I have a school which has a 4′ x 8′ area and the teacher wanted some guidelines.
Soil – I prefer the SLC Raised Bed Mix. It’s more expensive, but makes it very easy to plant. You should only need one cubic yard. Get a parent with a pickup truck to get the mix. I have had poorer results with other soil mixes.
http://stlcompost.com/soil/
Some YouYube videos just use compost to plant in. The problem I have with the compost I buy is that it is still very hot and may burn seeds and new plants. It certainly burned and killed my grass where I had it dumped one year.
You can buy cheaper soil mix, but in a couple of years this soil compacts down and it’s very hard for the young kids to dig in when planting.
Mulch – The mulch I like is called Black Forest Mulch. It’s a combination of fine mulch and compost.
You can buy it at Lowes or at St. Louis Compost.
http://stlcompost.com/by-the-bag/
I prefer to use compost as a mulch.
Construction – Gateway Greening has a good PDF on the materials and construction of the bed. They use a treated wood which they believe is safe. You may want to use cedar if your are going to raise vegetables and want an extra layer of security. Here is another good article by the U. of Missouri about raised beds and their materials.
Edging – If you can afford it, it’s nice to edge the bed with pavers. It not only makes the garden look more professional, but keeps the grass away from the garden. The kids will be walking around the garden a lot and it will prevent the area from getting muddy. Here’s a garden done by one Boy Scout with pavers.
Fertilizer – The first year you might not need fertilizer, but you can add some later in the year if plants look like they might need some help. I usually add two inches of compost every year to feed the soil.
Water – It’s imperative that you have a source of water nearby. You may need a special key to turn the water on. You can buy those at a hardware store. Talk to the maintenance people for help. I also like to leave a short hose by the garden so that it’s easy to water. You will find that during the summer that the raised bed will need more water.
Maintenance – Schedule parents/families/scouts to maintain and water the garden during the summer. Once a week should be fine. Weeding and watering are the main chores.
Size – while 4′ x 8′ is a standard, it might be a bit big for kids. You may want to try 3′ x 8′.
Other Tips
- Make sure the kids can walk all the way around the garden. They will need to be able to plant and pull weeds without getting in the garden.
- You want most of your plants to be blooming in September. This is when the kids will be coming back to school and the Monarchs will be migrating.
- Find a location with the most sunshine possible.
- Make sure the small plants are in the front where they will get the most sun. You don’t want the tall plants to shadow the smaller plants.
Here is a general idea of what I might plant.
I’ve divided it into three areas – Tall – Medium and Small.
Tall
Dill, Fennel, Milkweed, Agastache, Blazing Star, Zinnia-tall, Verbena bonareinsis
Medium
Shasta Daisy, Salvia, Maltese Cross, Echinacea, Lantana, Coreopsis lanceolata, Zizia,
Small
Parsley, Allium, Pussy Toes, Coreopis (small), Zinnia -Profusion
Butterfly Gardening 