Charlotte Pemberton
Why No-Dig Suits A Perennial Patch
Most no-dig advice is aimed at annual vegetables — carrots, salads, brassicas — where you clear the bed and start again each season. Perennials are a different proposition, and in many ways they are the perfect fit for the method. Once rhubarb, asparagus and a good clump of herbs are in the ground, they want to be left alone. Digging around them each spring does far more harm than good, slicing through crowns and root systems that took years to build.
There is also the question of effort. A perennial bed is a long-term investment. If you spend a weekend smothering grass with cardboard and heaping on compost, you are buying yourself years of low-maintenance cropping instead of a yearly battle with weeds. The soil life does the rest: worms pull the compost down, fungal networks establish, and the structure improves without a fork ever breaking the surface.
Choosing The Right Spot
Perennials are permanent, so the siting decision matters more than it does for a row of lettuces. Get this wrong and you will be digging them up again in two years, which rather defeats the object.
- Sun: aim for six hours or more in summer. Rhubarb will tolerate a little shade, and mint actively prefers it, but asparagus and woody herbs such as rosemary and thyme sulk in gloom.
- Drainage: asparagus crowns rot in waterlogged ground. If your soil is heavy clay, build the bed up rather than sinking it in, and consider a slight ridge along the row.
- Size: a bed of roughly 1.2m by 3m gives you room for three rhubarb crowns, a short asparagus row and a cluster of herbs. Wider than 1.2m and you will not reach the middle without treading on the bed.
- Access: leave a mown path or a bark mulch strip around the edge. You will be harvesting in wet weather, and a permanent bed needs a permanent route to it.
If the ground is infested with couch grass, bindweed or docks, do not simply lay cardboard over it and hope. Cut everything back hard, then mow or strim repeatedly for a few weeks before you start, and use a double layer of cardboard. Those roots will find a gap.
Gathering Your Materials
You need less than you think, but you do need it all in one place before you begin. Nothing is more irritating than running out of compost halfway across a bed.
- Cardboard: plain brown, unwaxed, with tape, staples and plastic windows removed. Flattened removal boxes are ideal. You want enough to overlap by 15–20cm in every direction.
- Compost: roughly a barrowload per square metre, so about 10–15cm depth across the finished bed. Homemade sieved compost, well-rotted manure or a bought soil conditioner all work.
- Mulch: a 5cm topping of bark chip, straw or spent mushroom compost to keep the surface dark and discourage weed seeds.
- Water: a full watering can or a hose on a gentle setting. Dry cardboard repels water; soaked cardboard wicks it down.
Building The Bed, Layer By Layer
Start by strimming the grass or weeds as short as you can. Do not dig, and do not strip the turf — the roots and thatch underneath will rot down and feed the bed.
Lay the cardboard directly on the cut growth, overlapping the edges generously and extending it 30cm beyond where you intend to plant. Water it thoroughly as you go; it should darken and soften. Then tip on your compost in a level layer, aiming for a consistent 10–15cm across the whole area. Top with your chosen mulch. If you are building in autumn, leave it to settle over winter — worms will work the compost into the soil beneath, and the cardboard will be largely gone by spring.
Planting Rhubarb, Asparagus And Herbs
Plant through the mulch layer rather than turning it in. Push the mulch aside, cut a cross or a small hole in any remaining cardboard, and settle the plant into the compost below, firming it gently.
- Rhubarb: space crowns about 90cm apart, setting the bud just at the surface. Do not pull any stems in the first year — let the plant build strength. From year two, harvest from April to July and stop, so it can recover.
- Asparagus: buy one-year-old crowns and set them 45cm apart in a row, spreading the roots out. It takes three years before you cut a proper spear, so be patient and keep the bed weeded. Harvest for six weeks only once established.
- Herbs: rosemary, sage, thyme and oregano all appreciate the sharp drainage of a raised, mulched bed. Chives and lovage prefer richer ground. Keep mint in a sunken pot with the rim just above soil level, or it will colonise the lot.
Keeping It Going With Almost No Work
Each autumn, add another 3–5cm of compost to the surface and top up the mulch. That single job replaces feeding, forking and most weeding. Cut back herb stems in spring rather than autumn where you can, as the old growth shelters wildlife over winter and protects the crowns.
Watch for slugs on new shoots in a wet spring, and keep an eye out for asparagus beetle in June — pick off the grey adults and any larvae you spot. Beyond that, the bed largely looks after itself. A no-dig perennial patch rewards patience rather than effort: build it once, keep the surface covered, and it will crop for a decade or more.
