Manipulating Tomatoes To Force Blooms During Summer 'Cold Fronts'

Okiedawn OK Zone 7July 12, 2009

Most of the time I try to garden as naturally and as organically as possible, and most of the time it works out just fine.

So, for normal years, I feed the soil and let the soil feed the plants. That works well too, although it is harder to achieve with container-grown plants since the heavy watering they require often leaches nutrients out of the soil. I avoid the high-nitrogen chemical fertilizers because they tend to give you foliage at the expense of the roots and fruits. When you see someone who has huge, lush, green tomato plants with simply gorgeous dark green color in June and little to no fruit set, you can almost bet their plants have too much nitrogen.

When the weather turns up the heat early like it did this June, folks in our part of the country often have great difficulty in getting their tomatoes to set fruit even if they have been very careful to avoid excess watering and excess nitrogen. This is caused, of course, by hot weather and high humidity. Most years you cannot do a lot about it, especially if you're in a part of the state where the nights do not cool down very much. (This year, that would be a huge portion of the state.)

Sometimes, though, in the midst of these heat waves, we have a "cold front" come through like we did a couple of weeks ago. During a summer cold front, if that cold front drops your daytime and nighttime highs back down low enough (below 95 for daytime, and anywhere below about 92 is perfect, and below about 75 at night), you probably will have additional blooming and fruit set on your tomatoes.

So, when we knew the most recent cold front was coming, I went to Lowe's and bought Green Light Super Bloom which has an N-P-K of 12-55-6. I could have used the Miracle Grow Bloom Booster with its N-P-K of 15-30-15, but I REALLY wanted to encourage bloom and fruitset, so I went with Green Light's higher P formulation. Did it work?

You betcha! We had a very heavy fruit set that was beginning to break color as the cold front approached. Since we'd had a very hot summer after the initial fruit set in May, I was desperately hoping for more blooms and fruit and knew the coming cold front was our "best chance". Therefore, I fed the plants the Super Bloom about 3 or 4 days before the Cold Front arrived. I think, if I had done it 5 or 6 days before the Cold Front arrived I might have had even better results. However, I'm happy with the results I've seen. We had lots of blossoms and I am seeing a lot of small new tomatoes, so the manipulation seemed to help.

Was it necessary to feed the tomato plants a bloom booster? Nope. I just did it as a little extra insurance. We would have had "some" blooms and fruit set without the bloom booster, though likely not as many.

If another cold front approaches this summer, I'd try it again. The so-called cold front that is expected here in Love County about Wed. or Thurs. won't cool us down enough---we'll still be in the mid- to upper-90s, but at least we won't be in the 100+ temperature range. So, I won't try it this week, but if you are further north and the cold front is going to take you down to the right temps, it might be worth your while to try it. Do it sooner rather than later for the best results. You should feed your tomato plants (I fed my pepper plants too with the same results on the hot peppers) a few days before the cold front arrives, so the food has time to 'force' new blooms that will be able to set fruit when the temps are cooler.

And, no, I did not do it in a scientific way...feeding half and not feeding half so I could compare the results because I wanted to feed them all. The number of blooms/small tomatoes I'm seeing since the feeding/cold front, though, have convinced me it worked.

Ever since reading Dr. Meisner's Giant Tomato book, I have pondered the idea of using a bloom booster, although growers of giant tomatoes use it in spring to encourage early and large flowers. I used it at a different time to encourage mid-summer fruit set that is hard to achieve here.

You also could use a bloom booster to get good fruit set on your fall tomatoes when the first 'cool spell' of fall is coming and your fall tomatoes are ready to set their first fruit ever.

And, for your tomato newbies, it is the larger-fruited tomatoes, the type we use for slicing, that have fruit set issues in hot weather. The ones that produce really small fruit like grape, currant, cherry and small pear sized ones set fruit all summer long. Most paste tomatoes also set well all summer long. A select few of the ones that produce smallish tomatoes (bigger than Large Red Cherry, but smaller than Early Girl in mid-summer) like Livingston's Gold Ball, Fourth of July, Porter, etc. also don't slow down much in the heat. The ones the Bloom Booster help with are those like Better Boy, Jet Star, Primetime, Supersonic, Goliath, Black Krim, Brandywine, Cherokee Purple, Chocolate Stripes, Nebraska Wedding, Royal Hillbilly, Brandy Boy, etc.

And, if you are in a low-humidity area, and especially a low-humidity area where the nights still dip into the 60s in the summer, you may not have the fruitset issues. I think the lower humidity helps fruit set. In years when Love County is in severe drought, I often get fruit set on large-fruited tomatoes in August when the daytime highs exceed 105 and the nighttime lows are in the 80s. The difference? Very, very low humidity. One of my best tomato years ever was in 2003 when we only had 18" of rain (and 1/3 of that fell in May) but the low humidity allowed great fruit set as long as I kept watering.


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I also am a fan of Green Light Super Bloom - plus I use a bloom set spray early in the mornings occasionally. Our temp here today is 109 - so I doubt anything will encourage the blooms to set for a few days. I've used the GL Super Bloom on tomatoes, peppers, and even squash and cucumbers with good results - much better than just the Miracle Gro for tomatoes. Hopefully it will cool off for all of us soon.

    Bookmark   July 12, 2009 at 8:03PM
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Okiedawn OK Zone 7

I hope it cools off for you too.

I usually go totally organic and fertilize with liquid fish emulsion and liquid seaweed, but I couldn't resist trying to manipulate my tomatoes into blooming during a cold break in a heat wave.

109 is too hot! We were a measley 102 here today and that was way too hot for me.

All my other stuff blooms just fine without any help, but I'll give tomatoes all the help I can.

I'm going to try shading some of them with aluminet next year. I toyed with the idea of doing it this year, but hadn't ordered any and hadn't come up with a way to erect it over the plants before it got too hot way too early in June, so I have it on the "To Do" list for next year.

I'm just excited it worked. The tomatoes that set last week are the ones we'll be harvesting in August, which is usually a pretty dead period here. Now, all I need is another cold front with temps in the right range before the end of July to set some fruit for September. If I am going to dream, might as well dream big! : )

    Bookmark   July 12, 2009 at 8:43PM
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I used some bloom booster this year also, for the first time ever. Next time I will pay more attention to the weather before I use it. Thanks Dawn, you make me consider things that I hadn't thought of. I'm probably a third grade gardener. LOL

    Bookmark   July 13, 2009 at 12:19AM
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Okiedawn OK Zone 7


You're welcome. \

I don't think I normally need a bloom booster because I think the plants do fine on their own in a normal year. (I wonder if anyone here can describe a "normal year" in Oklahoma. LOL)

But, you know what, I thought it was worth it to try and encourage blooms to set while the weather was 'just right' and I'd do it over again given another chance. Since it is mid-July, though, I doubt we'll have another "cold front" here in southern OK this summer that will drop the temps low enough for fruit to set. Well, we might have one in September!

I desperately need to go outside and pick tomatoes for a couple of hours, but I pulled a muscle in my back yesterday and can barely sit, stand or walk, so I guess my gardening today will be limited to sitting on the sofa with my laptop computer and "talking" about gardening. It is going to be a long hot day so I guess this is as good of a place to be as any.

I suspect, by the way, that if I regularly used chemical fertilizers, I could manipulate the tomatoes into heavier blooms earlier in the season, but I'm afraid it might create more of a fruit load than the plant could carry well, and that could encourage Blossom End Rot. So, I guess I'll stick to Tomato-Tone most of the time. Still, the Bloom Booster experiment seemed to work in this case.


    Bookmark   July 13, 2009 at 7:58AM
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caroline_2008(Z 6)

I too am a long time user of S B. Started

using it way back about 20 plus years ago.

I used it on my flowers more than on veges.

A friend told me about it , and she used it.

I bought my first S B in Wall Mart in Colorado.

I am ready to pick ripe tamotoes, I got them started

late, too much late cold and too much rain, now it is

a droght, Had a huge grass fire here in Major Co.for

the last 3 days. Got it under control last nigt.


    Bookmark   July 13, 2009 at 10:40AM
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Okiedawn OK Zone 7


Hi! I saw the news about your fire in Major County on the first day and hoped it wasn't in your part of the county. I really feel for all the firefighters and support personnel who were out in that weather. Fighting wildfire in normal summer conditions is brutal enough as it is, and the weather y'all have had lately takes "brutal summer weather" to a whole new level.

I really haven't used bloom booster type fertilizers on flowers or veggies since I went organic a couple of decades ago, although I'll use them in extenuating circumstances like I described in this thread. I also used MG tomato fertilizer in 2007 to kick start the tomatoes after all the heavy spring rains. By the time the soil dried out they looked so pitiful and I felt like they were "starving", so used the MG and it helped them a lot.

I'm glad you're ready to pick the ripe ones. After a few weeks of a heavy fruit load, I am starting to get tired of them. LOL I am NOT tired of eating them, but tired of all the work in picking fruit from 80+ plants, dehydrating, freezing and cooking them. Sometimes I walk into the kitchen and look at the bowls full of tomtoes everywhere and wish they weren't there. Then, I get over it and get on with "putting food by" for winter because I know I'll miss the fresh ones when they are gone and will be thrilled to have the preserved ones.

I am really dreading having to dig potatoes soon, though, and think it is just too hot this month for digging potatoes! Because we had 12" of rain in one day here at the end of April and it drowned most of my potatoes which had been planted at the proper time, I had to start over with new seed potatoes in early May, so mine are very, very, very late. I've never had to dig potatoes in such heat and am not looking forward to it at all.

Everything is producing late this year in comparison to other years, but at least the plants are producing. Even the flowers look about as well as could be expected considering the heat, but then I plant only really heat-tolerant and drought-tolerant types anyway.

Hope y'all soon get a break from the heat there.


    Bookmark   July 13, 2009 at 11:52AM
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I with the MG bloom booster about ten days ago on around half the plants. I did it first to give the plants a boost and then hoping it would start some to blooming. Think I was a little late. The blooms really started about the time the heat set in. Afraid they may be about over by the time it cools down. I sprayed the other half with the tomato feed. I feel both gave them a boost. I don't usually use them much but if weather conditions are tough and due to stress or whatever they aren't taking up what they need it seems to help. I wish I had some more bloom booster to spray with again. It really kicked the True Black Brandywine into gear. Just hope some will set. Jay

    Bookmark   July 13, 2009 at 12:32PM
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Dawn and Jay,
We're supposed to have what could loosely be described as a cold front move in about Thursday of this week. I think I will give the bloom booster a try myself, today, if I can make it to Lowe's.

So, far I've just used Tomato Tone, but admitedly, I've been tempted to use a bloom booster as I have in the past because it always seemed to help, not just with tomato's but with anything that has a flower or bloom. Wondering about Watermelons and Cantaloupes too. I think my watermelons are lagging behind in foliage, although their blooming. The Cantaloupes are outstripping them in both bloom and foliage growth. I am a bit disappointed because I was so looking forward to a big watermelon harvest. Three of the plants aren't doing well at all due to some tree roots I think. I have all these trellised, but am thinking of pulling the three runts and replacing with some other vining plant that doesn't require such heavy feeding. (off topic a bit, sorry).

When it cools off a bit Thursday, (hopefully), that's the time I plan to set out some more young tomato plants. Do you think it would be advisable to give these young plants a pinch of Green Light Bloom Booster to jump start them?


    Bookmark   July 13, 2009 at 12:54PM
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