GrownUps New Zealand

Gardening in October – Using mulches

October is the ‘calm before the storm’ for rose lovers before we head into November and December when the roses have their spring flush of bloom. But it is not a quiet time in the garden as there are still things to do including mulching. October is a great time to do this as the soil is still moist but is warming up with the increased temperatures and day length.

Mulching is the process whereby the soil surface is covered with a layer of organic or inorganic material for a variety of reasons. Two of the most obvious benefits of mulching are water conservation and suppressing weeds. By mulching your garden, water loss from the soil will be reduced and therefore you won’t have to water as often, therefore less pressure on water resources over the hot, dry summer months. Mulching also helps to prevent the soil from cracking and crusting during drier periods, therefore making it easier for water to penetrate the soil and reducing erosion through wind or water.

If you are anything like me, the last thing you want to spend your weekends doing is weeding so mulching is one way you can reduce the amount of weeds in your garden. There are tens of thousands of weed seeds just in a square metre of soil so even preventing a small percentage makes mulching worthwhile.

Mulching also protects the roots from temperature extremes. This is particularly good for roses as they like a cool root run during the hot summer months. In turn, roses that are mulched grow better and are less susceptible to diseases.

One of the great things about mulching is the wide range of materials that can be used in the garden, with the only limitations on what we use is the cost and our own preferences towards the various organic and inorganic types.

Organic mulches are those that break down over time and are usually plant material in one way or another. Examples of organic mulches include compost, bark nuggets, shredded bark, composted bark fines, lawn clippings, newspaper, pea straw, animal manure, sawdust, peat and fallen leaves.

We can also consider low growing plants or ground cover plants as a ‘living’ mulch and there is a wide choice of plants available. There is a wide range of plants that could be used so consult your gardening books, have a look around other gardens and ask other gardeners for their recommendations.

Perhaps the most important thing with such plants is to choose something that isn’t overly vigorous; otherwise, you will probably end up wishing you had never planted it as you spend every spare minute trying to get rid of it!

Inorganic materials are those that won’t break down and are either synthetic or natural materials; examples are weed matting, gravel or stones, scoria and old carpet. These are useful but unlike organic mulches, won’t add anything to your soil.

An article on mulching would not be complete without some handy hints to get the best out of mulching your garden. Like many things, preparation is one of the keys to successful mulching so give your garden a good weeding before you start, taking particular care to remove any perennial weeds such as docks, thistles or couch. They will regrow through organic type mulches because of the large amount of reserves that they hold in the roots.

There are a few things to be aware of when using organic type mulches in your garden. If you intend using them without laying newspaper or weed matting underneath, you will need to apply at least 5cm (2 inches) to prevent most weed seeds from germinating. If you are using newspaper or plastic, then you should be able to get away with less.

One of the problems with organic type mulches that are not well rotted (e.g sawdust, bark) is the fact they take nitrogen from the soil as they break down so add some extra fertiliser such as blood and bone when mulching.
If you are using sawdust as a mulch, make sure it is not treated otherwise you may run into some problems. Many of us also have access to lawn clippings to use as mulch, but it is important to apply it in a thin layer as they can generate quite a bit of heat. For this reason, it is best used along with something else rather than on its own.

Although you can mulch at any time of the year, it is best to mulch when the soil is warm and moist otherwise give your garden a very good soaking before mulching when it is dry. When applying, leave a gap between the mulch and the base of your plants as if it does, it may cause stem rot.

Happy Mulching!

In the rose garden for October:

 

By Hayden Foulds

Hayden also serves as Deputy Chairman of the World Federation of Rose Societies Rose Trials Committee amongst other rose endeavours. 

Read more from Hayden here.