem to be struggling.