I came home to my back deck's "garden," where I had baby perennials growing in plastic drinking cups (the disposable kind you see at parties), with one tiny nail-hole in the bottoms for drainage, stacked on shelves in open air (partly shaded). My plants looked quite happy and healthy without a greenhouse or twice-daily watering.

My question for professionals is this: what's the advantage of using pots with lots of big drainage holes? It seems to me that the water would run down the edges and right out the bottom without saturating the root ball. My plastic cups each have a single small nail-hole poked in the bottom, so they hold the water longer, long enough for the capillary action to reach all parts of the soil, then dribble the excess water slowly through the single drainage hole. So sometimes I don't even have to water every day! Why isn't this more commonly done? Does it actually promote fungus or disease, or does it compact the soil too much? I haven't had either problem yet, but I've only been doing this for a little while.

Also, what's the advantage of growing perennials in summertime under a greenhouse? My plants are growing up in the air temperatures and weather conditions that they will be living in once they're in the ground, instead of in a greenhouse.

Thanks all!
Regards,
Tara.

But, you have a very valid point......as much as possible we try to grow what we can in a natural environment. The plants seem healthier and more acclimated.

As for drainage hole size, most of us start our plants off very tiny. Tiny plants are succeptible to overwatering. I purposely choose media and pots to provide excellent drainage. I can always add water, but if they're too soggy, try taking it out. LOL.

Another thing they might be dealing with that you aren't is uniformity. They need all of one crop to be as identical as possible - it realy helps them market plants. Growing under controlled conditions like a greenhouse gives them that level of uniformity.