I see no limitations as to what you can do on your property. The only drawback to widening the bed is if you have a grass like bermuda that puts out runners. It will be difficult to dig out and keep out, and edging is required. If your grass is bluegrass, etc., it will not come back, except from seed. Fall and Spring are good times to dig: it is cooler weather for the plants and you.

As you dig grass out, you will find that you have plenty of room to add and mix compost into the soil. Decide what you want to keep that has spread from the neighbors' yard into your bed, and disturb those plants the least when you dig. You can even transplant things to more suitable or aesthetic locations as you dig. Liberal watering will help save those plants that you disturb.

In my zone, Autumn and Spring are optimum times to plant some perennials, especially trees. It is also a good time to start plants from cuttings. You might check the FAQs on the GardenWeb if you need info on how to take cuttings.

Best wishes

The first matters to be decided are:

what do you want to plant; and what will you do to keep the garden and the lawn from mingling again? Or are you happy about trimming the edges each time you cut the grass?

How much sun does this area get? Are there any areas overhung by trees or harbouring tree roots from next door or your place?

You could be seeing early bulbs putting their snoots above the soil. They would probably have been underground at the time you moved in. Jonquils are the most likely. Daffodils tend to arrive a bit later. Lily of the valley probably won't show until well into spring.

Autumn is an excellent time for preparing beds for the next growing season.

If you mark out the size of garden you want and decide whether you want a long straight bed, one with a waney edge, or one with coves and headlands, and how you'll keep the lawn out of the plantings. (Concrete mowing strips, bricks, treated timber or rot-resistant timber, metal edging - whatever.)

You can either weed it 'properly' or just start by sprinkling a good all-purpose garden fertiliser over the old bed and the weeds. Next, cover it with material that will have mostly rotted away by the end of winter, despite the cold. Bushels of autumn leaves, grass clippings, seaweed if you're by the sea (oops, Indiana. Pond weed could be an option, though.) Finely shredded bark. Half-rotted compost that won't attract vermin. Shredded paper covered with something green such as soft weeds and grass clippings.

Put it around the bulbs, spiderwort, and phlox but don't cover the plants or they might rot away. The fertiliser will help them, too.

On the awful clay part, if it's suitably sited (rarely!), you might want to put in something like a seat and arbour, garden statuary or a bird bath/bird feeder, raised planter. Or really drench it with piles of compost forming material and keep doing so until it's deep enough to plant into.

If you can recognise the worst of the weeds - the persistant perennials such as buttercup - dig them out now and put them to rot elsewhere.

When spring comes they'll all come up through the mulch-turned-compost and you can take them out as soon as you can work the soil without ending up with half the garden clinging to your spade or fork.

If you make it a habit to put your grass clippings on this new bed for all of next summer, then add the fertiliser and leaves again you'll be on the way to building up a good workable soil.

If it were my plot I wouldn't put in any perennials next year. Just annuals, while I work up the soil. If I did weaken and buy Great Bargains then I'd also buy in bagged compost and plant any perennial or shrub for this area with plenty of good stuff mixed with the native soil. That way I'd know I'd get a better response from my new plants.

Any time, except when the ground is too hard to dig because of the cold, is a good time to start or improve a garden!

Fall is a great time to plant trees, shrubs and perennials because they want to sink their roots in first before doing anything else. Through the fall and winter is a perfect time for them to do this. When the new growing season starts your plants will do well.

I have just moved into a new home myself which had one miserable shrub that I removed because it was busy dying.
I have a bad back and so I do lasagna gardening. This past week I made all the new beds - some I have planted and some are going to break down over winter to rich soft soil beds. Do try it. It's not back breaking work at all and the results from all the nutrients in the layers is fantastic. This is also a solution to your clay soil problem.

Potawatami,

The short answer to your questions are it is never too soon to start improving soil and the single best way to do it is adding compost or material that will turn into compost.

Lasagna was mentioned and it is a terrific thing to do, but that method does 2 things. First it smothers anything currently growing (which makes it well suited to starting a garden on top of weeds or a lawn) and then it decomposes into compost. If smothering the existing vegetation isn't something you want to do then just skip to the chase and add an inch of compost dug into the first few inches of soil (a couple inches in the really rock hard clay where nothing grows and then top it off with an inch of compost on the top. All done. Each year, once or twice add more compost as it breaks down (compost will not permanently raise soil level as it breaks down to next to no volume).

my thoughts, improve the soil this fall, replant whatever you can and plan over the winter. this fall-just remove the soil where nothing will grow to two shovel fulls deep, since it is only 8" wide, it will probably take up only one wheelbarrow or two-dump this soil in an area of the yard you can easily get to so you can improve it later. Now refill that area with better soil from somewhere else in the yard or better yet, buy compost (by the bag or garbage pail-see if your community offers it for free) and mix some of the original soil with it. compost alone is not the best medium for growing plants-they wants some of the minerals that soil offers too. We don't know where this bed is, just between 2 houses, seldom seen and shade--plant hosta. between the concrete driveways in full sun and visible to everyone--plant low growing things--lemon thyme smells great when stepped on while getting out of your car. I like the idea of a bench and arbor ($$?) but buy a sturdy arbor, as my cheap arch was destroyed last winter by snow on my vine and stong winds, I rebuild it with salvaged swing set legs. see if a local garden club has a plants sale, or a plant exchange. pick all your plants to grow with the same conditions--same sun requirements, same water conditions. another problem to consider is the water issue-you might want to put a soaker hose under your mulch when you finish the bed next spring. have fun-and remember seldon do gardeners leave their beds the same year to year-decorators move funriture and we move plants.