My garden consists of seven or eight beds, inhabited mainly by perennials and bulbs.
Here is a description by Eleanor Perényi (in her book Green Thoughts: a writer in the garden) of what was necessary to maintain the classic English herbaceous border*:
For a start, it was double-dug to a depth of several feet, then filled with well-rotted manure, ashes, sand, etc., and as if that weren’t enough for a lifetime, it was taken apart every third year, dug over, replenished with huge amounts of fertilizer and fresh soil. At that point, new plants were put in, old ones in need of dividing were broken up and reset, and the whole elaborate complex reassembled.
*A perennial border. Herbaceous plants are those whose top growth dies down in the winter.
If I managed to do even an approximation of this, my perennial beds would no doubt be glorious. Deep digging would remove the mat of feeding roots put out by the Norway maples that shade the beds. All the extra fertilizer would mean those roots would return, but a three year renewal cycle would ensure reasonably root-free soil for the perennials.
When should this operation be carried out? I suspect early autumn would be the best time. Many perennials would be at the end of their blooming seasons, and all spring bulbs would be dormant. There would be enough good weather left for plants to re-establish before winter. But what about those dormant bulbs? I can tell a daffodil bulb from a tulip or crocus, but unless there was a detailed and up to date map of the bed, or excellent labels (both unlikely at my place) it would be impossible to know which varieties they were. So much for any carefully worked out colour schemes.
So am I planning to dig up my beds any time soon? Not on your life.
For one thing, I’m not Superwoman (or Super-Gardener, for that matter). Digging up tree roots–or more likely sawing and chopping them–is brutal work. I’ve done it in small areas when moving or dividing plants. I can’t imagine working over an entire bed. My beds are up to 5 feet by 20. The grand gardens of England had small armies of gardeners to do stuff like this. In this non-grand garden of Canada, there’s just one gardener–me. Yes, there are a lot of spades-for-hire in the form of landscaping and yard maintenance companies, but they seem to fall into two groups: the mow the grass and trim the edges crews, or the ones that install instant gardens around new houses built on lots where old gardens have been stripped away to make room for the new. I’d rather not deal with them.
Another problem is my beds aren’t exclusively herbaceous. Some include shrubs, which would be impossible to dig up and replace. I would have to work around them, which would further complicate matters.
And yet, just reading the paragraph I quoted above, and imagining how the renewed beds would look, and how the plants would burgeon forth and bloom the following spring and summer–that brings on an intense bout of gardener’s guilt.
My practice is to apply an annual mulch of compost enriched with a variety of organic supplements such as alfalfa pellets, aged manure, kelp meal, bone meal, or soy meal, and inorganics like lime and all-purpose fertilizer. When I plant something new, I dig up the immediate area to the depth of the spade (about a foot, maybe 18 inches) and add compost and whatever of the other goodies I happen to have on hand. And of course I cut and remove any tree roots that have invaded the spot since it was last dug. (This is why I know I could never renew a whole bed at once; a 2 x 2 foot area is an all-day project.)
The above-quoted Ms. Perényi goes on to endorse this practice in her chapter on perennials, where she offers her thoughts based on experience in her own Connecticut garden.
Nor is it necessary to double-dig. Ordinary digging in of natural fertilizer at the start, and liberal additions of enriched compost after that, are perfectly adequate.
It’s reassuring when another gardener, especially a noteworthy one, says it’s okay to do things the way one already does them. And gardening should be a life-enriching activity, not ache-inducing, heavy labour.