Is there such thing as TOO MUCH sun?

[NewGardener2013]

Hi everyone

I live in Melbourne, Australia and we have really random weather. We have been getting a scorcher 40 degree day about once a week or so, and the sun just burns. I have been putting a shade cloth over my little veggie patch on those really hot days to try and shelter it a bit, but I'm wondering if I should even do that?

Do you think the plants can withstand really hot and sunny weather, and I should just let them be, or should I keep doing what I'm doing?

Thanks!
Jess

[applestar]

Short answer is it depends on the plants. It also depends on how long the sun exposure is, and much water they are getting.

Some gardeners in Texas, Florida and other hot regions build shade houses over their vegetable beds, which are like green houses except covered with shade cloth.

So, whatcha growin'?

[NewGardener2013]

Hmmm ok then. I am growing snow peas (which for some reason just don't want to play ball), beans, cherry tomatoes, cucumber, celery & beetroot.

I am also about to plant carrots, radishes, sweet corn and lettuce...

[gumbo2176]

Hmmm ok then. I am growing snow peas (which for some reason just don't want to play ball), beans, cherry tomatoes, cucumber, celery & beetroot.

I am also about to plant carrots, radishes, sweet corn and lettuce...

What you mentioned all like sunlight. Lettuce will bolt and go to seed once it gets hot. To prolong its growing season, some resort to shade cloth or planting it among larger plants that will shade it. Right now, my lettuce is doing quite fine in full sunlight for up to 11 hours a day, but the temperatures are quite mild and not above the low 70's this time of year. I live in New Orleans and that is in U.S. Zone 9.

What's your weather like this time of year as far as average temperatures?

[gumbo2176]

Don't know how I did it but I completely missed your first post about how hot it is right now. My experience is tomato plants suffer a lot in very hot weather-----to a point that I simply pull them and wait for milder temperatures to re-plant. I put in 2 crops of tomato plants a year with the first in late Feb. to early March and the second in by early Sept.

The ones planted earlier in the year are usually finished by mid July and are suffering with our daily heat.

One crop I grow that loves heat and is drought tolerant is Okra. If you like the stuff, try it. Be aware that it is a pretty fast growing plant that can grow to 7-8 ft. tall but likes being planted fairly close. I generally plant them where there is no more than 18 inches between plants.

[rainbowgardener]

You need to pay attention to what individual plants need:

"I am growing snow peas (which for some reason just don't want to play ball), beans, cherry tomatoes, cucumber, celery & beetroot.

I am also about to plant carrots, radishes, sweet corn and lettuce..."

Peas, carrots, celery, and lettuce are cool weather crops, which may not sprout or at least will not do well in hot temperatures (40 d C = 104 d F = HOT!). It is summer where you are, so you need to concentrate on summer crops.

Cool weather crops: peas, carrots, celery, lettuce, spinach and other greens, broccoli, cabbage, potatoes, beets and other root crops.

Warm weather crops: pretty much everything else including tomatoes, peppers, squash, melons, okra, corn, basil, eggplant.

But realize that temps over 100 F are stressful for most plants. In that kind of weather, they will need lots of water and probably some shade.

[digitS']

Your post here encourages people in the northern hemisphere to think about mid-summer heat:

Giant Heatwave Delivers Hottest January on Record, The Sydney Morning Herald

. . .Peas, carrots, celery, and lettuce are cool weather crops, which may not sprout or at least will not do well in hot temperatures (40 d C = 104 d F = HOT!). It is summer where you are, so you need to concentrate on summer crops. . .

Steve

[soil]

The answer is yes.

It's called the light saturation point. It's when the light increases photosynthesis to a point where basically the co2 the plant produces as a byproduct is being produced faster than the plant can deal with it so photosynthesis sort of shuts down until better times.

This is why tomatoes and other veggies look like there doing nothing mid summer.

Now like said it depends on the plant when this happens. this is why polyculture farming is superior. Let's say mr tomato is growing great it's startingbto get hot which will shut things down, but here comes the dappled shade of let's say a corn plant. This lowers the available blistering intense sun for maybe even only 20-30 minutes. Which gives the tomato the ability to continue producing and growing all day. Where otherwise it would be light saturated and put on hold.

[tomc]

Hmmm ok then. I am growing snow peas (which for some reason just don't want to play ball), beans, cherry tomatoes, cucumber, celery & beetroot.

I am also about to plant carrots, radishes, sweet corn and lettuce...

Radish, lettuce, peas, celery, beet root may need your cool season for plant out.

[NewGardener2013]

Thanks everyone - all of this help is most appreciated!

[rainbowgardener]

Love this place! I still learn new things here all the time. I never heard that term light saturation before. Thanks, soil!

[cynthia_h]

Definitely provide them with shade. Tomatoes will shut down and wait for cooler times when temps rise above 95 deg F (35-36 deg C), so give them what they need--shade and, possibly, water.

Cynthia H.
Sunset Zone 17, USDA Zone 9