Fertilising Tomatoes in Pots

[TomatoGirl]

Seeing as I can only grow my tomatoes in pots (5 gallon to 8 gallons pots), I'd really like some good advice on what fertiliser to use, as well as how frequently to fertilise. I realise with the smaller pots that the nutrients will get depleted faster, and was wondering if fertilising with a soluble fertiliser (miracle grow 18-18-21 for tomatoes) every week would be too much or just right?
I have been using some fish agra and compost tea, but it really wasn't enough for them.
Right now they all have flowers and some even have baby tomatoes. They have only had one feeding with inorganic fertiliser and I noticed the change in them after a few days. My plants had been pretty yellow looking after an accidental overdose with aspirin water, and on the advice of members here, gave them a good feeding.
I'm just trying to get the feeding on a good schedule where I am not over or under feeding.
When they were planted I added crushed eggshell to the pots, but was wondering is it would be an idea to purchase some calcium nitrate. I had way too much BER last year, and am hoping to avoid that this year if possible. Growing in pots means lower yield, so losing some to BER is a real bummer.
I welcome any advice. Thank you

[imafan26]

Tomatoes are heavy feeders but I would back off on high nitrogen fertilizer now that they have started to flower. I would give them a1/4 cup of tomato tone now and repeat once a month now that they are flowering and fruiting. I would have preferred larger pots to hold off BER. A SIP pot would be better. It is not the calcium in the soil that matters but the transport system. BER is caused more by irregular watering than by lack of calcium. Tomatoes have a very large root system so they need a large soil volume and consistent moisture. I use 18 gallon pots for tomatoes or a self watering planter I made from an 18 gallon rubbermaid tub. 5 gallon SIP buckets were too small for indeterminate tomatoes but o.k. for the mini varieties like patio.
https://www.postoilsolutions.org/documents/Earthbox.pdf

Mulching the pots will help conserve moisture as the plants get larger you will have to water more than once a day. Some varieties of tomato are more prone to BER than others. I grow heat tolerant tomatoes and rarely have BER. The large tomatoes have more problems with cracking and BER than smaller tomatoes.

[Allyn]

I just learned recently that when growing tomatoes in containers, sometimes it isn't necessarily about inconsistent moisture that can cause BER. You do need consistent moisture for the tomato plant to take up the available calcium, but if the soil is too warm, no matter how consistent the moisture and how much calcium is in the soil, the plant won't take it up. If this is the problem, adding more calcium to the soil won't help. I really had a hard time with the tomatoes I grew in 5-gallon SiPs this year and one variety was a heat-tolerant variety. I had more BER than I had good tomatoes from them and I know it wasn't a moisture problem. The soil in the small containers was getting too warm. That may not be your problem there in Canada, but it's something to consider if your pots are getting overly warmed sitting in direct sunlight. It's easy to heat up that small amount of soil.

[TomatoGirl]

Sorry for the late reply!!
We don't have tomatotone here in Canada, so I have been using miracle grow for tomatoes. I have been giving it to them once a week as well as giving them fish emulsion once a week and watering every day. It has been pretty hot some days, and on those days I have watered twice. They have a lot of flowers and fruit, and as of right now I've not seen any BER. Everything seems to be in good balance at the moment, so I'm not going to change anything. I'll keep watching out for the BER. I purposely got the lightest pots I could, so hopefully the roots don't get too hot. Was thinking about adding some mulch to the top.

[TomatoGirl]

They have got very tall in the last couple of weeks.

[applestar]

It's possible you could back off on the fish emulsion now that they are fruiting...?

[lakngulf]

Miracle Gro was the ticket for your plants. They look so healthy and green tomatoes look great. Good job.
I try to get my container plants some fertilizer about every two weeks, but I have held off in these hot hot days of July.

[AnnaIkona]

It's possible you could back off on the fish emulsion now that they are fruiting...?

Why so?

[applestar]

Fish emulsion is usually considered a nitrogen source. What do the NPK add up to between the two fertilizers? MG tomato is formulated for tomatoes intentionally with lower N.

[TomatoGirl]

I believe the MG is 18-20-20 and the fish emulsion is 5-1-1
I'm adding the fish emulsion as organic nutrients rather than a fertiliser.
I gave 6 other people tomato seedlings this year, and mine seem to have the most flowers and fruit and the plants are really healthy, so I don't really see a reason to stop doing what I'm doing. They are feeding heavily right now and the fact my pots are fairly small and I'm watering a lot so the soil gets depleted fairly fast. If I start having problems with them I will consider changing what I'm doing, but for right now I couldn't be happier with them. So I'm not going to mess with what I'm doing.

[TomatoGirl]

Miracle Gro was the ticket for your plants. They look so healthy and green tomatoes look great. Good job.
I try to get my container plants some fertilizer about every two weeks, but I have held off in these hot hot days of July.

Thank you. I'm very happy at the moment. I was recommended to fertilise every week as my pots are on the smaller side. It seems to be working well so far

[imafan26]

Realize that if you are trying to do organic in pots especially with a heavy feeder like tomatoes it will be very hard to get a big plant. NOP calculated the minimum volume of soil needed for the soil to support any plant organically would be 26 gallons. Otherwise, you would have to feed the plant and not the soil. It is hard to give a large plants like tomato enough organic food in a pot for it to do well. There simply is not a large enough population in a small pot to support the microbes and a plant.


I don't have a lot of issues with BER. Variety does make a difference. I grow mostly heat tolerant varieties. I don't know how hot it gets where you are but my tomatoes will do fine as long as the temperature stays below 90. I don't add dolomite to my soil and I use citrus food that contains micros and slow N. My tomatoes don't wilt in midday unless I forget to water them. I have only encountered BER on an heirloom tomato and that was because it was not heat tolerant.and the plant wilted a few times in the heat. Temperatures above 90, Heatwave II will stop setting flowers. I tried to grow some of the Florida heat resistant tomatoes but they don't have resistance to the other diseases here and did not do well.

The tradeoff for more disease resistance unfortunately, has been taste. I am not really fussy about tomatoes. I don't care if it is a little bland, as long as it is not mealy.

[imafan26]

I would second that you need to back off on nitrogen now that the plants have filled out. Otherwise you will have growth at the expense of fruit.