Why are my squash and zuchinni plants so pale green?

Question

I have one zucchini and one squash plant growing vertical in planters. They seem to be very healthy. Lots of male flowers open and blooming. Dozens of other flower buds. I don’t see any females yet, but I know the males always come first, to attract the bees. They are growing but much slower than the rest of the garden. I planted them using Miracle Grow planter soil in 48 quart pots and left them in the soil from the container they came in from Bonnie Plants. The soil seems to stay very damp, in these containers. It does rain in Eastern South Carolina, pretty much daily, in June so I can’t tell if the always damp soil is poor drainage or just lots of rain. I don’t water them at all. The rest of my garden is dark green and lush, even a Baby Bellafina and two different types of tomatoes planted in the exact same type of container with the exact same Miracle Grow soil for containers. They do have just a few white mildew looking spots, but only a few and the soil gets this white film on top of it, every few days. I just till the soil around them by hand and it disappears. I figured that is just because the soil stays damp? They look perfect otherwise, just growing slow and very light green to yellowish. Only the leaves on bottom are dying as the plant rises up (naturally). The soil is supposed to feed them for six months, so I am afraid to put more fertilizer in there, in case it is just an iron deficiency. I don’t want to burn them with too much fertilizer and that soil is supposed to have everything they need. (The paper cups around their bases, have the bottoms cut out, they just go around the bases to keep Vine Borer moths from laying eggs next to them). Any help is appreciated!

Answer 1

That looks quite healthy! Since it is pretty evenly green, and the lower leaves are what is dying off first, I would suspect that there is a pH imbalance, and that it can be regulated by a sprinkle of dolomitic lime and iron sulfate.

This will supplement calcium and magnesium (which I suspect are lacking… This is common in container) along with iron and sulfur. All of this together will help regulate the pH, as well as add the most common deficiencies back to the soil.