Tips for successful greenhouse experiments

Do not pack pots with dry media--sometimes pockets of dryness will remain (even after subsequent watering) that will damage developing seedlings or transplanted roots. Instead, pre-wet a large amount of media in one of the black mixing bins so that the media is somewhat moistened but not dripping wet.
If your experiment is going to be several months long, add a fixed amount of slow-release fertilizer to the media.
If your plants are susceptible to aphids, consider adding slow-release, system insecticides to the pots.
Small pots dry out in several hours during hot weather, so use a larger pot size if you want to ensure that your plants do not die on hot weekends.
Use clear-plastic saucers for pots that are drying out too quickly.
Do not use the "shower" nozzle setting when watering your plants. Although the shower setting can quickly wet the surface of large numbers of pots, invariably a good fraction of pots receive inadequate amounts. Because all the surfaces are wet, you won't know which pots need more. Surface-watering will result in poor root formation and, on hot days, will produce "crispy" plants in pots that didn't get the right amount. Instead, use the "drench" setting (at right) for each pot, and wait until the pot begins to drain from the bottom. Pot-by-pot watering takes about 10x as long, but is critical to prevent loss of plants.
Pots on different parts of the benches will dry out much faster than other locations, so usually "spot watering" is needed every several hours on hot days. Spot water with the "drench" setting, of course. Note that sunny days on cold days will sometimes result in greenhouse temperatures in 90s, so do not relax during the winter.
Do not water pots that are clearly fully wet already -- doing so will just cause root rot, fungus growth, and algal growth. Eventually, fungus gnat larvae will begin to develop, and will eat root tips.

Greenhouse | Bio. Dept. Facilities | Biology Department | Swarthmore College