[ryeguy]

A few days ago I mixed up some spectracide to spot spray weeds in my front lawn, which is about 4k sqft. I estimated I'd use 2 gallons of water walking in a grid pattern with a fan tip nozzle, so that's how much water I used. I followed the mix rate of 1oz/gal. I was right - 2 gallons was perfect for spot spraying my yard. But I'm wondering if this was the right thing to do or if it was too light.

The mix directions say 1oz/gal/250 sqft, and it says that works for either broadcast spraying (which I'm not doing) or spot spraying. If I had followed that, I would have used 16oz of product and 16 gallons of water. But this is where I'm confused - how can a label give spot spray instructions based on square footage without knowing weed density? If I only have, say, 2 weeds per 250 sqft, I'm obviously not going to unload a gallon between the two of them.

Is this solved by sprayer calibration? In this case, would I ideally know how much my sprayer puts out per 250 sqft, and adjust the mix rate based on that? Or something else?

 

[jimmy]

Just go with the mix rate listed and ignore the square footage. If you bought it premixed it would be mixed at that mix rate and you'd just use it for spot spraying and not worry.

Regarding the square footage, they assuming blanket coverage for that. If you add up all the spots you sprayed, it should be pretty close to what's listed.

 

[ryeguy]

Just go with the mix rate listed and ignore the square footage. If you bought it premixed it would be mixed at that mix rate and you'd just use it for spot spraying and not worry.

That's a good idea for something to check. I looked at the refill directions and the rate is actually 10oz per gallon, which is 10x more than the rate per gallon for spot spraying with a pressure sprayer! I know pressure sprayers put out more product but is it really 10x more than a premix sprayer would?

 

[g-man]

I estimated I'd use 2 gallons of water walking in a grid pattern with a fan tip nozzle, so that's how much water I used.

The key to spraying anything is knowing how much liquid you use to spray 1k. There are so many factors (tank pressure, fan tip design, walk speed) that you can't estimate.

Here are the steps I use to know my coverage/calibration. Fill a tank with 1 gallon. Measure an area(250sqft, or 500sqft) of a dry driveway. Go to a corner and start spraying in a straight pattern. Try to maintain the same nozzle to ground distance(how wide the spray is). Avoid overlaps and also avoid gaps between the lines. Walk the area 2 or 4 times to get to 1000sqft feet. Did you ended up with water in the tank? Then you are walking too fast. Ran out too soon? Too slow walking or nozzle too low. Repeat until you get it right and repeat next week before applying anything. Practice will make this second nature.

You could also do this with dye on the lawn if you don't have a driveway or using shampoo, since it helps the soil.

Expect the neighbors to ask about what driveway sealant you are applying.