Yellowing pumpkin leaves is a somewhat common problem that can have lots of causes. Nutrient deficiency, lack of sun, disease and over watering are the most common issues. Trouble shooting the issue can be a challenge. Nutrient deficiencies are going to be typically one of three things: nitrogen, magnesium or iron. A nitrogen deficiency will typically show up as overall yellowing of the plant with slow growth. An iron deficiency will typically have yellowing leaves that start at the top of the plant. A magnesium deficiency will start with yellowing leaves on the bottom of the plant. To fix this, a foliar application with some fulvic acid (learn more) or humic acid (learn more) will typically solve the issue. However, you have to look at factors that are driving the issue as well. Over watering can cause issues with nutrient uptake, so if that is what is causing the deficiency then decrease watering. Lack of sun light can also cause similar issues because the plant can use the nutrients it has to do photosynthesis.
learn more) and fulvic acid in it. The plants have been a bit yellow for weeks because we've had almost no sun for the entire month of May. This morning I could see however that the situation had become worse. As you can see the bottom leaves are very yellow on the 1415 and 282 plants. So after doing the drench on all of the plants I did a foliar application of epsom salts and multi-mineral with some humic acid in it. I'm really, really looking forward to some sunny days, because if we don't start getting some sun I think I'm going to be having some real problems.