Impatiens being a shade plant will not flourish in high temperatures. Even if you got them to germinate it is unlikely they will do much outside in the heat. You have so many tropical plants that others can't grow pick one and grow that. I would dearly like to grow some plants that just won't tolerate my climate. That is the nature of plants and we gardeners have to adapt

Currently the basement is around 52-53 degrees. ... I am wondering if somehow enclosing the grow area of 4 4 foot lights and add a small heater would work? Do you mean 4 4 foot bulbs or 4 4 foot 2 bulb fixtures for a total of 8 40 watt bulbs? If your room or enclosure is sufficiently small, (I'm guessing less than 50 square feet), there is a very good chance that 320 watts of lights alone will raise the air temperature to at least 65o and the temperature of the leaf surfaces even more. It will take maybe a week for the air temperature of a room to reach equilibrium because it takes a long time for walls, ceiling and floor to warm up. Practically all of the electrical power going into lights ends up as heat. You can always burn a candle for a little extra heat and C02.

The greenhouse should be okay. Keep the humidity up. Alex is a rainforest plant so likes the humidity without extremes of temperature. If you get some of the savanna/woodland species, like a lot of the Livistonas, they'd really appreciate the 35's right through and not be worried by lower humidity.

Here's my never failed me yet over 30 years method. New 18 oz. cups with hole drilled or cut in bottom. Potting soil (I like Miracle Grow seed starting mix) 8 qt size, 2 bags. Mix that with 1 pound bag of Vermiculite. Fill cups and wet soil with HOT water until water drains from bottom. Make small circle in soil with my thumb and plant 3 seeds. (Allow soil to cool just a little so it doesn't cook the seeds). Cover seeds with a tiny amount of soil (1/8 inch). Place all the planted cups on a tray under the grow light. Cover cups with plastic wrap. Put lights down to about 1/2 to 1 inch away from tops of cups. Don't let light touch plastic wrap. Set timer to on 16 hours, off 8 hours. Walk away. I almost always have tomatoes up in 3-5 days. Take the plastic off AFTER the tomato has shed it's seed coat. If they don't all do it at once, cut the plastic wrap off of the ones that have without cutting the tomato. I cut the extra tomatoes off at the soil line before they get very big. I keep the light so close after this that the tomatoes grow up into the light, but not enough to damage them when removing the tomato growth from the lights. I fertilize when the tomatoes get pale in color. For your stage of no germination... I would make sure the soil is damp, cover with plastic wrap, put the lights close to the plants, and watch. I am assuming you have used sterile potting soil. If you have no results in a week, start the over. (Something I did before I started my method.) Whatever you do, keep trying and you'll get it down. It's really fun when you get the hang of it. Here's my hot peppers for this year. I use the same method. The peppers take a little longer to germinate. Rebecca