Garden BlogLawnSafe and Sensible Weed Control

April 26, 2021

Safe and Sensible Weed Control

Most homeowners groan when confronted with the task of removing weeds from their lawns. Although applying herbicides is not difficult, the risks and precautions involved in mixing, using and storing chemicals, especially in yards where children and pets play, are unacceptable to many people. Poisonous chemical pesticides remain well after application, and can wash down streams, or seep into groundwater. On the other hand, the prospect of spending hours digging out weeds is not an attractive alternative. Turf management is the key to a healthy lawn.

1. Mow lawns to a height of 6-7 cm or about 2 1/2 inches. The greater leaf area of longer grass makes its roots grow stronger while shading fallen weed seeds & preventing them from germinating. Longer turf is also more resistant to fungal diseases and is more drought resistant because it has deeper roots.

2. Mow frequently with a sharp blade and leave the clippings on the lawn as fertilizer. Clip only 1/3 of grass blades at a time. Long clippings increase the chance of disease.

Fertility: Most lawn weeds like dandelions, English daisy, plantain and thistles indicate poor fertility, compacted soil, drought or waterlogged conditions. Correcting poor growing conditions reduces weeds and strengthens the grass. Use slow release fertilizers or top dress every year or two with well made, fine compost. Do not over fertilize with soluble nitrogen because this stimulates soft, lush growth, which is more susceptible to disease, contributes to the build up of thatch and makes more frequent mowing necessary. Fertilize with slow release nitrogen like Fabulawn, or granular organics which are always slow release.

3. Lime can be applied lightly every year or two, especially if grass clippings are removed. This is necessary to make soil nutrients available to plants. It is not necessary to lime if your PH is over. Lime will not kill moss. Creeping buttercup usually indicates acidic soil, so adding lime can help.

Watering: Water turf deeply, but not often. Soak to the root zone (about 6-8 cm deep) and don’t water again until the surface 2 cm has dried out. This promotes deep rooting, drought resistant turf Overwatering creates conditions which kill grass roots and leaves room for weeds to become established. Shallow frequent watering promotes weak root systems close to the soil surface. Water in the early morning to reduce chance of fungal disease, twice a week at the most, applying 3-5 cm or 1-2 inches of water. Allowing lawns to become dormant in summer is fine, they will re-grow. Dormant lawns also reduce the infestations of crane flies, as the eggs and larvae (leatherjackets) do not thrive in dry dormant lawns. If your lawn goes dormant due to lack of water, do not water again unless you know it will not dry out again, this causes significant stress on new growth

Aerating: In compacted or heavy clay soils, it may be necessary to aerate the soil mechanically every year or two. A lawn aerator can be rented for large areas. On small lawns, repeatedly spiking the soil at a slight angle with a garden fork will suffice. After aerating, top dress the turf with sized sand (.25 – 1 mm), peat and sand or fine sifted soil or compost or whatever you prefer. This is especially recommended for lawns subjected to heavy use to improve drainage and aeration.

Thatching: Thatch is the layer of under composed organic material that accumulates at the base of the grass plants. Some thatch is beneficial, shading roots and reducing water loss, remove it if the layer becomes more than a centimeter deep. Grass begins to root in thick thatch rather than the soil and becomes more susceptible to diseases, insect damage and drought stress. Thatch management is best left to earthworms but can be done mechanically with a heavy rake or thatching equipment. Chemical weed killers can kill worms, which are a healthy part of promoting good lawns. New environmentally friendly weed killers like Weed Be Gon, or Corn Gluten “Weed and Feed” which provides nitrogen as well as inhibits the development of roots on newly germinated weeds can be a help to reduce unmanageable amounts of weeds in the lawn. Synthetic weed killers containing glyphosate or 2 4D etc are restricted in Courtenay, Comox and Cumberland and no longer on the recommended list for use by the homeowner.

Seeding New Lawns:

Pick up a Lawn Installation fact sheet for recommendations on how to plant a new lawn in our area from our service desk.

1. Weed seeds can lie dormant for years until cultivation brings them to the surface, therefore stimulate as many weed seeds to germinate as possible before planting. Cultivate and water the soil, wait for 2 weeks to allow weeds to germinate, cultivate them out then repeat the process. Seed the lawn after the second cultivation, or better yet, after a third cycle of germination and cultivation.

2. Choose an appropriate seed mix for the conditions: soil type, shade or sun, heavy or light use, etc. You might wish to include a small proportion of white Dutch clover in the mix on poor or compacted soils. It is low growing, stays green, resists drought and works to increase the soil fertility and break up compaction. Under good management, the soil eventually becomes so favorable for grasses that they will smother the clover.

Manual Weeding: Well-established rosettes of dandelions, thistles and plantain lie low enough to be missed by the mower and must be removed. Longer mowing heights and an improved management program will help to prevent new ones from becoming established. Dig out the entire root using a sharp weeding tool, a process that is much easier in moist soil. If a large weed leaves a gap in the turf, level the disturbed soil and sprinkle grass seed into the bare spot so that the turf fills in before weeds can germinate.

Environmentally Friendly Weed Killers: Try Weed B Gon, made from Iron, or one of the vinegar based weed killers. You can also make your own – Fill up a 1 liter spray bottle with white vinegar, add 2 tbs salt & a squirt of dish detergent. Be aware that vinegar will kill grasses too. Weed B Gone kills broadleaf weeds only when used according to directions.

Changing Perceptions: Reduce the weeding problem by changing your idea of what is a weed. Many people like the look of English daisies or dandelions and these weeds do attract beneficial insects to the garden. (Ever make dandelion wine?) Weeds with deep roots break up compacted soil and bring nutrients to the surface. White Dutch clover, in particular, should not be considered a weed because it is of long-term benefit to turf.

Modifying the Site: Some areas are weedy because grass just can’t grow well there. Shady areas under large trees that absorb the available water and nutrients could be planted with shade-tolerant ground covers or covered with bark mulch, gravel, stones or pavers. Heavy traffic areas and “short-cut” paths across lawns are often unsightly. Change the traffic pattern by fencing, planting hedges or using other barriers or consider mulching or paving the pathways or laying turf blocks in the travelled areas. Turf blocks are hollow concrete pavers that allow grass to grow in the center, while the weight of traffic is supported on the concrete.

Weed Prevention: Reduce the number of weed seeds entering the yard. Watch for flowering weeds along road sides, driveways and fence lines or waste areas and make sure they are cut down before they go to seed. If there is a patch of noxious weeds going to seed in your neighborhood, the owner can be forced to remove the weeds under the Provincial Weed Control Act (contact local B.C. Ministry of Agriculture, Fisheries and Food staff) or under municipal bylaws. Although the list of noxious species varies between regions and municipalities, Canada thistle occurs on all lists. It must be cut down before the flowers start to bloom or the seed will continue to ripen in the cut heads and scatter on the wind.

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