How to mulch borders with bark

A mulch does three jobs at once. It blocks light to the soil surface, which stops most weed seeds germinating. It slows evaporation, so the soil underneath stays damp for longer in summer. And as it breaks down it adds organic matter, which improves the structure of the ground over a few seasons.

Bark is the usual choice for planted borders because it looks right, knits together so it does not blow about, and rots down slowly. It will not kill weeds that are already established, so those come out first. Think of it as prevention, not a cure.

The best times are spring, roughly March to April, and autumn. The point is to mulch when the soil is already moist and not frozen. Bark traps whatever is in the ground at the time, so if you lay it over bone-dry soil in July you just keep it dry.

Avoid mulching in a hard frost or over waterlogged ground. A mild, damp day after rain is ideal. Spring mulching gives you weed control and moisture through the summer, which is when it does the most good.

Landscaping bark, often sold as border bark, is the graded material most people want for flower beds and shrub borders. It is decorative and sits well around plants. This is the one TopTurf sells, at £87 per bulk bag.

Play bark is a softer, graded bark meant for under swings and climbing frames where a fall depth matters. It works in borders too but you are paying for the grading. TopTurf does not stock it, so for play areas buy from a specialist supplier.

Woodchip is the cheapest mulch some yards sell, and it is fine for informal areas, wilder beds, paths and around trees. It is coarser and rots down faster than bark, and TopTurf does not sell it. Keep fresh woodchip on the surface rather than digging it in, as buried fresh chip can lock up a little nitrogen at the soil interface.

Work out the area of your border in square metres, then pick a depth. For a general top-up, 50mm is enough. For proper weed suppression on a fresh border, go 75mm.

A bulk bag of bark is about 0.7 cubic metres. That covers roughly 14 m2 at 50mm deep, or about 9 m2 at 75mm. So a border of around 12 m2 at 75mm needs about one and a third bulk bags, so order two and keep the spare for topping up next year.

Delivery from our Leigh base is from £20, priced on your postcode and the size of the order.

For a mixed, planted border the honest answer is usually no. Weed membrane is worth it under gravel or in low-planting, low-maintenance schemes. In a border full of perennials and shrubs it gets in the way of planting, self-seeders root into the bark on top of it anyway, and it looks poor once it works its way to the surface.

A thick enough bark layer, 75mm, does the weed-suppression job on its own. Save the membrane for gravel areas and paths.

Lay it 50 to 75mm deep. Thinner than 50mm and light gets through, so weeds come up. Much thicker than 75mm wastes bark and can hold too much damp around shallow-rooted plants. For a fresh border where weed control matters, go for the full 75mm.

Spring, around March to April, or autumn, on soil that is already moist. Avoid frozen, waterlogged or bone-dry ground. A damp, mild day after rain is best, as the mulch then locks that moisture into the soil for the season ahead.

Measure the area in square metres and pick a depth. A bulk bag is about 0.7 cubic metres and covers roughly 14 m2 at 50mm or 9 m2 at 75mm. So a 12 m2 border at 75mm needs about one and a third bulk bags. TopTurf landscaping bark is £87 a bulk bag.

Generally no. Membrane suits gravel and low-maintenance areas, but in a mixed planted border it gets in the way, self-seeders root into the bark on top of it, and it looks bad once exposed. A solid 75mm bark layer does the job on its own.

As a surface mulch, barely at all. Nitrogen lock-up only becomes an issue if you dig fresh woodchip into the soil. Kept on top, bark has little effect, and any minor drawdown is limited to the very surface where few roots sit.