Best Fertilizer for Containers?

yumtomatoes(10a/FLA)February 20, 2011

This year, I germinated my seeds in Miracle Gro Moisture Control soil which has some (relatively) high in nitrogen slow release fertilizer in it. I am growing in containers so I am sure the fertilizer gets washed out before the 6 months they say it will last up to.

I also used some Jobe's tomato spikes (which are 8-24-8 but no calcium) and Miracle Gro water soluable tomato fertilizer (which is 18-18-21 also with no calcium).

After I realized that I should use something with calcium unless I was sure there was enough in my water (I have no idea), I switched to Dynamite Mater Magic (5-5-9 plus calcium) and since that was so expensive, I ended up with Tomato Tone (3-4-6 plus calcium). I added it to the soil and mixed it in some, but not much because of the roots.

What I do now is dissolve 1 TB tomato tone in a gallon of water and then pour that on the plants once a week. Add another TB to the mulch on top of the containers and water that in every 2 weeks or so.

What is the best fertlizer for container plants? I have to water them a lot because they are in black pots and it gets hot here in Florida.

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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Don't know that there is a "best". There are many, probably 50 different brands, that will work just fine and you already named some of them. Otherwise you can easily get 50 different "I swear by ________" recommendations. ;)

Some prefer granular additives, some prefer liquids, some slow release, or granular plus liquid or foliar spraying or compost based or worm castings, or seafood or fish oil or etc.

Any of them as long as they also provide micro-nutrients will do the job. More important than type or brand IMO is the frequency of application because, as you say, nutrients wash out every time you water and too many don't understand that and so UNDER-fertilize container plants.

But most all commercial potting mixes contain lime to balance the pH of the peat and that lime is your calcium source and usually sufficient.

Enjoy your soon to-be-ripe tomatoes you posted about in your other post. Many of us envy you greatly. :)


    Bookmark   February 21, 2011 at 6:02PM
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tomncath(St Pete Z10a Heat 10)

...I switched to Dynamite Mater Magic (5-5-9 plus calcium) and since that was so expensive....

I'd say that's correct, are you close to Sarasota and how big is your garden? Might be worth your buying a 50lb bag from Florikan at $1.80/lb vs. $5/lb for the 2lb jar.

    Bookmark   February 21, 2011 at 6:42PM
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that is good to know about the lime added for pH.

I will be envying you come this summer when it gets too hot for us to grow tomatoes here!

    Bookmark   February 21, 2011 at 10:33PM
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not too close to Sarasota - I am in Bonita Springs. My "garden" consists of 5 containers in a court yard. I will have to measure them to know how big they are.

    Bookmark   February 21, 2011 at 10:39PM
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I do some hydroponic indoor gardening, formulating my own nutrients. So I simply use my "spent" Hydroponic nutrients in my outdoor garden as well as my house plants. The MG 18-18-21 is probably your best value as it is the most concentrated. I don't have the MG tomato formula on hand but I have the MG All Purpose 24-8-16 (I use it on my lawn). It contains sufficient amounts of Boron, Copper, Iron, Manganese, Molybdenum, and zinc. If MG 18-18-21 has these, you will only have to add Calcium, Magnesium and Sulfer when they become depleted from the soil which could take a very long time, The best way to add these for a potting soil application would be lime & Epsom salt. I don't recommend using fertilizers all the time with container gardening as these mineral salts can build up to toxic levels in the soil rather quickly. But back to the original question. Best Fertilizer for Containers? If they are outdoors my answer would have to include an occasional mulching with good organic compost.
Good Luck

    Bookmark   February 22, 2011 at 12:18AM
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The build up - that was a reason I was switching to the Tomato Tone and Mater Magic - I thought they would be less likely to build up salts in the soil since they are organically derived. I don't know if I am correct about that or not.

    Bookmark   February 22, 2011 at 8:54AM
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I have the same question as I have never gotten a single fruit from a container plant after three years of trying.

I'm growing two containers this year. The one I've used for the past three years is in a home made, self watering 5-gallon bucket setup. This year, I'm adding a commercial, free standing upside-down hanger. (Hey, it was 15 bucks)

The soil I'm using is the Miracle Grow Potting Mix with moisture control that is supposed to feed the plants for 6 months. I've also added Tomato Tone. I might throw in some of the Job Tomato spikes listed above as well.

Last night, I ran across a box of Epsom Salts and expired calcium tablets under our bathroom sink. Is this type of Epsom Salts OK or is there a special "Garden Variety" of Epsom Salts that I should use. Can I use the calcium tablets to add calcium to the soil (ground up, dissolved in water)? The plants I'm growing are Roma in the 5-gallon and Japanese Black Trifele in the upside down hanger. Since both of these are susceptible to BER, I want to make sure I get plenty of calcium early.

    Bookmark   February 22, 2011 at 10:04AM
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I have had terrible luck with Epsom salts when I have used it in the past on my roses in the ground. It burned the plants. I guess I used too much but my experience using it on roses in the ground was so bad that I would never dream of trying it in containers.

    Bookmark   February 22, 2011 at 3:22PM
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tomncath(St Pete Z10a Heat 10)

Hi Archerb, we're in different zones but I can't grow maters here in Florida except in containers due to nematodes....


    Bookmark   February 22, 2011 at 7:53PM
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billgill(Atlanta 7)

Tom, love your pictures love your place. Just had to say it.
Can I be you. Ha. :-)
I grew up in south Fla, brought back a lot of memories from the 50's.

    Bookmark   February 24, 2011 at 2:39PM
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I am growing in 7 Earthbox self watering containers right now and am growing a variety of vegtables. Have Early Girls in Water Walls planted in early February. Growing like weeds fight now coming out top of the Water Walls now. I bought Soil Mender Raised Bed Mix for these 7 which has rock minerals, coir, organic top soil, composted cotten burrs, humate, natural diamaetous earth. This is all in one mix Now as far as fertilizers I will not use commercial fertilizers at all. They are harmful to plants for all the reasons you mentions too much salts. I mix my own using this formula 4 parts seed meal(alfalfa meal, 1/4 part agricultural lime (fine ground), 1/4 part gypsum (or double the lime), 1/2 part dolomitic lime, plus for best results 1 part bone meal, rock phosphate, or high-phosphate guano, and 1/2 to 1 part kelp meal (or 1 part basalt dust). This is all you need for an all around organic fertilizer. Plants grow like crazy and it will not burn the plants. Most of these can be bought at your farm stores in bulk and at far more reasonable prices. I also spread some dry molasses on top of soil with the fertilizer which is also a natural fertilizer that increase biological activity in soil. It kills out fire ants too. For a foliar feeding I buy a gallon jug of Garrett Juice Plus. It has all organic compost, fish emulsion, liquid molasses, seaweed. I spray this every couple weeks on the leaves and drench the soil with it. Here are a couple links you might like, and

    Bookmark   March 6, 2011 at 11:14AM
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After some research as to what farmers and the pros and market gardeners use I think Calcium Nitrate is one of the main fertilizers they use for tomatoes. I just bought a 50 pound bag of it for $14.13 plus tax, and intend to use it to foliar feed my plants this year, I am guessing it will help prevent BER.

Here is a link that might be useful: Yara calcium nitrate

    Bookmark   March 6, 2011 at 11:42AM
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my tomatoes leave turned to dark green color and don't grow much, what is the possible problem? they were nice and green when I planted them in my 5 Gal. containers,

    Bookmark   April 13, 2014 at 1:22AM
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seysonn(8a WA/HZ 1)

Because containers are watered more often and are shallower and smaller in volume, some good portion of the nutrients go down the drain (literally). For that reason two methods are more suitable, IMO.

1- fertilizing with a weak fertilizer solution (like 1/4 rec. strength, water soluble) more often (Maybe every other time)

2- mixing in CRF to your potting mix before potting. That is how and what MG does and says it (plants grown in their potting mix) won't need fertilizing for up to 6 months. That might be an over blown claim but there is some truth to it. And CRF is responsible for that property .

One more thing: Use a CRF that also has calcium in it. I am using MG "Shake n Feed".

From time to time I also use MG "all purpose" water soluble (the one used in sprinkler type feeders)

So, there are many ways. It is hard to say what is "BEST".

    Bookmark   April 13, 2014 at 1:49AM
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