Saturday, June 16, 2012

Zucchini Plant Problems: Help! Yellow Leaves, Yellow Fruit. What is wrong?

Growing Zucchini in Container: Zucchini Plant's leaves and fruit turning Yellow

My zucchini plant use to be the star of my garden. I started it from seed about a month and a half ago and now it is easily the biggest plant I have. It is in a 5 gallon container with a soil manure mixture. I water it daily for about 20-60 seconds. Lately I've noticed that the larger leaves are yellow. I had small zucchini coming it. It was so cute and green, but it stopped growing and turned yellow.

This is my yellowing zucchini plant:

Night View:

New healthy zucchini growing in:
Poor small pollen deficient yellow zucchini:

The Diagnosis

There are two direct problems with the plant. 1.The yellowing of the zucchini plant's leaves points to nitrogen deficiency. 2. The plant is not being pollinated. I will first address the nitrogen problem.

Zucchini plants are heavy feeders and crave the vital NPK nutrients. N stands for nitrogen. Nitrogen promotes leave growth and vegetation. P stands for phosphorus which promotes root and shoot growth. K misleadingly stands for potassium which promotes flowering and fruiting.

Since my zucchini plant is in a pot it has quickly drained all the nutrients out of the soil manure mix. This is an important lesson for first time container growers. Since the plant has a limited supply of dirt, you must replace the nutrient with fertilizers routinely.

To organically, quickly, and effectively treat my zucchini plant I'm giving it bat guano. Mix about a tablespoon into 1/4 gallon of water (I use an old Gatorade container). Watch as the leaves transfer from yellow into a nice healthy green. Wait 3-4 days and repeat if the leaves are not the desired color. You can see the progress of the zucchini plant as it turns from yellow to green after it's treatment here: zucchini plant treatment

Now I will address the pollination problem. If your zucchini looks like the picture below then it has not be pollinated and you will have to manually pollinate the plant.
Zucchini plants have both male and female flowers.

This is a picture of a male zucchini flower's stamen, which holds the pollen:

This is a picture of a female zucchini flower's pistil, which collects the pollen. The easiest way to decipher an male zucchini flower from a female zucchini flower is that the female flower will be attached to a zucchini vegitable:

To pollinate the female flower use your finger or a q-tip to collect pollen from the male flower, then wipe it on the female flower's pistils.


  1. Thanks! When I transplanted my zucchini from a one gallon to a 3x3 I built, it was so root bound. Zucchini don't do so well in containers. They really overproduce huge fruits in the ground. One day...Maybe my landlord will let me tear up the dying grass for a front yard garden!

    1. Front yard gardens for all! I want to sneak veggies into peoples yards when I see them water their silly grass.

    2. I prefer little to no front yard, a house pushed up near the road. That way you get a bigger back yard for a garden. Front yard gardens I've seen make the house look cluttered and quite unappealing to the eyes.

    3. This was wonderful advice. I have zukes that started getting yellow leaves and I kept looking for borer beetle signs, but there aren't any. So this is something I can fix. I love bat guano, but hadn't found any locally. I will website it and see if someone has it in my region. Thank you again for the advice. I am going to keep your site in my bookmarks.

  2. I find pollination is even more effective with a small (clean) make-up brush.

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  4. I have had this problem with my zucchini now for the last three seasons. I use to grow huge plants with wheel barrows full of squash, now I get yellow, stunted rotten four inch ugly squash. I will try the pollination and add more nitrogen. If this works I am a follower for life. Thanks, Ron Weatherman, Chewelah Wa

  5. I went to your blog first when I searched why my zucchinis are turning yellow. Thanks! I just need to fertilize the darn thing more often, because I hear it getting pollinated all the time by the neighbor's honey bees. Luckily I already planted in a 5 g. pot.
    By the way it is a bush baby variety more easily grown in a container, for those of you that also container garden.

  6. I planted zucchini in 18 gal. tubs , they produced tons of zucchini . Fertilize every 5 days and water daily . one advantage I have is that there are bees all over the backyard . Every morning I watch them do there thing , my little helpers . Plant some flowers between them if possible. If you see a praying mantis in your yard , catch it and place in on the zucchini plant . It will stay and eat the bugs that invade the zucchini, ( I have photos of this ) ........awesome .

  7. Fertilize every 5 days?! With what? I have new raised beds (3 feet by 8 feet) with purchased "topsoil". I added peat moss before planting but the plants have done poorly. Mostly yellow leaves and over half of the fruit rots off. Even slugs got into the new soil.

  8. Check the ph of the soil, too much peat might make it too acidic. Ph of 6.5 fits into the range of almost every vegetable. Bonemeal and consistent moisture helps prevent end rot.

  9. It depends where you are, I'm in North Italy and every time I plant zucchini they grow beautiful and good, and I don't add anything in the soil, except cow manure in the Fall.

    1. I agree, it does depend on your climate and growing in healthy soil.

    2. well cow manure is the nitogen the plant needs, Others that dont have cow manure may need to use organic nitrogen or chemical nitrogen

  10. My leaves are great but the fruits (which some are huge) are yellow and I'm very sure I didn't buy yellow squash. ????


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