Good Compost for Square Foot Vegetable Gardening

(Question)

I have started a “square foot garden”, using soil comprised of 1/3 peat moss, 1/3 vermiculite and 1/3 compost. This is a well researched approach, and experts suggest mixing compost from 5 different sources to get a well-rounded product (eg, 1 from composted manure, one from mushroom compost, one from sea plant compost, etc.). I have difficulty finding different varieties in Toronto, and I think I saw the results in variable produce from the same plantings in containers with different composts. It is also a lot of work and requires a lot of space to mix large quantities of 5 types! Can you suggest a place or type of place that would have reliable, well-rounded compost? Would a country garden store that sells it in bulk be better?

Assume that my irrigation system, sun exposure and climate are all pretty good.

If not, can you suggest a resource for a simple approach to dressing various vegetables over the course of the growing season? I am an experienced gardener, but fairly new to vegetables and overwhelmed with the variety of suggestions for fertilizers, combos, brands, timing, code-names for different types, etc. Hoping a really good compost can solve many of these problems.

Thanks for any suggestions you may have.

(Answer)

Raised bed vegetable garden is gaining in popularity for many good reasons, and the square foot method is a terrific way to organize your plantings for a bountiful harvest.  The very specific approach to mixing the growing medium that the author of the popular square foot method advises may indeed not be practical for everyone, especially for those of us living in small urban spaces, even if we could find all the required ingredients available separately.  As you mention, there is a huge amount of information out there with every gardening blogger weighing in with a favourite soil mix, a favourite type of compost, a favourite fertilizer.

A simple approach to soil should work for your raised bed.  In a Toronto Star article, garden writer Mark Cullen discusses Canadian author Tara Nolan’s book, Raised Bed Revolution,  https://markcullen.com/library/raised-in-a-bed/ and recommends simply “the best quality, weed free soil that you can get your hands on…Quality triple mix works well also.”

In his recent books, Get Growing and Food to Grow, (readily available at the library) Toronto-based garden writer Frankie Flowers makes some simple recommendations for fertilizing and for the addition of compost: https://www.frankieflowers.com/home-garden-grow-what-you-eat  You should be confident in using the same type of fertilizer formulation and compost for all the vegetables you plan to grow.

There is satisfaction in creating your own mix, to be sure, such as you’ve already done.  Here is a post offering a couple of recipes for soil mix (raised beds) or soilless mix (containers) with a fertilizer component included, as well as some general guidelines on container and raised bed gardening:  https://www.extension.purdue.edu/new/ho-200.pdf

The Toronto Master Gardeners, in partnership with the City of Toronto, has produced this guide to organic vegetable gardening, in which we recommend any soils or composts from reputable garden centres:  https://torontomastergardeners.ca/wp-content/uploads/2012/07/Organic-Vegetable-Gardening.pdf . Mulching is a helpful practice in raised beds where we want to conserve moisture and avoid weed growth.  Here is a Toronto Master Gardeners guide which you may find useful:  https://torontomastergardeners.ca/wp-content/uploads/2012/07/Using-Mulch.pdf

Reputable brands of composted manure – cow or sheep (as you’ve likely read, many experts have their personal preferences) – and more recently, mushroom compost, and – new to me, shrimp compost – should be available in bags from major garden centres.  Hen compost is available in two-litre cartons.  The Government of Canada regulates compost content and quality under the Fertilizers Act.  A country store or garden centre selling finished compost in bulk may compete well with the bagged variety in terms of price.  Here is a brief guide to selecting commercial compost – there are some photos that show partially and fully composted material that may be useful if you choose a bulk supplier:  https://www.extension.umn.edu/garden/landscaping/implement/compost.html

Very best of luck with your raised beds.  Whichever of the many possible soil routes you choose, with good organic additions in the form of compost, and fertilizer should you think it necessary, you should be assured of a satisfying harvest.