Although not the fastest method in the world for watering and feeding a seedling flat, bottom feeding(or watering) is quick and clean in areas for which space is tight and we want to keep clean.
Bottom feeding works fine for all of our plants, whether they be vegetable annuals like tomatoes and lettuce, or perennials like Columbine, Delphinium and Lupins.
For this procedure, all that is required is a seedling flat filled 2/3 full of liquid. A standard 1020 nursery flat is inserted into this and will saturate from the bottom up. In 10-15 minutes, we can remove the flat and place it into an empty flat to drain excess liquid for about 5-10 minutes.
Once plants cells are saturated and drained, they go back to their position under led grow lights.
If we do not have solid nursery flats and bottom feeding is not an option, we can water in a tight space with a pump and hand wand, pump sprayer, or watering can.
If we use a watering can, the medium in the cell tray should be a 1/4-inch or so lower than the cell walls so that water does not overflow while watering.
Once our plants are moved outdoors, we can use better watering techniques like a good pump and hand wand for feeding, and for more permanent plants, hydroponics and drippers.
We want to time our watering and feeding for maximum productivity while keeping our workload minimized. Thus, we want to ensure we use the proper watering system for our chosen environment whether that be a shelf of lights, greenhouse tables, flower garden or hydroponic system.