bare tank

tom, i have two ten gallon bare bottom tanks sitting side by side for quarentine purposes,four foot shop light above. i like to throw extra plants in them to keep for later planting.without gravel can i expect to keep these plants looking good?i dose with excell,but should i also be using kno3 and po4? and if so at what rate of dosage?our local fish stores could use some advice to keep their plants looking better.thank you,regards, cornhusker