No! It’s not as simple as watching for forsythia blooms…
Many people use forsythia as an indicator for crabgrass treatments, but forsythia
flowering should be the sign that it’s time to START planning pre-emergent
crabgrass control applications. Generally crabgrass germination is not expected
until after Forsythia flowers have faded and fallen off. Even then there are
many variables such as air temperature, soil temperature, sun exposure and turf
density.
Research has shown that crabgrass germinates when average daily soil temperature reaches 57 to 64 degrees at 1 inch depth. Even then many crabgrass seeds will not germinate until the soil temperature is above 70 degrees. Turf density, mowing height and soil structure all affect soil temperature and therefore crabgrass germination.
We can also use Growing Degree Days (GDD) to predict
crabgrass germination. GDD is based on the measurement of air temperature above
a base temperature of 50 degrees Farenheit. Science tells us that crabgrass
will germinate at about 200 GDD. (It’s the end of March and we’re still below
90 GDD.) However all those variables about soil temp, density, etc. still come
into play affecting exactly when this pesky weed will sprout!
Normally the first place we find crabgrass sprouting early is in sunny, hot
dry areas like the south side of a building in lawn surrounded by pavement which contributes
to heating the soil. Crabgrass likely won't sprout until June in more protected areas.
The key to success with crabgrass control is to properly
maintain the lawn with good fertility to increase turf density. Mow high to
shade the soil. And apply pre-emergent control before crabgrass sprouts!
The good news is that Weed Man applies two full applications
of crabgrass control that work as a pre-emergent AND a post-emergent. What that
means is that we protect the lawn with a blanket to keep crabgrass from
establishing, but if there is “break-through” our 2nd application
will stop the crabgrass plants from gaining a foot hold.
So trust us to take care of crabgrass and we’ll trust you to
take care of proper mowing and watering. Be sure to check with us if you need
advice on proper care of your lawn.
Call us at 413-736-9333 or 860-903-1110!
