Time release fertilizer in containers

schill93 · August 23, 2015

I am speaking of planters that are top watered by the way. I know all you organic growers are against synthetic fertilizers, but for those of you who are using them and are growing tomatoes in containers, do any of you use a slow release type fertilizer like Osmokote or Dynamite? If so, do you mix it throughout the mix, put it near the planting hole, or in the top 4 or 5 inches of the container soil? I have read all three as recommendations.

I have read so many articles from agricultural centers on this advocating it, but stating that it is too slow a release for tomato plants, so it still must be supplemented with a soluble fertilizer as well.

I have also read where slow release fertilizers are very effected by the heat, and that areas where temperatures reach well above 95 degrees daily (106 here in Las Vegas) that they may release too much fertilizer due to the heat. I think I experienced that in a Geranium plant. I believe I put too much in and when the really hot weather arrived, it fried it up. Can't say for certain, but sure looked like it.

One poster on here was just using a regular top dressing of I believe it was 13-13-13 regular granules mixed with Mittleider micro nutrients and was adding I think but not positive, a tablespoon as a top dressing to each container weekly. I would have to go back and find their post.

Anyway, I was interested in anyone who used either type of granules and your experience. I am familiar with the Earthbox and Earthtainer regular granular applications. But I am at this time more interested in experience with top watering containers.

clkeiper · August 23, 2015

I use it when I am planting up large pots in the Spring and mix it in the botom half of the mix. I then fill the pot and plant the tomatoes. For all my flats I just throw "broadcast" all over the benches. I also have an injector to fertilize when I water and I usually am fertilizing not plain watering the plants. So I do both, but you just need to follow the amount per pot size when you are doing it. Yes, you can use too much and burn them and yes, when it is hotter it is released faster so it needs to be applied more frequently than every 3 months or what ever the time frame is for the product. When it is hotter I wouldn't suggest using water soluble fertilizer then just plain water (It doesn't get that hot here).
I use enough of it that I buy a 50# bag of it in the Spring.

luigiwu · August 23, 2015

I do subirrigated container garden (ala Larry Hall's rain gutter grow system) A lot of subirrigated container gardening share the same principles that make the earthbox so successful. I put 1 cup of 10-10-10 as a ring around each 5-gallon bucket at the beginning of each grow season (shallow trenched and covered)

schill93 · August 23, 2015

Quote:

Originally Posted by luigiwu

I do subirrigated container garden (ala Larry Hall's rain gutter grow system) A lot of subirrigated container gardening share the same principles that make the earthbox so successful. I put 1 cup of 10-10-10 as a ring around each 5-gallon bucket at the beginning of each grow season (shallow trenched and covered)

The subirrigated container (rain gutter) is the same principal as the Earthbox or earthtainer, as the water is wicked up. Earthbox instructions tell you to lay a stip as you are doing using regular granular fertilizer and not to use time release. I assumed that was because they took too long for thirsty tomato plants and certain other vegetables. But when you water from the top, you are generally washing away nutrients, unlike SIP containers where it is contained and used more effectively.

I just made note reading some articles online that they mentioned using a slow release fertilizer in containers. My thinking was that either the fertilizer would not get dispersed as rapidly with the time release, and the regular granules might disperse too much fertilizer from the more frequent watering needed with containers. I don't know the reasoning behind it, and that is why I ask the question.

In other words, I know the correct way using SIP containers, but short of using soluble fertilizer for top watering containers, I'd like to know about using granule fertilizer with pots.

luigiwu · August 23, 2015

Sorry, I guess I don't understand the difference between synthetic fertilizer (10-10-10 and the 13-13-13 that you mentioned) versus the time release one I guess you're asking about and since I know nothing about top watering containers, I'll shut up already.

schill93 · August 24, 2015

Quote:

Originally Posted by luigiwu

Sorry, I guess I don't understand the difference between synthetic fertilizer (10-10-10 and the 13-13-13 that you mentioned) versus the time release one I guess you're asking about and since I know nothing about top watering containers, I'll shut up already.

No, don't shut up. I'll explain, best I can anyway. There are what I refer to as "regular granular" fertilizers like 10-10-10 or 13-13-13 etc. that release the fertilizer faster and it is available to the plant sooner, and also is depleted sooner. This is the typical type of fertilizer granular.

Then there are specially engineered granules that have a coating around them that for lack of a better word slow down and "ration" the release of the fertilizer in smaller amounts over a longer period of time. Here are a couple of articles about them.

http://bonnieplants.com/library/a-ru...rms-and-types/

And more detailed: http://edis.ifas.ufl.edu/hs1255

As an example Olmocote (which is one I mentioned) is a timed released fertilizer. It is expensive as it last longer and is more expensive to produce.

http://www.amazon.com/Osmocote-14-14...ZZ0PXX6HNTQZ1D

As opposed to an all purpose fertilizer like this one, which is the type recommended for SIP type containers like you have. (You can also buy other brands in organic as well)
http://www.lowes.com/pd_423093-1321-100513194___

zipcode · August 24, 2015

I now people who use osmocote with great success for seedlings (time is not as much however).
I see there are osmocotes with micronutrients and everything, sounds pretty good.
I don't see why you should supplement with liquid fertilizer, just add more osmocote at first, than you'll have a constant stream of more nutrients.
It's worth a try for sure, in case at some point plants seem starved because it was too ilttle or it ran out too fast for some reason, you can always add some inorganic fertilizer in the water, they are fast absorbed.
I am using organic with top watering, definitely more tricky, you can't react fast, I still haven't found the perfect amount/timetable for taste but production is still pretty good (up to 10lb per 5 gallon).

Ed of Somis · August 24, 2015

I have learned to use both water soluble and time-released ferts to my advantage. I use the time-released at planting and early season. These ferts are encapsulated in polymer balls that "release" the contents over time. It is not an exact science. I like the water soluble (like MG) because I can get immediate results (almost immediate)...and I can address situations by "reading" my plants.

August 23, 2015	#1
schill93 Tomatovillian™ Join Date: May 2015 Location: Nevada Posts: 275	Time release fertilizer in containers I am speaking of planters that are top watered by the way. I know all you organic growers are against synthetic fertilizers, but for those of you who are using them and are growing tomatoes in containers, do any of you use a slow release type fertilizer like Osmokote or Dynamite? If so, do you mix it throughout the mix, put it near the planting hole, or in the top 4 or 5 inches of the container soil? I have read all three as recommendations. I have read so many articles from agricultural centers on this advocating it, but stating that it is too slow a release for tomato plants, so it still must be supplemented with a soluble fertilizer as well. I have also read where slow release fertilizers are very effected by the heat, and that areas where temperatures reach well above 95 degrees daily (106 here in Las Vegas) that they may release too much fertilizer due to the heat. I think I experienced that in a Geranium plant. I believe I put too much in and when the really hot weather arrived, it fried it up. Can't say for certain, but sure looked like it. One poster on here was just using a regular top dressing of I believe it was 13-13-13 regular granules mixed with Mittleider micro nutrients and was adding I think but not positive, a tablespoon as a top dressing to each container weekly. I would have to go back and find their post. Anyway, I was interested in anyone who used either type of granules and your experience. I am familiar with the Earthbox and Earthtainer regular granular applications. But I am at this time more interested in experience with top watering containers.

August 23, 2015	#2
clkeiper Tomatovillian™ Join Date: Nov 2011 Location: ohio Posts: 4,350	I use it when I am planting up large pots in the Spring and mix it in the botom half of the mix. I then fill the pot and plant the tomatoes. For all my flats I just throw "broadcast" all over the benches. I also have an injector to fertilize when I water and I usually am fertilizing not plain watering the plants. So I do both, but you just need to follow the amount per pot size when you are doing it. Yes, you can use too much and burn them and yes, when it is hotter it is released faster so it needs to be applied more frequently than every 3 months or what ever the time frame is for the product. When it is hotter I wouldn't suggest using water soluble fertilizer then just plain water (It doesn't get that hot here). I use enough of it that I buy a 50# bag of it in the Spring. __________________ carolyn k Last edited by clkeiper; August 24, 2015 at 07:07 AM.

August 23, 2015	#3
luigiwu Tomatovillian™ Join Date: Jun 2013 Location: ny Posts: 1,219	I do subirrigated container garden (ala Larry Hall's rain gutter grow system) A lot of subirrigated container gardening share the same principles that make the earthbox so successful. I put 1 cup of 10-10-10 as a ring around each 5-gallon bucket at the beginning of each grow season (shallow trenched and covered) __________________ Subirrigated Container gardening (RGGS) in NY, Zone 7!

August 23, 2015	#5
luigiwu Tomatovillian™ Join Date: Jun 2013 Location: ny Posts: 1,219	Sorry, I guess I don't understand the difference between synthetic fertilizer (10-10-10 and the 13-13-13 that you mentioned) versus the time release one I guess you're asking about and since I know nothing about top watering containers, I'll shut up already. __________________ Subirrigated Container gardening (RGGS) in NY, Zone 7!

August 24, 2015	#7
zipcode Tomatovillian™ Join Date: Jun 2010 Location: Romania/Germany , z 4-6 Posts: 1,582	I now people who use osmocote with great success for seedlings (time is not as much however). I see there are osmocotes with micronutrients and everything, sounds pretty good. I don't see why you should supplement with liquid fertilizer, just add more osmocote at first, than you'll have a constant stream of more nutrients. It's worth a try for sure, in case at some point plants seem starved because it was too ilttle or it ran out too fast for some reason, you can always add some inorganic fertilizer in the water, they are fast absorbed. I am using organic with top watering, definitely more tricky, you can't react fast, I still haven't found the perfect amount/timetable for taste but production is still pretty good (up to 10lb per 5 gallon).

August 24, 2015	#8
Ed of Somis Tomatovillian™ Join Date: Jun 2013 Location: Somis, Ca Posts: 649	I have learned to use both water soluble and time-released ferts to my advantage. I use the time-released at planting and early season. These ferts are encapsulated in polymer balls that "release" the contents over time. It is not an exact science. I like the water soluble (like MG) because I can get immediate results (almost immediate)...and I can address situations by "reading" my plants.