1. Leave it pretty much as is
2. Renovate it
3. Remove some lawn for vegetable or flower plantings
Leave the lawn as is
If you are mostly satisfied with your lawn, then you should take steps to help it be healthy and weed-free this summer. Now is a good time to apply a pre-emergent herbicide. Pre-emergent herbicides or "weed preventers" are often used to control annual lawn weeds such as crabgrass, foxtails, barnyardgrass, spurge, knotweed, purslane and others.
A pre-emergent herbicide does not prevent weed seed germination or kill the seed. Instead, the root system development of a young weed seedling is severely limited by the action of the pre-emergent herbicide, killing it before it "emerges." Pre-emergents will not control existing weeds, but will, if applied before germination, control seedlings of annual or perennial weeds. To be effective, the pre-emergent must be applied before the weed seed germinates, which is typically in April in Jefferson County. Take a look at CSU Extension’s Planttalk 2118: Pre-emergent herbicides, http://www.ext.colostate.edu/ptlk/2118.html.
Early spring is also a good time to do a core aeration to reduce soil compaction. After aerating, you can overseed the lawn to fill in bare spots as necessary.
Renovate the lawn
You may want to consider renovating a home lawn if:
• the lawn species or variety is frequently attacked by disease or insects and it has caused the lawn to thin out,
• the landscape has become increasingly shady over time and the original lawn is thin and unhealthy,
• the lawn was severely injured or totally killed by disease, insects, or drought, or if it was winterkilled,
• you want to completely convert from one turf species to another.
Complete lawn renovation involves killing existing turf and replacing it with new grass. Partial lawn renovation may consist of introducing a new or improved variety of the same turfgrass species into an existing lawn, or introducing a similar-looking species into an existing lawn. For detailed information on when and how to renovate a lawn, download CSU Extension Fact Sheet #7.241, Renovating the Home Lawn, http://www.ext.colostate.edu/pubs/garden/07241.html
Remove lawn for vegetable or flower plantings
It’s not unusual to see homeowners replacing turf with vegetable gardens and perennial plantings. Many of us are realizing that we really don't need all that lawn. You can remove turf by digging it up or by killing it – it may boil down to how much physical work you are willing to do. If you opt for killing the turf, use a non-selective herbicide. The most effective of these products contain glyphosate. Glyphosate is only effective on actively growing grass and weeds, so the area should be well-irrigated to encourage plant growth before applying the herbicide. Read the label carefully and follow instructions on how soon the area can be replanted.
You could also build raised beds in an area that currently contains turf. Raised beds are easier to keep free of encroaching grass than ground-level beds. The elevated soil warms earlier in spring and drains more quickly after a rain. It doesn’t become compacted because you aren’t walking on the growing area. Raised beds also offer easier access for planting, thinning, weeding, and harvest. Organic Gardening on-line has an interesting article on how to build five different types of raised beds: http://www.organicgardening.com/learn-and-grow/five-raised-beds?page=0,0
Go outside and look at your landscape from several viewpoints. Consider how much lawn you really need. Early spring is a great time to start making changes!