It looks like this will be the week that temperatures finally warm up for good along the Front Range making it safe to plant the warm-night loving vegetables. If you've been able to walk the tightrope between maintaining transplant condition while keeping them indoors at night and outdoors to harden on decent days, versus planting in the garden because they are too big, congratulations.
For those who have managed transplants to hold for planting this week, the warm nights above 50 degrees F should promote rapid establishment and growth. If you had to transplant last week or earlier, your plants may sit stunted for a while until they recover. Unfortunately this adds days to harvest to your tomatoes, peppers and other warm season plants.
While frost danger appears to have passed in Denver on May 2nd (31 degrees F), the night temperature was 33 degrees F on May 16. Although mostly in the forties and a few high thirties since then, it was still cold to think about setting out squash, peppers, tomatoes, eggplant and others.
Fertilizing transplants to keep them in good condition was helpful as long as this didn't cause too much new growth. A fully soluble vegetable fertilizer that contained phosphorous as well as nitrogen helped avoid purple backs to leaves, a sign of phosphorous deficiency.
Some plants that ran out of fertilizer could be turned around by fertilizing as these tomato transplants have been.
Photo credit: Fertilizing transplants, Phosphorous deficiency on tomatoes, Tomatoes turned around with soluble fertilizer - All Carl Wilson