You can sow seeds in as little as a week or even sooner after spraying glyphosate, a systemic, nonselective weed killer. Glyphosate moves from the leaves to the roots of plants, destroying the entire plant, but leaving no residue in the soil. The chemical affects many types of plants, including weeds, grasses and desirable plants, but after the liquid is absorbed into the plant, it doesn’t pose any further threat. You can safely sow ornamental flower seeds a day after spraying with glyphosate and grass and vegetable seeds, three days after, even though the herbicide takes up to seven days to destroy weeds. If you remove the dying weeds too soon, live roots could remain in the soil, ready to regrow. Another systemic weed killer that doesn’t affect seeds is pelargonic acid.
Pre-emergence weed killers prevent seeds from sprouting. They create a chemical barrier on the soil surface that suppresses seed development. What this means is, if you sow your own seed after applying a pre-emergence weed killer, the seed isn’t likely to grow. However, some pre-emergence products only affect grassy weeds, so you can safely sow most vegetable and flower seeds after applying these herbicides. The same doesn’t apply to reseeding or overseeding your lawn. Grass seed won’t sprout until a pre-emergence weed killer has decayed and become ineffective. For example, it isn’t safe to sow lawn seed until four months after applying a crabgrass preventer.
Sowing Seed After Applying Glyphosate
Sowing seed after applying a pre-emergence weed killer disturbs the chemical barrier on the soil surface, which means that weed seeds may germinate too.
It makes sense to be cautious about sowing seed after using weed killer. Certain herbicides can harm sprouting seeds and young plants. However, while you must wait several months to sow seed after applying some weed killers, you only need to wait a few days after applying others. The reason for this difference lies in the effect of the active chemicals in the individual products. Read the label carefully and follow all the directions when applying a weed killer.
Many selective weed killers leave little or no trace in the soil, and they target certain plants while leaving others unharmed. Generally, these types of herbicides destroy either grassy weeds or broadleaf weeds. You can safely sow most seeds in your vegetable or flower patch a day after applying selective herbicides, such as sethoxydim, clethodim and bentazon, for grassy weeds. These herbicides only affect your desired plants if the plants belong to the grass family. For lawns, herbicides that destroy broadleaf weeds are effective, but it isn’t safe to reseed until a month after applying these products, unless the label states differently.
Tools & materials you will need: Rotovator, Garden fork, garden spade, shovel, wheelbarrow, soil rake, pre-seed fertiliser, grass seed, weed killer, weed killer applicator, sprinkler, garden hose.
Step 5 – Sow Seed: There are various ways to sow lawn seed. The main thing is to ensure the seed is spread at the correct rate, usually 25-35gramms per square metre, evenly over the area and that the seed has good soil contact. If you do not have an applicator or seed sowing drill as used by professionals simply spread the seed by hand evenly over the area at 30-35 grams per square metre and lightly rake-in.
Step 8 – Aftercare
Step 3 – Raking: Rake the soil down to create a fine smooth tilth to remove stones and particles which are larger than 20mm in size. Firm in the soil by treading up and down the area in between passes with the rake. Scrape off high points and fill in low areas with a shovel. Carry out final tilth with a finer rake. Contractors may use powered rakes and other specialist machinery. Remove all arising’s such as stones and debris from site. Remember it is crucial to get the soil as smooth and even as you want the final lawn to be. Always bring soil right up to the same level as any adjoining paving or edgings.
Step 1 (to be done well in advance) – Kill Existing Vegetation: Kill off any vegetation such as weeds and grass with Glyphosate herbicide or similar systemic herbicide or thoroughly did out vegetation, or cover the area with a black plastic sheet several months prior. This will make life much easier for rotovating and will prevent unwanted weeds growing through the new turf.
Once you’ve trod the area start raking again to reduce bumps and fill depressions. If you’ve got the energy and inclination tread again in a different direction, rake to level and repeat one last time. Repeated treading will be required for an ornamental lawn as will the use of boards, levels and string to get a perfectly flat finish.
TREADING: Next comes the old fashioned art of ‘treading’ or ‘heeling’ the soil surface. It takes time but pays dividends in giving a flat firm finish. This is what true professionals will do as it is the only way to squeeze out air pockets and remove any likelihood of sinking later on. It’s the equivalent of kneading dough to make bread. With most of your weight on your heels just shuffle and tread up and down the area moving your feet about half a foot length each time. You need to tread every square inch of the prepared area so make sure you’ve got plenty of Radox because you’ll need a good soak afterwards!
The process of tilling the ground will have brought weed seeds to the surface which will germinate into your new lawn. You can do several things at this stage to reduce the impact:
At any stage during lawn preparation be prepared to pick up or rake out stones and debris such as roots. The quality of lawn you are constructing will determine how far you go with this process. And if perfection is your goal then consider bringing in double screened (1/4” sieved) sandy loam topsoil for the top few inches.
If you have had a soil test done now is the time to plan and order those amendments that you are going to make. These may include:
This final stage completes the preparation and readies the lawn area for sowing grass seed or laying turf.
For quantities that are less than this incorporate as follows: