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Old June 6, 2014   #1
Delerium
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Default Any tips to get flowers to set in temps over 90F?

Do you have any tips to get tomato flowers to set when temps reach 90F and up?

I usually go outdoors in the mornings with the electric toothbrush and try to get them to set. Not sure if it actually works but i see the pollen just flying off the flower when i use the sonic toothbrush. But not sure how effective that is. I know that a shade cloth will bring the temps down a bit, would that help with having tomato flowers set?
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Old June 6, 2014   #2
heirloomtomaguy
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For sure i am just about ready to shade my plants. It will help with setting fruit. This cali heat is killing us this year.
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Old June 6, 2014   #3
Worth1
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Yes it will.
misting the plants at the right time may help also.
I just don't know what the right time is.
Be reminded that you need to vibrate the un opened flowers as well as tomatoes many times set fruit or pollinate before the bloom opens.

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Old June 6, 2014   #4
Dewayne mater
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I'm not so sure that 90 is the number. I think it is more like 93. Also, a factor, how cool does it get at night and what is the humidity? If you cool into the 60s at night, low 90s are not a problem in the day, especially if shaded during the hottest part of the day.

Perhaps less effective than the tooth brush method, yet less of a time eater is to somewhat vigorously shake the plants twice a day, morning and evening, for 10 seconds or so. This has seemed to help me, particularly when it is still and the wind aided pollination is nil.

Dewayne
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Old June 6, 2014   #5
b54red
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Water, water and more water. I found out by accident that basically over watering the plants during very high heat times makes a huge difference and mulching with a material that keeps the ground cooler. I use a blend of cypress mulch and apply it fairly heavily because it helps retain soil moisture as well as keeping the ground cooler because it doesn't transfer heat well.

The only problem with over watering is if the plants have large tomatoes or near mature tomatoes on them. Doing the heavy watering til I get a good fruit set can cause any existing mature fruit to be bland and to split. If I have a large older plant that really needs to set some fruit I pick off anything near mature and let it ripen on my porch so I don't damage them with the heavy watering.

Try it on one or two and I think you will be surprised at the results. Really soak the ground under the plants and then do it again in a day or two until you start seeing tomatoes set.

Bill
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Old June 6, 2014   #6
Stvrob
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Concentrate your toothbrushing efforts to those days following overnight lows which got down into the 60's. Make several rounds if you can in mid morning before the temps get hot. For me, overnight lows below 70 are becoming sparse from this date forward because of the higher dewpoints, but you might be fine in CA.
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Old June 6, 2014   #7
feldon30
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Quote:
Originally Posted by b54red View Post
Water, water and more water. I found out by accident that basically over watering the plants during very high heat times makes a huge difference and mulching with a material that keeps the ground cooler. I use a blend of cypress mulch and apply it fairly heavily because it helps retain soil moisture as well as keeping the ground cooler because it doesn't transfer heat well.

The only problem with over watering is if the plants have large tomatoes or near mature tomatoes on them. Doing the heavy watering til I get a good fruit set can cause any existing mature fruit to be bland and to split. If I have a large older plant that really needs to set some fruit I pick off anything near mature and let it ripen on my porch so I don't damage them with the heavy watering.

Try it on one or two and I think you will be surprised at the results. Really soak the ground under the plants and then do it again in a day or two until you start seeing tomatoes set.

Bill
With the hardpan red clay around here, I thought I would not need to water as much as I had in Houston. I was wrong, and my tomato plants are a bit mopey looking as a result and are just generally behind schedule. Today I totally went over the top watering everything and will be upping the amount of time I run the soaker hose.
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Old June 6, 2014   #8
Larry0150
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Quote:
Originally Posted by Worth1 View Post
Yes it will.
misting the plants at the right time may help also.
I just don't know what the right time is.
Be reminded that you need to vibrate the un opened flowers as well as tomatoes many times set fruit or pollinate before the bloom opens.

Worth
Hi Worth.

Have you ever used misting? I was going to try it for cooling a small area to see if it helps at all.

Larry
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Old June 6, 2014   #9
b54red
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Feldon I totally soaked my beds two days ago and went out today and checked under the mulch and the soil is barely moist. It got to 96 today and is forecast for just as hot tomorrow. I still haven't gotten over this crud so watering is really a chore now. Hopefully I will wake up before daylight and get out there and start watering early or I'll never get it done before the heat gets too bad. My later plantings are not generally setting as well as the first bed I planted because of the heat and dry conditions. According to the forecasts we have probably seen our last nights below 70 for quite a while so keeping the plants well hydrated is even more important for fruit set. Even my first plants still look like they have a while before I will be dealing with ripe fruit so I'm going to pump the water to them for now and get as much fruit set as possible.

Bill
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Old June 6, 2014   #10
aclum
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Hi,

Really interesting responses.

Worth, I'd be interested in hearing more of your ideas on misting. I recall you mentioning perhaps setting up a system a while back - something on a timer to go on at intervals during the day. I'm sort of wondering if you might rig up something with the misting directed at something other than the plants themselves - perhaps some sort of loose weave cloth that would pick up the moisture and somehow cool things down. (I'm "thinking" swamp cooler - but I really don't know much of anything about them so I need to do some research). Thinking about how you might cool things down with misting without increasing the spread of fungal diseases, etc.

Delerium, I wonder if (as an experiment) you used your agribon material as a shade cloth and, using the garden hose with a mist nozzle, sort of sprayed some cold hose water over the top of the agribon. Would it cool things down more than using agribon alone without any misting?

Also, I think it was either BrokenBar or CaronaBarb who mentioned passive cooling using the chimney effect. The warm air under the cloth should rise and flow out a vent at the top of the shade cloth.

Anyway.... just some somewhat OT musings about maybe cooling things down (not much help on the actual pollination in high heat issue, I'm afraid).

FWIW, in terms of keeping plants cooler here are some of my stats for today:

Wunderground official temp: 95
Temp in direct sun in the garden: 110
Temp under Aluminet Shade Cloth - suspended thermometer 5' above soil: 102
Temp under Aluminet Shade Cloth at on Silver Mulch (soil level): 85
Temp 5" deep in soil: 80

I don't know the details, but I think root temperature has some effect on tomato health, etc. and assume it might also have some effect on pollination .

Anne
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Old June 6, 2014   #11
carolyn137
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Quote:
Originally Posted by Delerium View Post
Do you have any tips to get tomato flowers to set when temps reach 90F and up?

I usually go outdoors in the mornings with the electric toothbrush and try to get them to set. Not sure if it actually works but i see the pollen just flying off the flower when i use the sonic toothbrush. But not sure how effective that is. I know that a shade cloth will bring the temps down a bit, would that help with having tomato flowers set?
I read the thread and saw what others have suggested and will add the following, whch I recently posted in another thread here.

There is no magic number above maybe 85 and above where pollination is inhibited. What happens with high sustained heat is that the pollen gets denatured ( destroyed), thus is not viable. All the sonicating and whacking plants with a broom and shaking plants is not going to help if the pollen is not viable.

How long for high sustained heat before denaturation sets in? I've tried to research that and didn''t get anything definitive but got the impressionn that just a few days can do it.

Another question I tried to research was whether all pollen had the same exact structure or whether different varieties had slightly different pollen structures so that some varieties might set better than others in those conditions, While I didnt find anything definitive, again, there are those varieties out there that are supposed to be more tolernt than others to heat, so I think it's possible that they might have pollen of a slightly different structure, one less able to be denatured. Then there are those who have posted that those vareties werent any different than those not said to be heat tolerantl

And I'm making the assumption that where you grow your tomatoes the humidity is usually low. And that's important since those who grow in hot areas with high humidity have a double whammy since with high humidity pollen clumps and is less effective

The only way I know of to avoid blossoms setting fruits in high heat areas is to start seeds in mid to late Dec and get them out by late jan. early Feb before high heat sets in. At least that;s what some of my friends in high heat areas do and it usually works for them .

Today I got yet another e-mail from Tomatmania in CA and I guess b/c quite a few years ago I was invited to Hortus Nursery in Pasadena, now out of business, to do a dog and pony show about heirloom tomatoes, and Tomatomania plant sales are now held at many different sites in CA, especially SOCal and about all I could do was to cut and paste what they wrote under the heading of " Second Wave:

(Start another garden section, a new row or a new pot! Or replace those that well, didn't fare so well?

Planting new seedlings now (or again) in SoCal and other garden regions with long growing seasons helps extend your harvest and back up that first planting, some of which should be fruiting in short order.)


Hope that helps,

Carolyn
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Old June 7, 2014   #12
MrBig46
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I read that pollen keeps its germination when stored in the refrigerator. Has anyone tried this pollen to pollinate tomatoes in times of high temperatures?
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Old June 7, 2014   #13
saltmarsh
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In August of 2011 I planted 7 Peron Sprayless tomatoes with the intent of trying to overwinter them in place using a modified cold frame.

As frost approached I covered the frame in 6 mil clear plastic and installed a remote thermometer with a soil probe which allowed monitoring the soil temp, temperature 2' above the ground and temperature 6' above the ground.

With the cold frame closed and the sun shining when the outside temperature was 70 degrees the temperature inside the cold frame quickly rose to 134 degrees (the max the thermometer could record.).

To solve this problem, I installed a thermostat controlled vent fan which started venting at 75 degrees and stopped at 70 degrees.

Heat during freezing weather was provided by an electric oil radiant heater.

This worked well and I started harvesting tomatoes on the 26th of December and had fresh tomatoes through the winter and spring of 2012.

In March of 2012 I started preparing a garden at a new location and power was removed from the cold frame. By this time the tomatoes had grown into the top hoop section and started growing back down to the ground.

Inspite of total neglect (no water, fertilizer, or insect control) they continued to make tomatoes until August of 2012.
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File Type: jpg Coldframe 11-7-2011 002.jpg (191.2 KB, 226 views)
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Old June 7, 2014   #14
ScottinAtlanta
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Here is a business plan for someone: Harvest good pollen, and sell it by the vial to those us in high temp areas. When ours is denatured, we crack open the vials.
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Old June 7, 2014   #15
b54red
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Carolyn, I live in an area where the double whammy of heat and humidity is constant from May til late October. I have definitely found that some varieties will set better in those conditions than others. I try to set out more of those varieties that set better in the heat as I do my latter plantings in hopes of getting some fruit in late summer and early fall when the high temps are usually relentless with few rain breaks to cool things down for a while. We have now reached that time when nights almost never get below 70 and days are usually in the 90s and above so from now til fall it will be much tougher to get a good fruit set.

Anne, I agree that keeping the soil temperatures lower can really have a positive effect on fruit set. Since I started using the heavy layer of cypress mulch I have had better luck with fruit set during those really trying times and it has the added benefit of keeping soil moisture much more even.

Bill
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