Correct, there is no value in doing either application now (the grass is not in enough active growth right now, even if some roots are growing, to need the extra nutrients). The fertilizer application would also be illegal. The lawn care company may want to brush up on MDA regulations, because Maryland has a blackout period from mid-November until the beginning of March when no fertilizer can be applied. Although lawn care companies do have a minor exemption in that they are allowed to apply a reduced-dose nitrogen fertilization for about two weeks after that cutoff date in November, we are currently past that extended deadline.

Ideally, they should have applied at least one fertilizer dose at the time of seeding, or very soon thereafter, as those nutrients help to get the new grass established. If they already applied 1-2 fertilizer doses since seeding, then the lawn is set and no further applications would be needed until spring (if then). You can learn more about the law's restrictions and recommended fertilization schedule and dosages on the pages linked above. (If the page above is updated, which we are trying to do in the next several weeks (in addition to most of our lawn pages), the URL should automatically redirect to the new page version.)

With regards to the weed killer, what weeds are they trying to suppress? Without knowing that, it's hard to make recommendations, though this is generally not the time when herbicide is applied. (Either pre-emergent, which needs to be put down before weed seeds germinate, or post-emergent, which targets weeds already up and growing. Usually the latter must be in active growth for the chemical to be effective.)

There are different categories of weeds depending on their life cycle traits. Winter annuals germinate in fall, overwinter in a dormant state (or may grow intermittently during mild periods), and mature, flower, and go to seed in spring. They die soon after. Based on this life cycle, any pre-emergent herbicide used to discourage germination is applied in autumn.

Summer annual weeds germinate in spring, mature throughout summer, and flower/seed before they die in autumn or early winter. Crabgrass is a typical weed in this group.

Perennial weeds like dandelion and plantain live for several years, so once they are noticed, they can be spot-treated with a post-emergent herbicide as needed, though manual removal is ideal to reduce herbicide use.

Each herbicide formulation has its own directions for use, which are listed on the label along with what weeds it targets. Selecting a chemical depends on the time of year, lawn type (some grasses are more vulnerable to damage, even if temporary, from certain chemicals), and weed type. You can ask the company to identify which weeds are present and what their intended plan is for which herbicide they intend to use for each. Avoid having them use a "weed-and-feed" product in spring, which combines fertilizer and herbicide. There are several reasons to keep those applications separate, and they should also be basing any fertilization decisions on the results of a laboratory soil test (one three or fewer years old).

We profile several common lawn weeds in the linked page if you wanted to learn more about their life cycles and options for chemical control.

Miri

Thanks very much, Miri.   

You're welcome!