overfertilizing in containers, causes?

venturabananas · June 27, 2018

I've been growing tomatoes in containers for several years, generally 15-20 gallon pots. For the last two years, I've overfertilized, despite following the guidelines on the bag. The plants at the start of the season are growing downward curving leaves (sort of like a fern fiddlehead) and the flowers are dropping (in varieties I know should be setting, based on past experience with them). Last year, they grew out of it. This year, I'm too early in to say how things will change.

Last year I used Osmocote Plus, this year I'm using Tomato Tone. For both, based on the instructions on the bags, I added about 2.5 cups of either, per 20 gallon pot. That doesn't seem excessive to me, but the plants are acting like it is.

I'm wondering why this is happening.

I have a few of guesses:

1) I'm not mixing the fertilizer throughout all the potting mix in the containers. It's basically all in the top half. So the concentration is higher than recommended.

2) I usually reuse about 2/3rds of the mix from the previous year. Perhaps it still has pretty high nutrient concentrations. Though I wouldn't have thought so.

3) The potting mix I'm using (EB Stone Edna's Best) does have some organic ferts in it (e.g., bat guano). Maybe there's more of this in the mix than I suspected.

Anyone have any thoughts or similar experiences?

June 27, 2018	#1
venturabananas Tomatovillian™ Join Date: Feb 2012 Location: Ventura, CA Posts: 142	overfertilizing in containers, causes? I've been growing tomatoes in containers for several years, generally 15-20 gallon pots. For the last two years, I've overfertilized, despite following the guidelines on the bag. The plants at the start of the season are growing downward curving leaves (sort of like a fern fiddlehead) and the flowers are dropping (in varieties I know should be setting, based on past experience with them). Last year, they grew out of it. This year, I'm too early in to say how things will change. Last year I used Osmocote Plus, this year I'm using Tomato Tone. For both, based on the instructions on the bags, I added about 2.5 cups of either, per 20 gallon pot. That doesn't seem excessive to me, but the plants are acting like it is. I'm wondering why this is happening. I have a few of guesses: 1) I'm not mixing the fertilizer throughout all the potting mix in the containers. It's basically all in the top half. So the concentration is higher than recommended. 2) I usually reuse about 2/3rds of the mix from the previous year. Perhaps it still has pretty high nutrient concentrations. Though I wouldn't have thought so. 3) The potting mix I'm using (EB Stone Edna's Best) does have some organic ferts in it (e.g., bat guano). Maybe there's more of this in the mix than I suspected. Anyone have any thoughts or similar experiences?