I couldn't repot them right away (I had to wait 1 week to repot the purple and 2 weeks to repot the white). They were both severely rootbound when I took them out of the original containers, though they both perked up in their new home. When I first repotted them I put 1/4 cup of Bradfield Organic's all-purpose natural plant food (which is a 5-5-5 mix) into the hole and mixed it into the soil - they have not been fertilized since. The soil I used is Fafard's brand, which was suggested by the greenhouse in town.

Also, I trimmed off a few branches before repotting and put most of the main stem below the soil so more roots could develop, following the instructions I got with the plants.

I water them after I put my hand down to the top of my wrist in the soil and it comes out mostly dry, which is usually between 2 and 4 times a week. When the temperature drops below 45 degrees F I take the plants into the garage to keep them safe from the wind, and when the temperatures drop below 40 degrees I take them into the house. They get on average anywhere from 5 to 7 hours of direct sunlight each day.

What's going on with my plants? And more importantly, is there anything I can do to make them look and grow a bit better (especially the white, which isn't visibly growing)?

What would be the best way to check for/treat a fungal infection? And what would be the least invasive way to enlarge the holes, since the only tool I have at my disposal is an ice pick?

Yep, looks like sunburn to me too.

How long has it been since you transplanted them into the containers?

When you do water, does it run freely out of the bottom of the container initially or does it seem more like it is "seeping"?

Betsy