10 tips for organic lawns
Carol Bucknell on how to get the best lawn on the block, without herbicides, pesticides and chemical fertilisers.
Get a great lawn without pesticides, herbicides and chemical fertilisers
get rid of the lawn. That’s the advice organic gardening pundits often like to dish out to would-be gardeners. Their mantra is that velvet green grass lawns are artificial constructs that do not deserve a place in the organic garden. It makes sense when you consider how much pesticides and artificial fertilisers the average lawn lover would use to maintain that lush green sward, not to mention the water requirements and the financial cost of all this.
But lawn lovers should not despair. You can grow very nice lawns without the use of chemicals and hundreds of litres of water.
These lawns may be a little more labour intensive to maintain and not quite so uniform in composition, but they’re much safer places for the kids, pets and wildlife to hang out. And of course there are no chemicals flowing into our streams and oceans because of them either.
1Work with nature
If you sow grass seed that suits the conditions of your area, your lawn is less likely to need pampering – constant watering, feeding, pesticides and so forth. For instance, if your area has very dry summers choose a drought-tolerant grass mix. This makes sowing grass seed a better organic option than laying turf as you can choose the seed mix that suits your specific requirements. An independent seed supplier such as Speciality Seeds (specseed.co.nz) can advise on cultivars that do well in a wide range of situations from shade, heat, cold, soils with low fertility to areas lashed by salt winds or subject to heavy use.
If you find sowing grass seed hard work, try using a lawn mat (like Woolgro). In this environmentally friendly product, grass seed is embedded in mats of unscoured sheep dag wool, recycled jute and paper fibres. These release nutrients in the soil and hold moisture, which improves seed germination and reduces the need for irrigation.
2View weeds differently
As the old saying goes, a weed is just a plant growing in the wrong place. Learn to live with a lawn that is a mix of turf grass and smaller weeds. Some, like clover, add nitrogen to the soil and provide nectar for bees.
Put your energy instead into the hand removal of large invasive weeds such as dock and dandelion (although many organic gardeners like dandelions as they attract beneficial insects to the garden). Some gardeners recommend simple, old-fashioned tools such as a screwdriver or Wonder Weeder for removing deep-rooted lawn weeds or you could go for one of nifty new tools on the market such as the four-prong weed puller from Fiskars (fiskars.co.nz).
Badly drained soils mean little air is penetrating into the soil, inhibiting grass growth and encouraging fungi and moss.
A simple solution is to aerate the ground with a garden fork, making a series of holes around 8-10cm deep in the surface of the lawn. For really heavy or hard soils, invest in or hire a hollow tine or core aerator machine and sweep sand into the cores you take out. Even for moderate soils this process will improve lawn health, especially if you add compost and top soil to the holes. For best results, do this after rain when ground is soft.
4Rake out moss & dead grass
Moss thrives in most lawns particularly during the wetter, cooler months. Resist the urge to spray it, just take to it with a rake. If you spray, you still need to rake to remove the dead moss anyway, so why not take the chemicals out of the equation?
Raking the lawn (also called scarifying) helps removes thatch, a buildup of grass rhizomes and stems that is so thick it doesn’t break down.
Thatch can quickly build up in between the soil and grass, preventing water and air from penetrating into the soil.
You can buy powered moss rakers (that also scarify) on the market if you’re physically not up to the job.
Moss prefers shady areas, so prune back trees where moss infestation is particularly bad. † TIP Thatching can be the culprit if your lawn is thick and spongy, or turns brown quickly in summer. Scarifying in spring and autumn will help. 5 Sweep out the fungi If you spot toadstools, mushrooms, puffballs and other fungi popping up in the lawn, don’t worry they won’t damage the grass. Their presence is an indication of decayed organic matter such as dead tree roots or a stump in the soil. Animal waste is another possibility. Sometimes fungi can appear if the lawn has been overwatered or is badly drained.
Reducing the frequency of watering can help as will removing thatch and improving aeration. Removing old tree stumps is another option although this can encourage the development of fairy rings, another type of fungi. Pruning or thinning surrounding trees to allow more sun onto the lawn will also reduce the shady, damp conditions fungi loves and encourage grass growth.
For an immediate fix to stop fungi from shedding spores, simply grab a stiff broom, sweep them off and suck up the debris with the lawn mower. While you’re at it, sweep up worm casts too. If they’re left on the grass, they can create muddy patches. Do this on a fine day and use a straw broom to spread the worm casts over the lawn as a top dressing. 6Thicken up your grass As we all know, a thin sparse lawn is a mecca for weeds. To compete with these invaders your lawn grass needs to be as thick as possible. Spring
or autumn are the best times to thicken up an existing lawn (or sow a new one) as the soil should be warm and moist for better seed germination.
Mow the lawn first. Then when the ground is damp, rake it well to remove thatch and break up the surface to around 1cm. This will help the seed make good contact with the soil. Add a layer of weed-free topsoil or lawn mix, then scatter the seed and water gently. Feed and water as for a new lawn.
Use the same method in autumn for worn or bare patches that may appear over summer.
Setting your mower high (7-10cm) gives your grass a head start in the neverending competition with weeds. Both want sun to thrive but tall dense grass can prevent light from reaching many weeds. Taller grass also has deeper roots that can choke weed growth and shade the soil more so the lawn will need less water.
Mowing a lawn higher doesn’t mean you have to mow it more frequently. Quite the opposite in fact. Mowing your lawn shorter reduces the number of grass blades to photosynthesise and feed the plant. For its own survival the grass must put on more growth as fast as possible after mowing. This accelerated growth uses up stored food and weakens the plant resulting in dead patches.
Longer grass grows more slowly and uses its stored sugars to produce more rhizomes, which means a thicker, healthier lawn. † TIP Regular mowing during the growing season helps reduce weeds and creates a finer sward. However, the golden rule is to never cut more than a third of the length of grass at a time.
8Leave clippings on the grass
There are different schools of thought on this subject, with some lawn experts extolling the virtues of leaving clippings on the lawn so they can add nutrients (mostly nitrogen, phosphorus and potassium) and organic matter to the soil, reducing the need for fertilisers. They also argue that the clippings act as a mulch protecting the soil from extremes of temperature and holding in moisture.
Others warn that leaving clumps of mown grass to pile up acts as a thatch and can kill off the lawn underneath. To avoid this, only leave clippings on the ground after mowing when the grass is less than 7cm high as they will decompose quickly. If the grass is any longer the clippings won’t break down easily and they’ll sit on top of the grass, effectively smothering it.
Mowing the lawn when it is damp can also make grass clippings form clumps. A mulching mower will help cut the clippings into shorter lengths.
Water only when your grass shows signs of drought stress and then water deeply. Even when it’s dry the lawn will quickly recover after rain or watering, and if it contains other plants besides grass it will have more drought resistance than a pure grass lawn.
Watering deeply forces grass roots to go deeper into the soil than most weed roots. Therefore when the top few centimetres of soil stays dry, weeds and weed seedlings die.
Shallow, frequent watering encourages thatching and if the grass roots are only in the top 2-5cm of soil they’ll quickly dry out on a hot day.
Watering also washes out soil nutrients so the less you do it, the more fertile your soil.
10Feed in the growing season The key to all healthy, pest-resistant plants is to keep them well fed. Feed lawns with an organic fertiliser in midsummer or autumn, then again in spring. Many experts recommend fertilisers that contain blood and bone such as Nitrosol or Yates Dynamic Lifter Organic Lawn Food.
Water in well if conditions are dry and make sure you spread the fertiliser evenly over the lawn.