Many of the plants we use as cool season annuals require a longer time to full plant development compared to summer annuals. A small difference in climate can make a lot of difference in what culture will work for these plants. I live in central Arkansas with a similar climate to that of donnabaskets. Because of our hot summers, many perennials such as delphiniums and poppies, along with the cool annuals, need to be planted in fall. But there are also those that will not survive our winter. Of the three plants asked about, I have no experience with lobelia, and only limited experience with nasturtiums and calendulas. Nasturtiums don't survive our winter. And for me an early spring planting has not worked well either. The summer heat seems to sap the plants before they can get well established. I tend to avoid them as difficult for my climate. That said, I have to remark that as a teen some forty years ago, there was a man down the street from me that had beautiful nasturtiums every year that lasted though the hot summer. I should have asked him the particulars to his method, but at the time mostly what I had on my mind was ... girls. Best I can remember the nasturtiums were in a spot that had very little direct sun exposure, but a lot of open sky indirect light. I seem to remember seeing partly decomposed horse manure being used and the pants were watered daily. Calendulas have a lot in common with nasturtiums; don't survive winter and take too long to develop before the heat of summer. But about 10 years ago I had a very strange thing happen with some fall seeded calendulas. They were started in flats in September and planted to beds in October. They grew lush and were bitten by the first frost, killed by the first hard freeze. But I had started more plants than I had used for the bed. These were left in the small cellpacks, the old kind that had 72 to the flat. Left outside, by late November they were completely root bound and stunted as small plants with no active growth. These cellpacks stayed out all winter and the soil in them froze solid numerous times. At the end of Feb. I chanced to notice that the plants were not dead. I was amazed. So I planted them in a bed. They took off like a rocket in March. I have as yet not tried to duplicate this method, so it may have been a fluke. But for that one year I had some great looking calendulas. Here is a photo of them inter-planted with pansy and ranuncula.

In Wyoming, zone 3, I would probably discourage using PR or TTTF if you have very cold winters. TTTF and PR can suffer cold kill in very low temps. Also if you have a lot of snow cover, then TTTF will probably have snow mold every year, which can also kill areas of turf. Fine fescues are very hardy once established, requiring little in the way of fertilizer or water but dormancy can be expected in hot, dry summers. If you go that route then I would probably use mostly creeping red fescue as it spreads, but be sure and get a named cultivar, not boreal which is actually common CRF. Kentucky bluegrass is also a good choice, but for your area you would need to choose a cultivar(s) that have very good spring green up and good cold tolerance. Many cultivars that do very well in lower latitudes will be dormant well into spring in your climate. -Can I mix a tall fescue mix with a fine fescue mix for more diversity or would this create all sorts of problems? You can mix most grasses, but you may not like how they look, and again, TF might have issues with cold kill/snow mold. -Will the KBG eventually out compete the Tall Fescues in the Defiance mix? No, but any areas of TF that die will probably fill in with KBG and or weeds, so over time you might have a predominantly KBG lawn. -Is it a problem or a benefit to have the perennial rye mixed in with the fine fescues? I have read perennial rye needs more water and fertilizer than fine fescues. Most seed mixes have some PR in them. The main reason is because it acts as a nurse grass, and makes consumers happy because they see germination in such short order. Unfortunately PR grows very fast when mature, and will not give you a consistent lawn. It does require more water and fertilzer than CRF too, as well as more frequent mowing.

"But what about after seeding? You have to administer starter fertilizer." You don't have to add starter at the time of seeding. Seeds will germinate all by themselves without starter. Actually it makes more sense to add it after the first mowing, when growth really starts to happen and it has long enough roots to actually use all those nutrients. I usually do a half app with the seeds, another half app after the second mowing. "I'm planning to seed in a week or two. But by the rule of thumb, won't the high concentration starter fertilizer compromise the existing grass if the temperatures are warm enough at the time it's applied?" If you are overseeding, it's probably better to wait till you mow for the first time. The starter will increase topgrowth and with all the watering you will be doing fungal disease will be an issue, and it will also crowd out the new grass to an extent. "I should add that my low concentration recovery feeding was just two weeks ago, during a cooler-than-normal span of a few days. " Doesn't matter, the fertilizer in summer forces topgrowth, which depletes nutrient stores, and increases the need for more water. For CT you want to shoot for around Labor Day, but that's just a way to remember it. When the weather turns dryer, and the nights cooler (low sixties, high fifties) is a good time for the first synthetic fall feeding.

The mycorrhizae enable the plant to more efficiently use what's available. It's like root extensions: the plant can get it from more places than just what happens to be right by the root. Sure. The question is, what is the real life effect of that? The plant lasts 10% longer? 20%? You get 5 days instead of 4? And what does that amount to? It needs to be quantified. You save 2-3 waterings across the span of the entire summer, maybe? It doesn't pass muster to me as far as cost (no fungicide, risk of turf loss) vs benefit (skipping a couple of waterings).