Tips for Beginners: The Advantage of Watering Seeds and Plants from Below
Dr. Mark Konrad
Proper watering is a vital part of good plant culture. This becomes even more important when using containers because of the difficulty in getting an even distribution of moisture through-out the medium. To eliminate some of this inconsistency I have found that watering from below can be a helpful, supplementary aid to watering from above (see Figure 1.)
Figure 1. Watering seedlings from below.
Photo by Mark Konrad
My current technique with seedling culture is to use 5-inch azalea pots (20 seedlings to each) with a plastic sheeting cover. Sometimes excessive moisture accentuates the problem of leaf tip burning which occurs with some seedlings when watering from above. I have been encouraged by the improved seedling appearance when watering from below. Several other options for getting a more even distribution of moisture in the containers include the use of wetting agents as well as the use of super absorbents (see reference). Other advantages when watering from below include 1) the potential for back flushing an excessive fertilizer concentration or 2) at the other extreme, the ability to add a dilute liquid fertilizer if added nutrition is indicated. When applying a surface application of fertilizer, then watering from above is, of course, necessary.
The major benefit has been the more even and sustained moisture content with decreased need for frequent watering.
A brief review of some potential causes for leaf tip burning would include:
1. Over fertilization, especially with nitrogen.
2. pH either too high or too low.
3. Excessive moisture (causing oxygen deprivation).
4. Plant sensitivity to fertilizer. The species R. griersonianum and its hybrids might fall in this category.
5. Excessive heat, humidity or both.
6. Genetic incompatibility.
7. Excessive light.
8. Plant disease or pathology related to poor culture.
9. Juvenile sensitivity to fertilizer in any amount (a case might be made that fertilizer should be withheld the first 6 months or possibly even longer).
10. Or any combination of the above.
Ellis, Barbara W. 1983. Super absorbents save time and money. JARS 37: 2: 76-77.
Dr. Konrad is president of the Great Lakes Chapter.