Are slow release ferts in containers necessary-your opinion?

[Suze]

I know that a lot of folks like to add some osmocote or its generic equivalent to containers when planting. But what are your experiences when you don't add a slow release to start out with? And, what do you do in that situation -- do you just start out with fairly frequent, weak low N ferts from the get go (or after first set) or what? Anything else you like to add (this is an open question). 8)

I have an opinion (which I'll express later, but don't want to lead/bias the question right yet)

:wink:

[SelfSufficient1]

I was hoping someone smarter would answer but I guess I'll start. Once I knew nothing about fertilizers(and now still know little so that's not saying much) and didn't add them. Someone gave me some mg which I started using and of course everything grew better. I then found the slow release ones and started adding them to everything I planted and things did good with that too. This year after reading on here I am just going to add cow manure to my containers and see how that works.
Ok, hopefully someone who really knows what they are doing will answer, lol.

[mdvpc]

Are they necessary? Depends on what you mean. I used to grow lots of tomatoes in containers using only foliar mg, but that was a long time ago. Now I believe that you need some slow release in to make sure your level of fertilization is steady and available for the plants when they want it. You can use osmocoate or tomato tone etc. I use a litle osmocoate because it breaks down slowly and a fair amount of tomato tone.

[jdwhitaker]

Are they absolutely necessary--no, but they are the best way to fertilize container tomatoes--or just about any container plant. Water soluble fertilizers (MG, 20-20-20, fish&seaweed) will work too, but can lead to a roller coaster effect of excess nutrients followed by a deficiency if relied on as the sole source of nutrients. My general rule is to use the slow release fertilizer as the foundation of plant nutrients in the container, then add a soluble fertilizer as needed during peak growth periods. Soluble fertilizer will especially help to add micronutrients, since most of the slow release pellets don't contain micros.

Whatever you do, don't count on the container soil itself for much in the way of plant nutrition. I don't use any manure or compost in the container soil I mix myself due to the fact they can impede drainage and aeration.

[honu]

jd, good point about roller coaster effect of non-slow release. However, I learned in my climate, even osmocote can burn plants since it is moisture and temperature activated, and our temperatures are often high enough to make it release too quickly.

Suze, for established plants that didn't get any slow release initially, I carefully poked some holes to work in fert around the plant, and it seemed to work ok. Might have cut a few roots in the process, but didn't notice any harm. Also sidedressed w/ some compost. My plants seemed to like it.

[MsCowpea]

honu--what you describe with Osmocote is a very common complaint in the nursery industry. I heard more than one orchid lecturor mention the weather-related 'release' of fertilizer with Osmocote.

They usually then recommend nutri-cote which is sold as Dynamite for the homeowner at places like Home Depot. It is more expensive but lasts longer.

http://www.arystalifescience.com/def...?V_DOC_ID=1601

Suze, I don't use time-release fert. at all in containers though I know it works well for many people (combined with other fert.) and is probably the easiest to use for beginners.

[Rena]

I have used slow release fert and also organic. At this point in my life (children) and the amount of watering my containers take I use the slow release. In my regular beds it is strictly organic. My soil needs all the improvement (coffee grounds organic matter) I can give it. If they could come up with a slow release organic fert that would be wonderful.-Rena

[honu]

MsCowpea, thanks for the link on nutricote.
This is the slow release organic fert that works well for my container plants:
http://www.organic-gro.com/1h-464.shtml

[jdwhitaker]

Good points about the slow release fertilizers releasing quickly in hot weather. They work well when weather is cool or just warm--but can release too quickly when temperatures are above 95. Plants don't need excessive fertilizer when they are struggling with the heat. That's why I don't depend on the slow release stuff for the total fertilizer needs of the plant, but apply them at a conservative rate and add soluble fertilizer as needed.

I saw the dynamite brand recently and it appeared to be good stuff--it had added micronutrients, which is rare for a slow release fertilizer. Micronutrients are often lacking in container growing.