BuddingGardens
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Trouble with SunFlowers :(

Hi there!

My name is Tracy and I'm posting on behalf of my dad (he's not very computer savy) who loves to spend time in the backyard planting stuff.

I did some rehab and release on a squirrel that found it's way to our home last year and he and all his squirrel friends are now visitors in the backyard. As a result we found that planting sunflowers was a fun thing for them. We had some success with our fist couple of plants (the bugs scarred me a bit but I got over it quick enough). We did notice a problem, and it has continued even though we switched to black oil sunflowers (he happened to have that variety)

Here are some pictures that better describe the issue.
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I told him that I think is related to overwatering, but he swears he isn't overwatering.

imafan26
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Location: Hawaii, zone 12a 587 ft elev.

It looks like a fungal problem. Sunflowers like to be in full sun and the ones in the picture look like they are planted in at least some partial shade or getting shaded by other plants. Plant them in full sun and space them so they will get good air circulation. Mine are about 3-5 feet apart, but I plant mammoth, Lemon Queen, and Chianti.

The sunflowers are nearly done as they have already started to bloom. I would cut off the infected leaves or pull the plants to keep the fungus from spreading. Fungicides can be used early but, it looks like it is past that now.

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applestar
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In my garden, sunflowers steadily lose their lower leaves. I just cut them off as they become unsightly or dry up. If most of the leaf is healthy green, I might simply trim the bad part from the leaf with scissors. I just think of it as routine clean up.

HoneyBerry
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I agree, those look like shade-grown sunflowers.
I love shade-grown sunflowers for fun. They don't get very big. They are cute yellow flowers. I have them under my tree, under the bird feeder. The birds drop some of the sunflower seeds and they grow under the tree but don't grow tall.

BuddingGardens
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Awesome thank you all so much for the quick replies.

He had them near our pool which was been drained for a while now and he thinks mayve the algae from the pool water might have caused some issue.

I'll be sure to pass the note on about full sun!

imafan26
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Location: Hawaii, zone 12a 587 ft elev.

Probably not the algae from the pool. Algae and fungi are biologically different. Rust and fungal problems are common with sunflowers that get wet and don't have the time to dry off. In fact most plants with gray green, hairy leaves are actually designed to be grown where there is less water. The color helps protect them from the sun and the hairs on the leaves and the spines on cactus capture and hold on to water that is usually in the form of dew.

It is very adaptive in dry climates and in rainless summers.

BuddingGardens
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The rust and not letting the flowers properly dry sounds like it might be part of the issue!

I know the ones that we had that were in full sunlight did tend to do better than these. Also I saw you mentioned you had planted mammoths in the past, were they much more difficult to take care of? We plan on just using them for seeds for our squirrels and birds

imafan26
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Location: Hawaii, zone 12a 587 ft elev.

Mammoths are not any harder. They get taller and I have to stake mine because of the wind. They can get up to 8 ft tall and it is also why I usually space them around the garden about 3-5 ft apart. If you are growing sunflowers for their seeds, mammoth has the largest seeds and the most germ. The heads attract a lot of bees and other beneficial insects but I still do not get all of the seeds to fill. The birds will raid the heads for the seeds unless you cover them.



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