Create A School Garden With Containers
One of the most significant challenges of urban agriculture in the classroom is finding a large permanent space. But what if there was a solution that means that your area need not be large or permanent? One of the easiest ways to introduce urban agriculture and gardening in the classroom is with containers. Small, attractive, and portable, container gardening might be the perfect way to gets your hands dirty without breaking the bank or going all-in with a fixed garden site.
What to Grow?
What you grow is entirely up to you and your class. With the right container, soil, water, and lighting, you can grow a staggering variety of plants.
Herbs and Leafy Green
When it comes to growing food in containers, herbs and leafy greens like basil, mint, rosemary, lettuce, and spinach are good choices. If possible, choose long-lived perennial varieties that you can harvest on an ongoing basis. Before deciding which plants you want to grow, consider how you might use them as a class or school.
If you have larger containers and lots of light, consider fruiting plants like tomatoes, peppers, cucumbers, peas, and beans. With even larger containers consider small trees or shrubs like citrus or figs.
Choosing Soil For Your Container Garden
Choosing suitable soil for your container is probably the most critical step. Though, you might be tempted to grab a few shovel scoops of soil from the garden resist the urge. While garden soil works well in the backyard it’s a terrible choice for containers; more often than not it will pack into a tight brick and be utterly unusable.
Technically speaking soil is composed of organic matter, water, air, and inorganic minerals such as sand, clay, or silt. It’s these inorganic minerals that tend to compact and make garden soil a poor potting mix. Instead, choose a soilless potting mix. While soilless potting mixes are chalked full of organic matter, water, and air, they lack the inorganic minerals found in actual soil; hence the term “soilless”. However, with more room for water and air, soilless mixes are lighter, stay fluffy (filled with air), and don’t easily compact.
Watering Your Container Garden
While each variety of plant has its preference for moisture, the key to a healthy container garden is to find a happy medium between soggy soil and bone dry. Generally speaking, your growing medium should be slightly damp to the touch but not wet. If you could grab a handful of soil, squeeze it, and get a single drop of water, you’ve got it right.
How frequently you water will depend on the size of your pot, its location, and the plant you’re growing (some plants, like tomatoes, are thirsty and won’t tolerate drying out).
To prevent overwatering, use containers with drainage holes at their base. While you can get around a lack of drainage holes by adding stones (or some other porous medium) to the bottom of your containers your plants will be better off if excess moisture can freely drain through the bottom. Remember that air is a critical component of healthy soil and that over-watering removed air to the point that the plant’s roots will be unable to breathe.
Lighting Your Container Garden
Like water, each plant has its preference for how much light it wants. While tomatoes and peppers love the sun other crops like lettuce, spinach, and broccoli are more shade tolerant. Depending on the location of your container and what you’re growing, you may get away with a sunny South-facing window or need to supplement your crop with full-spectrum artificial lighting (such as these sunblaster compact fluorescents or T5s.
Choosing The Right Container For The Job
Typical, Off the Shelf, Pots
There’s nothing standard about an off the shelf pot as each pot is sure to vary in height, depth, shape, size, and material. Plastic containers are inexpensive and light but not as durable. In contrast, ceramic pots can be expensive and bulky. The best pot for a school is probably a free pot so talk to colleagues, big-box stores, and nurseries to see if you can take any old containers they might have laying around. Plastic nursery pots inexpensive, pleasant to work with, and a good choice for school; they’re not pretty, but they’re durable and in abundance.
A self-watering pot is exactly what it sounds like – a pot that waters itself. Though not foolproof, self-watering containers generally have a water reservoir below the soil and a wick to draw water into the container as the soil requires it. Any form or self-watering pot or automatic watering technique is valuable for schools because it answers the existential questions of “who will take care of the plants over the weekend or break?” You can sometimes find self-watering pots at garden supply stores, though, they’re not as common.
An Earthbox is a complete gardening kit and commonly used by the Sustinable Food Edmonton’s Little Green Thumbs Program to grow vegetables and herbs in hundreds of school classrooms. The basic Earthbox kit consists of a self-watering grow box, casters (for easy transport), and an organic soil amendment (fertilisers and minerals). You can purchase lights as an accessory.
Earthboxes provide roughly two square feet of growing space on top of a self-watering reservoir; keep the water reservoir topped up, and the innovative Earthbox design wicks up water when needed. I can say from personal experience that growing in Earthboxes is an easy and efficient way to start growing food in the classroom. The only downside of Earthboxes is that they are one of the more expensive options.
For the DIY class and teacher, making Global Buckets might be the perfect option. The invention of two high school students looking for an inexpensive way to make Earthboxes, a Global Buckets is simply a bucket inside of another bucket. By adding a wick (cloth or soil filled pot) and a watering tube, you can build an inexpensive self-watering container for a fraction of the price of an Earthbox. Though, not at pretty, a Global Buckets are deep enough to root vegetables like potatoes or grow larger plants like small trees and shrubs.
Scaling Up Your School Container Garden
The great thing about a container garden is that it scales so effortlessly; you can start with one container and scale up (or down) as you see fit and as the school year progresses. However, should that day come that you’d like something more substantial and permanent, raised beds are a logical next step.
What is a raised bed if not a large pot? While a raised bed is large to be virtually immobile, they’re a logical next step for a classroom looking to scale up from or consolidate smaller container gardens. The trick to a successful raised bed on school property is finding a suitable site; ideally with plenty of sunlight, access to water, accessible to the students and staff, and relatively permanent (they’re difficult to move).
There are many off-the-shelf raised bed options or kits, though, if your school is fortunate enough to have an industrial arts class it might be possible to turn your raised bed into a fabrication project. A few things to consider; avoid using anything wider than two-arms-lengths or you’ll have to crawl into the garden to access vegetables growing in its centre (note: use your student’s arms as they’ll be the ones planting and harvesting), choose a light and fluffy soil or soilless mix. You don’t have to build it too deep, though, I’d recommend at least a foot. Organic matter helps retain moisture to the more you have in your soil, the better.
Self-Watering (Wicking) Beds
If you built a raised bed on top of a source of water you’d have a wicking-bed. Wicking beds are large self-watering pots. While there are a lot of ways to achieve this, most wicking beds rely on creating a watertight reservoir, filling it with gravel, covering the gravel with landscape fabric, and building a typical raised bed on top. Like self-watering pots, wicking beds use the soil’s natural water-wicking action to soak up water as needed.
As a less technical alternative, I have used 4″ perforated pipe to bring water from the downspout of a building directly under your garden. I prefer this technique as it doesn’t require building a water-tight reservoir or moving heavy gravel.
There are some excellent online resources for both of these wicking bed techniques.
To Sum Up
However you decide to do it, containers gardening is an excellent way to start growing food in the classroom. Use a light, soilless growing medium in inexpensive (or free) container, and you’ll be on your way! Start with a single pot and scale up as you find success.