Sure, start hardening them off in a porch. Most annual seedlings can be placed in direct sun right from germination, but you should avoid this if they are under plastic or in an enclosed space without ventilation. They will grow much better in the sun than not. Start off with just an hour or two of morning sun if they have been under lights, then increase it after a few days. A porch attached to the house should be fine at night. The trick is to change conditions slowly, allow the plants a few days to get used to each change. They are perfectly capable of living outside in the conditions you describe, they just need to get used to it. The idea of peat pots is that you just drop the whole pot in the ground and the roots grow straight through it. I've tried it and it didn't work, so I'd recommend removing the pot. Cosmos love a free root run through loose soil.

The seedlings are growing their 2nd sets of true leaves...but how long can they stay in the soilless mix? When they're young, they basically live off their seed leaves. However, if they're working on their second set of true leaves, they're going to need some nutrients soon. You can start them off with a mild fertilizer solution (preferable) or get them into a richer soil mix.. And how long do they have to stay under the lights? Until they're hardened off outside, of course ;) I'd avoid transplanting unless you either need to thin out your seedlings or unless they outgrow their pots. Transplanting is generally a shock to plants. Will the plants be strong or even survive if they stay in soil-less mix and under florescent lights that long? Plants don't need soil to thrive. That's what hydroponics is ;) The sun is better than pretty much any light setup you'll build, but most plants can survive just fine under fluorescent lights, provided you make sure there's sufficient light. When the seedlings are 3" or 4" can they be moved to sunny windows and I can keep using the lights for the youngest plants? It depends on how sunny your windows are. You could consider supplementing them with additional light in their new location, if possible, such as a clip-on spotlight fixture with a bright CFL.

You do have too many questions to address properly here, but basically you cannot break into low frequency watering all at once. If your soil cannot accept all the moisture at once, you must stop when it starts to run off. If you can come back to watering 30 minutes later; however, the soil will have soaked the water in, and become more receptive to more water. With all the questions you have I'm going to suggest something that I think will do your soil the most good. Get a black plastic soaker hose long enough to stretch the length or width of your yard at least twice. So if your lawn is 50 feet wide, get 100 feet or more of soaker hose. Attach that to another hose that connects to your faucet. Find the high side of your lawn and start there. Stretch the hose out along the high side back and forth so the hose is about 18 inches away from itself (does that make sense?). Turn the faucet on to a trickle - where the water stream just barely breaks into drops as it hits the ground. Connect the soaker hose and let it run continuously for a full week, day and night. At the end of the week, you should be able to seed a wet mark in the soil where the water seeped. Move the high side of the soaker to that wet mark and move the low side 18 inches away again. Let that run a week and move again. Continue moving it weekly. You will have to continue watering your lawn normally all this time. When you have moved the soaker to the bottom of the lawn and let it run a week, move the soaker back to the high side and start over. When you complete the cycle for the second time, repeat a third time. At the end of three cycles, your soil will be completely different. What this does is set up a near perfect moisture and temperature environment to dramatically increase the population of beneficial soil fungi. Once you have the beneficials working for you in large numbers, your soil should absorb as much moisture as you can throw at it. When wet your soil should feel like a wet sponge (soft); when dry your soil should feel like a dry sponge (hard); and when you water the water should soak right in like a sponge. After you have your soil softened, you can go to weekly watering.

The weed n feed combined products are difficult to use and the results are usually unsatisfactory. I think all the forums will tell you that if you need to fertilize, use a fertilizer. If you need to kill weeds, use a herbicide (spot spray with Weed b Gon of WBG Chickweed, Clover, and Oxalis Killer). It could be the plantain needs the WBG CCO. It's a different bottle of stuff. Read the bottle label to see if 3 weeks is enough time between spraying. You should not get into a ritual of spraying it every few weeks, though. That's asking for trouble. You seeded at a bad time of year. Why? Because now is the time crabgrass seed is germinating. Also because tender new grass shoots will not have sturdy enough roots to live through the summer heat. Fall is THE time to seed northern grasses. As to fertilizer, the grass needs nitrogen. Whether it needs phosphorous or potassium, you can't tell without a soil test (Logan Labs, $25 - best soil test in the country by far). Having said that, you can apply an organic fertilizer like soybean meal, corn meal, alfalfa pellets, Milorganite, or corn gluten meal at any time without fear. These materials feed the soil microbes which, after 3 weeks, will feed the plants. Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, sprinkler and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall. Mowing: Mulch mow at the mower's highest setting for all lawns except bermuda, centipede, and creeping bentgrass. Those should be mowed at the lowest setting. Fertilizer: As indicated above. Dates are Memorial Day, Labor Day, and about Thanksgiving. Note that these dates do NOT match the dates you will get from TV commercials, local radio stations, and newspaper and magazine articles. These dates are the historical dates used by professional grass farmers and ranchers and have been adopted by the lawn community gurus as being the most appropriate for chemical fertilization. If you use organic fertilizer, you can do that any day of the year, or every day of the year. You cannot go wrong with organics unless you bury the grass in it. Spray on fertilizer is good for a few days up to a week. Grass needs pounds of nitrogen to last from season to season. All you get with a spray is fractional diluted ounces of nitrogen.