Crocus care tips for May

Feel the benefit of a good mulch!

Mulching is one of the most important gardening tasks, whether you’re an old hand or a complete gardening novice. A mulch is simply a covering of material over the soil between plants that will reduce the need for watering and prevent weeds from gaining a foothold. There are basically two types: loose mulches which can be organic, such as bark chippings, or inorganic, such as gravel; and sheet mulches such as mulch matting, polythene or a piece of old carpet.

Why mulch?

Apart from looking good, an organic mulch offers six main benefits:

• it helps the soil retain moisture
• it insulates the soil keeping it warm in winter and cool in summer
• it suppresses weed growth
• it provides food for earthworms and other soil creatures
• it improves soil structure and water-holding capacity
• it adds nutrients to the soil as it is broken down.

Mulch is best applied now or the autumn when the soil is moist. If you apply mulch once the soil is dry in summer, it can actually stop any new moisture getting to the plants.

Beware:

depending on what kind of mulch you use, slugs and snails can make a home in it. If plants with mulch are attacked, scrape away the mulch immediately surrounding them.

Loose organic mulches

These help improve and feed the soil as well as providing a barrier to suppress weeds. It is best to apply a layer at least 7cm (3in) thick over the surface, taking care not to pile it up against stems. This will be thick enough to stop light reaching the soil surface and so prevent weed seeds germinating. There are many different materials to use, the best types are those that are long lasting with an open structure to let the rain in.

If aesthetic appeal is important to you, choose a decorative mulch such as bark chippings. These come in large chunks that don't blow around. Cocoa shells are easy to handle and bond together once laid; composted bark is more like compost in its consistency and so breaks down more quickly. In less prominent parts of the garden, well-rotted organic matter such as, leafmould, homemade compost or farmyard manure are good materials to use. They help condition the soil, improving its structure and water-holding capacity as well as adding some nutrients. However, be aware that some shop-bought manures may contain hormones, insecticides and herbicides. Stacking the manure mulch for a year will stop the majority of these returning to the soil. Sawdust can be also used as a mulch, but it should be at least two years old or it will use up valuable soil nitrogen as it decomposes.

Even dry grass clippings can make a suitable mulch around established plants such as trees and shrubs, particularly at the back of a border where the mulch is less obtrusive. Sprinkle a thin layer onto the soil where it will slowly rot down. The clippings also can be dug into the top few centimeters of soil, which will speed up its rotting process. Make sure there is no sprouting meadow grass among the sprinklings!

Sheet mulches

Inorganic sheet mulches are cheaper and much more effective at keeping out weeds than loose mulches and don't need topping up every year. However, they are less pleasing on the eye, can be awkward to lay and they don't add any nutrients to the soil. There are proprietary sheet mulches now available or you can use polythene, old carpet or even newspaper.

Plastic sheeting is a cheap and easy option. The plastic can be either laid between rows of plants or crops after planting or used to cover the whole bed and then planted through slits cut in the plastic. The sides and corners need to be dug into trenches to keep it flat and secure. As the plastic is unsightly it can be covered with gravel or soil to make it more attractive. Make sure that holes are punctured in the plastic so that water can drain through.

Old carpet is another popular weed-suppressing mulch used by organic gardeners. It is best used for providing a blanket cover if there is an area of ground that is being left fallow before being planted. It is very dense and thick so most weeds can't push through it, except well-established Japanese knotweed, which has been known to push through tarmac! Also, being heavy it doesn't need to be tethered. Brown paper or old newspapers can be used and can be dug into the soil after a year, again if appearance is important they can be disguised with a thin layer of soil or more ornamental mulches. Newspaper will set rock hard and take a long time to rot down, but if it is shredded it rots down much more easily.

Other jobs for the weekend

Plant up hanging baskets and patio containers with summer bedding
Propagate shrubs using softwood cuttings
Trim formal hedging such as box
Clear spring bedding and continue deadheading spring bulbs
Feed fish as they become active and feed pond plants with aquatic fertilizer
Propagate perennials from basal cuttings