Starting tobacco plants in waterbeds offers several advantages over traditional seeding. Waterbed tobacco plants allow for a quicker, less-labor intensive transplant of tobacco seedlings into fields. Proper fertilization ensures you have healthy tobacco plants to transplant.
Apply fertilizer seven to 10 days after planting the tobacco. By waiting, you reduce algae growth on the trays and reduce the chances of salt damage to your waterbed tobacco plants. Select a fertilizer with a low phosphate content, such as a 20-10-20 mix. Try to find a mix containing nitrogen primarily from nitrates rather than urea, the University of Kentucky Cooperative Extension recommends.
Measure the salt concentration in your water source using a conductivity meter. Calculate how much water you have in your float bed by multiplying the number of trays the waterbed holds by the depth of water in inches. Then, multiply this product by 1.64, which tells you how many gallons of water are in the float bed.
Measure the amount of fertilizer needed to obtain 100 parts per million of nitrogen, which is equivalent to 4.2 pounds of granulated 20-10-20 fertilizer per 1,000 gallons of water. Place the fertilizer in a large bucket.
Mix the granulated fertilizer in warm water to dissolve it. Pour the solution into the waterbed in several locations, and mix thoroughly, so the fertilizer distributes evenly. Use a submersible pump to circulate water if you like.
Fertilize your waterbed tobacco plants again four weeks after the first application with an additional 100 parts per million of nitrogen fertilizer, based on total waterbed volume.