Annual core-aeration of a lawn is highly recommended, particularly if it receives moderate to heavy foot traffic (from people or pets using the lawn regularly). This reduces soil compaction, which improves root health for turfgrass, enabling it to better compete with weeds and stay healthier overall. Crabgrass germinates in spring, and in lieu of using a pre-emergent herbicide to prevent germination, the best approach for discouraging it in future years is to keep the lawn vigorous and dense, which includes annual overseeding in early autumn. (This can be done after core-aeration.) Buy recommended cultivars when you can find them among grass seed options, as this improves the lawn's resistance to disease and weather stress that helps it compete with weeds so they don't gain a foothold.

Crabgrass also tends to be worse in lawns that are mown too short, so make sure the mower you're using is set to have the blade height near the highest setting, around 3 inches, or even 4 inches (if you have tall fescue, the most common lawn type in MD). Under-fertilized lawns can also be more vulnerable to weed encroachment. Stay within Maryland legal limits for nitrogen applications (listed on the linked page), but focus on fall fertilization to boost lawn vigor, if you don't already. There should be organic lawn fertilizer options on the market; take note that, to comply with Maryland's lawn fertilizer law, any lawn fertilizer cannot contain phosphorus [P] if a laboratory soil test of the lawn's soil shows that it is not low on P. (If it is low, it can be used.) We can help to interpret test results if you wish.

Wiregrass (Bermudagrass) is a very tough weed to manage, especially organically (since organic options won't be systemic, where they are absorbed and moved into roots to kill them). Wiregrass also tends to thrive when lawns are mown too short, though they can still be a problem in properly-mown lawns. One option is to dig out patches/clumps of the weed, tedious though that may be because it will probably have to be repeated until you get it all. Another option is to try using an organic herbicide to weaken the plant, which would require repeated treatments (applications made to the weed only, not the whole lawn) since those products will only remove above-ground growth and will not affect roots. Eventually, if prevented from growing by constantly having its foliage "burnt" off by herbicide, it will weaken and die or be easier to dig up. Even so, that process might take well over a year to work.

We would suggest not core-aerating parts of the lawn with a bad Wiregrass infestation until that's under control, since the soil cores pulled-up by the machine could contain pieces of root/rhizome that may allow the Wiregrass to colonize new areas of lawn if it doesn't desiccate in the meantime. Since Crabgrass is an annual, though, any plants accidentally spread through core-aeration (less likely) will die during the next winter.

Miri