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I need help with growing healthy watermelons  RSS feed

 
Donna Bowen
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I need help with growing some healthy watermelons.   They always have, end rot!!  This Georgia red clay dirt may be the culprit, what do I need to do??
 
Joseph Lofthouse
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My strategy for dealing with blossom end rot is to plant a number of varieties, and then save seeds only from plants that don't get blossom end rot. Then only grow seeds from my own plants and never save seeds from a plant  that gets blossom end rot.

 
James Freyr
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Blossom end rot is generally a symptom of a calcium deficiency in the soil. You may likely need to add a calcium supplement. Sometimes deficiencies occur when the root structure of a plant can't grow far and wide to reach the nutrients in the soil. Improving your soil with some quality compost will aid in growing healthy watermelons.
 
William Schlegel
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https://www.ces.ncsu.edu/depts/pp/notes/oldnotes/vg19.htm

Add calcium this article from North Carolina says.

I tend to add my eggshells to the household compost. Last year I added left over oyster shell from chickens long past to the tomato garden. I didn't know watermelons got it and that the solution was the same. Article says lime might help too.

I add sand as a surface mulch to my clay soil in Montana for growing cantaloupes and watermelons. I would be even more interested in biochar if I had red dirt. Biochar is a humus substitute and soil is red when there is no black from humus or charcoal to cover up the iron in highly weathered soils. So I would add compost, biochar, and sand in layers on the surface. Since they recommend calcium I would amend with lime and maybe some wood ash. If I wanted more than a small patch of melons and couldn't afford soil amendments I would sure be looking for a watermelon variety that was less prone to the problem as Joseph suggests. Blossom end rot certainly varies in tomatoes- Romas seem to get it easily.

 
Joseph Lofthouse
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Location: Cache Valley, zone 4b, Irrigated, 9" rain in badlands.
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My general sense of blossom end rot -- across species -- is that it's more common in oblong fruits than in round fruits. It's more common in large fruits than in small fruits. So if I were choosing a watermelon variety to trial in an area prone to blossom end rot, it would be a round fruited variety with smallish fruits (3 to 6 pounds).

 
James Freyr
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Blossom end rot is a symptom of deficiency. It knows no boundaries from plant varieties or species. Granted some cultivars may prefer more available calcium over others, but your plants are telling you something is not balanced with your soil. The soil may either truly be deficient in calcium, or, there is plenty of calcium, but it is unavailable for the plants roots to uptake and use. The latter can get complicated, as other factors like soil pH, the soils' cation exchange capacity, and levels of other nutrients get involved in the equation. A soil analysis will give you the data you need to decipher what your plants are saying. I have dealt with blossom end rot on tomatoes in the past and if I apply a liquid chelated calcium, the problem ceases and the new tomatoes forming don't exhibit symptoms. Adding calcium will never undo or make existing fruits exhibiting blossom end rot improve. I personally would never lime a soil to correct a calcium deficiency, especially since the wrong king of lime can be applied, making things worse. It's entirely possible to have two different soils with a great pH of 6.3 but sample one has a % base saturation of calcium of 63% and magnesium of 15% and the other, sample two, have 43% calcium and 32% magnesium. The first sample has a much better Ca:Mg ratio for soil and plant health, the 2nd sample's ratio is way off and unhealthy. If one were to apply dolomitic lime to sample 2 to try to increase calcium levels, things will not improve. So, you can blindly add a chelated calcium supplement and improve the fruit quality and reduce blossom end rot symptoms, but in the long run, soil testing and getting ratios in balance will bring about overall better soil and plant health. Hope this helps
 
Marco Banks
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I recently read a long study on biochar (posted on this site) that talked about biochar's ability to work with plants to inhibit various diseases, end rot being one of them if I'm not mistaken.

Healthy soil leads to healthy plants.  I also have heavy clay soil, but years of mulching with a thick layer of wood chips twice a year has made a huge difference.  I don't use a ton of biochar throughout the garden, but after reading this article, I'm convinced that it might be a good idea to begin incorporating it more aggressively.  The problem is producing it in sufficient quantities.  So since I can't treat the entire garden with lots and lots of biochar, I can at least make sure it's represented as a significant proportion of my potting mix.

So I've been putting more and more biochar into my potting mix.  With a base of sharp river sand, a couple big scoops of my normal clay-y garden soil, lots of well-finished compost (at least 50% of the mix) a generous handful of Azomite, and a couple of cups of finely pounded biochar, my potting mix gives the new plants a healthy start.  I don't buy expensive stuff like perlite -- no need to.  I innoculate the biochar in a wet mix of compost for a couple of weeks before adding it to the mix.  When planting seeds directly into the soil (as you normally would with watermelons) a couple of handfuls of this potting mix might make a big difference.
 
Viola Schultz
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Location: Zone 6 Hudson Valley
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Joseph Lofthouse wrote:My general sense of blossom end rot -- across species -- is that it's more common in oblong fruits than in round fruits. It's more common in large fruits than in small fruits.


well, my limited observation is that BER is more common in a sauce tomato which tend to be oblong but also small-er.  I never had a blossom end rot on a Brandywine tom even tho I wasn't nice to it, at times. I did have a problem on a cherry tomato but I believe that was calcium deficiency and my inexperience.  I tend to agree that, eliminating problems with watering and/or calcium deficit, it is a DNA problem and I should start collecting seeds from the plants that are healthiest and deliver in my garden and under my sky.
 
K W-Schornak
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Multiple potential complications, having grown in Georgia clay:
#1: calcium: As mentioned above, you might have a calcium deficiency of some sort. You have a couple of options: get a good mineral supplement, or grow plants that "mine for calcium" such as dandelion, then using the plants as fertilizer/mulch (calcium isn't available until the plant decomposes).
#2: Soil texture: If it's truly HEAVY clay, you're going to need to shovel in some organic matter to loosen it up and as a result improve the cation-exchange capacity, as mentioned above.
#3: water retention: watermelons don't like too much water, or soil that doesn't drain. If you're having drainage issues, I suggest mixing a bunch of compost in with native soil, build it up into a hill, and plant in that hill, so the water doesn't puddle and weaken the plant to infection.
#4: soil pH: in Georgia, we tend to have acidic soils. If the soil gets too acidic, it can hinder the absorption of calcium. Get your soil pH tested, and add limestone or ashes as needed.
 
Walt Chase
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Location: ALASKA
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BER is generally caused from a deficiency.  Have your soil tested and amend as needed. Don't go adding stuff willy nilly in hopes of getting it right, just have a sample tested.  GA has an awesome Ag Extension Service tied in to UGA.  Get with your county agent and he/she can help you out.  Let your county agent know you are growing "organic", if you do, and they can make recommendations for the amendments for you. My wife's great-uncle used to grow several acres of watermelon in good ole red GA clay so its not the clay per se'.
 
Steve Day
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Watermelons get there needs met by the root system going deep in the ground. Try digging a really deep hole like with a post hole digger or a power auger as deep as you can or feel like. 2 to 3 feet seems good to me. I'm not an expert.  Fill back with what you took out or mix with whatever seems right. This is a deep subject. Sorta like the joke about lawyers why when they die they are buried 50 feet underground. Because deep down they are nice people. (from a lawyers website) deep down your watermelon roots will like you more.
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