Oh avon, that has to be annoying.
interesting on the artistan well... I am surprised your grass doesn't fry in the sun.
as for spinach, try coffee ground soil. 2 cups coffee ground, 1 gallon soil (your choice), 1/2 cup sand and throw in some peat moss or wood chips to keep it moist throughout the day, this is per 2-3 spinach plant. Only put them out where morning sun will hit them and in the shade after 11 am your time. use COLD water as it doesn't stunt in cold water after they are 3 inches tall.
I grew a bunch of spinach last summer, even if it was humid and rainy. Broccoli, carrots and cauliflower are the same. If I were you I would try to start the seedlings in Sept-Oct time frame.