Some that I have had very good results with here in east Central MS are: Zahara, Magellan, or Profusion zinnias, Angelonias (Serena and Serenita are easy to start from seeds), Cataranthus (Vincas) of all kinds and sizes, Gomphrena, especially Buddy, Victoria Salvia, lantana (sometimes perennial). I love Marigolds in the fall. I start them in pots from seed the first or second week of July. They go into beds to replace things that are pooped (usually because of not getting a mid summer cut back) in late August or early September. They bloom non stop until frost in November. I have never had problems with spider mites on them at that time of the year. And yes, they do need deadheading, so I don't overdo the number of plants I put out. Their colors just work so well for fall, so I am willing to pay the price. You probably know, but just in case you don't, use a good organic mulch on your beds to minimize the amount of watering the plants need. Keeps down weeds too.

I'm just south of you in Zone 5 Chicago and this is a big problem for me. I'm trying to perennialize most of my container garden to make it easier to maintain and get going each Spring. I haven't found too many perennials that survive our winters in containers (even though many survive fine in ground). The main plants that survive for me so far are various mints (ginger, chocolate, pineapple), chives, and certain oreganos and that's it. I'm only now experimenting with bulbs but none of the tulips I planted years ago survived past their first growing. Other bulbed plants like potato vines won't survive outside but if you bring the bulb inside and store them in a dry space they will grow back the next year when planted again. Another thing I tried successfully is planting wildflowers seeds in the fall and they will sprout and grow the next Spring without having to do anything. Unfortunately a lot of seed mixes have perennials that require a second year to become established and they just won't make it to their second year outside in the sub zero temps.

Some Random Thoughts 1. I am no expert, but as I understand design, a symetrically balanced formal garden is among the most difficult to pull off. Upkeep and maintenance become more critical because flaws are excentuated by the effort to achieve a pattern. Here's a quote from a very brief on-line article that points out some potential problems  "A view demonstrates balance if the objects in it are sited so that their visual weight is evenly distributed. Formal designs often display symmetrical balance, with the left and right sides of the view being quite identical  "The Courts is one of Wiltshire's best-kept garden secrets, known to visitors for its water features with surrounding topiary and its imaginative use of color and texture. The formal water garden is a favorite area of The Courts  Symmetrical balance dominates this view: the water garden shape is rectangular, the Siberian irises on either side anchor the view, and the pair of simple containers on formal stone pedestals in the foreground complete the symmetry. The less-formal tree borders beyond the topiary and the less-formal arrangement of water lilies keep this garden from feeling stiff. The formal water garden actually helps the viewer make sense of the space, lending a feeling of calm and serenity. "There is one word of caution if you plan to use symmetrical balance to draw attention to part of a landscape. Maintenance is critical. A formally clipped hedge, for example, can become an eyesore if a section of it dies." 2. Some comments in your original post have me wondering about this issue of maintenance. You say, "We have had a lot of disappointments in the garden"  "so that even when the rest of the property is covered in weeds and is a mess"  3. I just did a search at this forum for "formal". That may bring up further clues and suggestions that will help achieve your goal. I hope that these early morning musings prove useful in somehow stirring your creative juices. Not sure they'll be of any help at all, but thanks for getting me thinking, too. Wellspring

Karen, I'm glad to hear that you also have the inclination that adding mineral soil is the right answer. When creating the beds, I wanted to add good soil with lots of organic matter, and I also wanted to avoid spending a fortune on it. The topsoil/peat/manure mix was good for that, and it's been an absolutely fabulous growing medium with excellent water-holding capacity but also excellent drainage, but overall was probably too high in the organic matter for long-term stability. It's also possible that the heavy rains earlier this year contributed to the higher rates of decomposition and therefore more shrinkage. I will say that I'm not looking forward to digging up and replanting all of those plants, plus all of the additions to the bed, yet again. The herbs are even bigger, being a year older, and even last year they had larger root systems than I ever would have imagined. Some are due for dividing, which is fine, but leaving the others exactly where they are would have suited me. Maybe I can get by another year with the current levels, and only moderate topping-up.