What Are Grasses?

True grasses are plants in the family Poaceae, a series of one-leaved (monocot) flowering plants including cereal grasses such as wheat, maize, barley etc., bamboos, and the grasses of grassland, pastures and lawns.

However, in a horticultural context, when we talk about grasses we are also talking about pseudo-grasses such as sedges and rushes, which are commonly also grown for utility or ornamental purposes in a garden. Though rushes and sedges are not true grasses, these members of the Poales order are still often spoken about as grasses – particularly in the context of ornamental grasses for a garden.

True grasses and grass-like sedges and rushes can all make excellent garden plants. Of course, it is common to use certain grasses to create a grass lawn. But ornamental grasses are also popular additions to beds and borders.

Popular Grasses Grown In The UK

Here are some of the grasses grown frequently in the UK:

When And How To Plant Grass Seed

Grass seed should typically be sown during the shoulder seasons, when the temperatures are neither too hot nor too cold for effective germination to take place. Avoid sowing the grass seed for a new lawn in winter, when cold air and chilly soil temperatures impede germination. And avoid midsummer, when the heat and dry conditions can reduce germination rates.

The soil should be at least 8 degrees C for grass seed to germinate successfully. In this UK, this usually means sowing from mid to late spring, or in early autumn before chillier weather arrives. In order to establish a new lawn or area of grass, sowing during both of these periods is usually recommended to fill in the sward.

Choosing your grass seed is, of course, the first step. Make sure that you choose an option or options that are right for your situation and needs. Once you have decided which grass to grow, make sure you consult the packet to find out how densely to broadcast the seed.

Remember, biodiversity is crucial for organic gardens. Consider choosing a seed mix that incorporates wildflowers and other plants in addition to grass for a wildlife-friendly, ecologically sensitive garden.

Whichever seeds/ seed mixes you choose, try to sow on a calm day, so the grass seeds are not blown about. Prepare the area before sowing by raking the area and removing any unwanted weeds and debris. Ideally, tread on or roll over the area to ensure the seeds are in good contact with the soil.

To further increase the chances of good germination, it is important to think not only about temperatures but also about water. Grass seed will germinate most effectively when the soil is moist, but not too wet or too dry. Add water by misting finely with a spray or using a fine rose. Try to avoid creating puddles on the soil as this can cause issues with waterlogging and compaction, or wash grass seeds away. Make sure the soil remains moist until the grass is growing strongly.

What Conditions Do They Prefer?

Most true grasses, including ornamental grasses and bamboos, will typically prefer sunny and well-drained conditions. However, there are also grasses that can cope well with more moist and waterlogged conditions, or in shade. No matter what soil type and conditions you are contending with, it is likely that you will be able to find a grass to suit the situation. Of course, it is important to choose the right grasses for the right locations, and to match up the requirements of a particular plant to the conditions that you are able to provide.

ornamental grasses swaying in the wind

If you are looking for options for a shadier or damper site, then sedges and rushes rather than true grasses can often be better options.

When making sure you can provide grasses with the right conditions, it is also important to make sure that you consider the needs of other plants grown close by. Many grasses can spread quickly and some types can have a tendency to take over beds and borders. So vigour and speed of spread should also be considered when choosing which grasses to plant where.

What Conditions Should You Avoid?

Make sure that you avoid placing grasses that are too vigorous or prone to taking over in areas where they will overwhelm other plants in your garden. And make sure that you do not place a certain type of grass in an area where it will not thrive.

If you are looking at grasses for a lawn or pasture, it is important to choose varieties that are suited not only to the environment but also to your needs. For example, if you want a neat swathe but do not want to have to mow too often, choose slower-growing grasses. If you want kids or pets to be able to play freely, make sure you select hardy and tough species, that can cope with the traffic levels. If you want the grass for animal pasture/ forage or feed – make sure you choose a grass mix suited to the animals you wish to keep.

If choosing ornamental grasses, make sure that the options you choose are of the right size, form, appearance and growth habit for your scheme. Think holistically about your garden design and choose grasses that will grow happily alongside your other plant choices, and look harmonious when placed among them.

Frequently Asked Questions

How Long Does Grass Seed Take To Grow?

Germination rates can vary. Remember, grass seed will typically take longer to establish in colder, more northern parts of the UK, and will establish more quickly in the warmer south. But grass sown in mid-late spring or early autumn will usually begin to grow in a couple of weeks. It is common for a new lawn or grassy area to be greened over within 6-8 weeks. Though of course how long exactly it will take grass seed to grow will depend on which grass or grasses you have chosen.

If you are creating a new lawn, you can expect grass to have reached the height of 5-7cm, and to be ready for its first mowing, in around 6-8 weeks. However, it is worthwhile considering a more biodiverse planting scheme.

Rather than making a mono-crop lawn, consider creating a more biodiverse meadow, or un-mown area with other plant species mixed in. It can take longer for such biodiverse schemes to become fully established, but the balanced ecosystem will bring many more rewards over time.

When Do Grasses Stop Growing?

Grasses will typically stop growing or slow its growth considerably when the air and soil temperatures fall below 5 degrees C. Throughout much of the UK, this typically occurs at some point in autumn, usually around mid-November in many areas. Though of course there is a great difference between when you can expect these conditions in more northern areas, and when they are typically expected in the warmer south.

However, the type of grass will determine whether the grass stops growing altogether or merely slows in its growth over the winter months. Perennial grasses will typically become dormant over the winter, or slow down. While annual grasses such as annual ryegrass and meadow varieties will naturally die.

If you mow a lawn, you can typically stop mowing in the coldest months, (Between around November and early March) but even so, it is important to recognise that even when there is no top growth, root growth will likely still be taking place. Over the winter, grass will typically put its energy into its root system.

So in late autumn and winter, even after you are no longer mowing if you did so before, you should be thinking about making sure that the grass’ root systems have the nutrients they need.

When Is The Best Time Of Year To Cut Grass?

When it comes to maintaining a lawn, less is often more when it comes to mowing. In an organic, wildlife-friendly garden, you may choose to forgo mowing altogether and to take a more naturalistic approach.

If you do mow, you will tend to do so between around March and November. But try to leave the blades on your lawnmower higher, and mow less frequently to give wildlife a chance. Consider mowing only pathways through a grassy area, rather than keeping the whole lot short.

When it comes to ornamental grasses, it is important to understand what type of grasses you are looking at when cutting them back.

Deciduous ornamental grasses should typically be cut back hard in early to mid-spring (depending on variety). Some deciduous species are cut back to ground level before new growth appears, others require later cutting back as old stems protect the crown and new growth.

Evergreen grasses usually only require tidying up. Small evergreen grasses can be trimmed to remove brown tips and to cut back dead leaves. Typically, sedges are not cut back completely but just cleaned up a little. Larger species of evergreen ornamental grasses benefit from hard annual pruning however, also in spring. With some types, you may wish to cut back as far as possible without damaging new growth.

What Should You Do with Grass Cuttings?

There are plenty of ways to use grass cuttings in your garden. To avoid waste and return nutrients to your garden, you should find ways to use them in your space, rather than throwing them away. For example, you can:

  • Scatter grass cuttings back over the lawn area, so nutrients can be reabsorbed into the soil. Just avoid leaving large clumps in place.
  • Use the grass cuttings as a mulch around annual crops with high nitrogen needs (leafy crops like brassicas – members of the cabbage family – for example).
  • Add the grass clippings to a composting system. (Along with plenty of carbon-rich ‘brown’ material like dead leaves, straw, cardboard etc..)
  • Compost in place and use grass clippings as part of new garden growing areas. Making lasagna beds or hugelkultur mounds involves layering different types of organic material to break down in place and create fertile and productive garden beds.
  • Make a nitrogen-rich liquid plant feed by adding grass clippings, weeds and other green plant material to water. Wait for the material to decompose in the water and the liquid feed can be beneficial for giving a boost to leafy vegetables or other nitrogen-hungry plants.

How Do You Know What Type Of Grass You Have?

Determining what type of grass you have in your garden is not always easy, especially if the grass is in a well-mown lawn.

But here is a brief guide to identifying some common UK species of lawn grass:

Dwarf ryegrass – typical for lawns, purple or reddish colouration at the base.

Red Fescue – popular cool season grass, with deep green colour and very fine blades.

Bent grasses – many types of bent grass are common in garden lawns and in the wild around the UK. If you have a garden lawn like an upland pasture, this is likely to be the type of grass you’re looking at.

Meadow grass – Poa pratensis forms a hardwearing turf and is recognisable due to its dark green leaf, that is a bit broader than other types of grass.

Looking at the conditions (shade/ light/ moist/ dry), and properties of some common lawn grasses for the UK should help you narrow down the field and discover what type of grass you have in your garden.

How Many Different Types Of Grass Are There?

The true grass family, Poaceae, is the fifth largest plant family. There are around 12,000 different species within this family, and that is without even looking at the grass like rushes and sedges that are also often called grasses.

How Can You Stop Weeds Growing In Your Grass?

The question should not be how to stop weeds growing in your grass, but why you would want to. If you want to have a more eco-friendly and sustainable garden then your goal should not be to eradicate weeds, but rather to welcome them.

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