Poor pollination can keep your squash from producing. This guide is about zucchini rotting on vine.
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Here are questions related to Zucchini Rotting on the Vine.
Why do my Zucchini rot after the blossom drops off? They never get to picking size?
Hardiness Zone: 7b
By Marjorie C. Woodworth06/18/2009
My zucchini has produced only one 6 in. zucchini in the last month. The plant seems to produce flowers and I have tried to pollinate them myself for lack of bees in our area. However, the fruit that comes onto the plant starts getting soft at the tip once they are about 2 in. long. I used to have good success with this plant. Please help.
Hardiness Zone: 9a
By Eddie from Redding, CA
Why are my fruit rotting when they get about 2 inches long and yes they are rotting from the flower. I can't understand it. In the past they have been fine. Any suggestions?
By Jack K
By David M.08/08/2013
Sounds like Blossom End rot. Your soil is lacking calcium. The easiest way is to add crushed egg shells to your soil around your plants. I actually grind my eggs shells in a coffee grinder before adding to my plants. It takes a while to work, but it works wonders.
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Q: Am I the only gardener in the US who doesn't have enough zucchini squash? I planted four zucchini plants in my raised-bed garden, thinking that they would produce plenty for my small family. The plants have grown well and are quite large, but have so far only produced about 10 squashes this whole summer (this is a total count, not 10 from each plant).
Most of the flowers seem to fall off before they get pollinated. Any suggestions? I live in Albuquerque, NM, so plants get plenty of sun, and I water them regularly.
If flowers appear but you don't get much fruit, it's probably due to a lack of pollination. This sometimes happens if bee activity is low in your area or you've had a stretch of cooler weather. My suggestion would be to consider pollinating them by hand. The first flowers to bloom are usually the males and they do not form any fruit. The female flowers are identifiable by a swelling at the base of the flower. To pollinate by hand, you can cut off the male flowers, remove the petals, and rub the stamen of the male flowers against the stigmas (the sticky part at the ends of each pistil) on the female flowers. If you prefer, simply transfer the pollen from male flower to female flower with a small artists paint brush or Q-Tip. Keep track of which stems you have pollinated by tying a twist tie of piece of string around the stem. Also, make sure to harvest the squash when they are small (about 3-4 inches across and 4-6 inches long) to increase the plant's productivity.
By David Osinski
Hardiness Zone: 6a
Ray from Pittsburgh, PA
Spraying an antibacterial soap isn't necessary until your seeing signs of disease. From what you wrote, it sounds like the leaves and vines on your zucchini are fine (no signs of disease or insect problems), and it's just the fruit rotting on the vine that is the problem. Since your getting fruits, you must be getting flowers. This tells me you're probably just having pollination problems. Is the zucchini rotting from the blossom ends? When young fruit on healthy plants begin to rot from the blossom end, they are usually not getting pollinated properly. This can be due to a lack of bees in the area, or in your case, as a result of adverse weather conditions that may be keeping the bees away.
To get a successful zucchini crop, you're going to have to pollinate the fruit yourself. Pull off the male flower and pull the petals back to expose the pollen-laden stamen. Then carefully rub the male flower on the center stigma of the female flower making sure that the pollen makes good contact. The female flowers have a distinct enlargement directly behind their petals (this is actually the immature zucchini), while the male flowers are often smaller and attached to the vine by just a long, slender stem.Another method is to use a cotton swab to transfer the pollen between flowers. This way is more efficient because you can pollinate up to three female flowers with the pollen from one male. If the rot is starting on the underside of the fruit where it's coming into contact with wet soil, raise the zucchini off the ground with a sling made from pantyhose or prop them up using a tin can or small plastic container to keep them off the soil.
I have had poor success with growing Zucchini plants that produce Zucchini. There are ants in blossoms and many stems that do not produce zucchini. Should these stems be removed after blossom falls off? What else needs to be done?
Hardiness Zone: 9a
Carol from Stockton, CA
By Mark B
I used to plant 2-3 Zucchini seeds into each mound and thin the seedlings to 1 plant per mound, but recently, I've found that buying a partial flat of Zucchini plants from the local garden center is well worth the extra 2 or 3 bucks. You'll have a much earlier harvest, healthier plants, and longer growing season. Sprinkle a ring of slow release vegetable food around each plant when planting. Don't water everyday unless temps get above 90F. The large funnel shaped leaves of the Zucchini plant will channel any water that hits them directly to the base of the plant, and they also shield the soil from the sun, keeping it from drying out too quickly. Do this and you'll have more Zucchini than you'll know what to do with. Good Luck. Ed (07/29/2007)
By Mar Lynn
By Mar Lynn
Blossom End Rot is a disease common to Zucchini, which causes the blossom end of the fruit to rot. Per Clemson University, "The main symptom is a dark-colored dry rot of the blossom end of the fruit. Blossom-end rot is caused by a lack of calcium in the developing fruit." So either the plant is not absorbing enough calcium from the soil or the soil doesn't have enough calcium in it to start with. The solution is to get a PH soil test kit and test your soil. If it is lacking calcium, the solution would be to add calcium to your soil. Dolomite lime supplies calcium (Ca) as well as Magnesium (Mg) to your soil. It also increases the microbial activity necessary to break down nitrogen into ammonium for absorption by your plant's roots.
If the test shows the soil is okay, then you can increase nutrient uptake to the roots of the plant by mulching and adding compost or other organic matter to your soil (sheep, poultry, cattle, or pork manure has the best carbon to nitrogen ratio), and by watering well.
What causes yellowing in zucchini?
Yellowing is usually caused by a lack of nitrogen, which can be helped by adding nitrogen-rich compost, or by adding lime, or by adding manure. Many agriculture experts have advised amending soil with lime for nitrogen deficiency. There is an issue with organic fertilizers needing to be broken down by microorganisms in the soil before the plant can absorb the nutrients properly. The nitrogen gets "tied up" in this process and does not get absorbed by your plant quickly enough, so it's often recommended to use an inorganic nitrogen application along with your organic fertilizer. Again, the best solution is to do a soil test so you'll be able to eliminate what it is "not".
If the carbon to nitrogen (C:N) ratio of the organic fertilizer is less than about 20:1, "then microorganisms will obtain adequate nitrogen for their needs and will convert the excess organic nitrogen to ammonium (NH4+). This conversion is called mineralization." Ammonium is a form of nitrogen plants can absorb. Carbon acts like a furnace or energy source to speed this conversion process. Sheep, beef, swine, or poultry manure supplies the necessary ratios; speeds up the microbial process; and gets the nutrients to your plants.
A common practice in vegetable gardening is to broadcast lime and other amendments onto the garden soil and mix it well into the dirt and let it rain on it a number of times before planting your plants. In the old days, people didn't test the soil. They always just added the lime as a rule of thumb (right along with the 10-10-10) and they usually had a gorgeous garden. But you can achieve the same proper soil balance without the chemical fertilizer by using organic fertilizers, such as liquid fish fertilizer, complemented by rich compost and organic matter to speed mineralization. (09/13/2008)
By Lee H
I would like to know why my zucchini plants look great with lots of flowers and fruit but when the zucchini get about 3-4 inches they start to rot or go soft?