Vegetables Gardening - Growing Organic Vegetables

Following is an exchange I had this morning with an alert Mittleider Gardener that everyone needs to read and be aware of:

"Please help me clarify fertilizer measurements in pots and grow boxes. There is an example in FAQ of 1.5 oz of PP per 0.5 cf. This is then used to figure volume for different sized pots. Then another response compares a 5 gallon bucket as 2/3 cf and states an 18" x 30' grow box would use 2# or 2 oz per cf. Wouldn't a grow box be 1.5x30x.66 for a cf amount which would be appx 30 cf. So 2# would be 32 oz which would only be about 1 oz per cf. I have several different size grow boxes and containers and am having trouble finding consistency in figuring out how much fertilizer to use. Thank you."

Growing seedlings is different than growing plants to maturity.  We recommend more WF & PP for seedling production because of:

1. Daily watering into flats & trays that have great drainage and thus lose much nutrition through leaching.  

2. The growth of plants is multiplied many times in only 2-4 weeks; 

3. Plants are grown very densely in flats or trays in the greenhouse.

Use the figure of 1 oz per CF for PP and 1/2 oz per CF for WF when growing plants to maturity in containers.

If you are producing seedlings from seed in flats or trays you should apply ONLY the PP to the soil before planting the seeds, and the amount is 3 oz per cf. which amounts to 1.5 oz (3 TS) in an 18" X 18" square flat and 1 oz (2 TS) in a 10" X 20" black plastic tray you purchase from a nursery.

For preparing the soil in flats or trays in which you transplant new seedlings you apply the same amount of PP PLUS 1.5 oz of WF per cf.  This amounts to .75 oz (1.5 TS) WF in an 18" X 18" square flat or .5 oz (1 TS) in a 10" X 20" black plastic tray.

Jim Kennard