I disagree with Ken on this one and most Extension services out there do as well. The amount of nutrients in compost and garden soil is trivial and certainly not enough to create unwanted prolific plant growth in fall. You can incorporate compost (or garden soil) into your beds at any time. Doing so in fall is actually ideal because it gives it time to improve the soil structure for next Spring's growth. The link below supports my opinion as do several others you can find online. The very small quantity of slow-release fertilizer in garden soils, which is again much less by volume (0.08-0.05-0.05) than the nutrient content of compost (typically 0.5-0.5-0.5). Even if you were to add a slow-release now, it would not cause rampant plant growth. If you think about it, nutrients are present in most soils all the time. If the mere presence of nutrients in the soil caused excessive plant growth at the wrong time, we would have plants putting on tons of new growth in fall even without new nutrients added. It is when you flood the plant with nutrients, specifically nitrogen in the form of urea (which often occurs with quick-release fertilizers) that you see the sudden onslaught of new growth in fall. I add a light amount of Hollytone (which the directions indicate) to my acid-loving evergreen shrubs in the fall because nutrients do not just produce new growth -- they (namely, phosphorus and potassium) also help the plant's roots prepare for winter, regulate plant cell water management, and improve the plant's ability to resist disease. Here is a link that might be useful: Compost Is Fine in Fall

I cut my phlox back to just a couple of inches above the base. Phlox foliage often gets a bit of powdery mildew late in the season so I want to get that out of the garden before winter. To collect phlox seed after the flowers fade they will form seeds. They are ripe when they are dark and I pluck them off as they ripen. Some put a nylon or small bag over the seed head to catch ripe seeds as the ripe pods open easily and seed falls to the ground. I no longer add winter mulch to my phlox as they are hardy and survive well without it. We've had a couple of nights in the twenties. The few clematis and mums that are blooming seem to be unaffected by the low temps. Same for several other blooming perennials. Think the temps need to be low for a longer period of time to end their bloom. In my zone pansies are more readily available and displayed in the spring. Some mornings they look terrible from being frozen but as they warm the foliage and blooms perk up and they are lovely again.

Thanks bostedo, I really appreciate the info and identification. I'll probably plant it tomorrow or Saturday since I have the compost with gypsum. I recently planted the mistflower I got last week and I'm making sure I keep the soil moist, and the phlox will be in the same flower bed so I'll keep them watered as well. We saw them at a nursery earlier in the week and I commented on how pretty they were so she went ahead and bought them. :-)

Well I have been wanting white, but I certainly did not expect to get one that way:) no one seems to grow perrenials in my neighborhood due to the deer and there's no phlox at all other then mine so I am very pleased to have it. glad I did not throw those bits away. ( i have deer sprinklers which is why i have plants and the neighbors don't)