Plants, like many Humans, have affinities toward "cool" and "warm". "Some like it hot, and some like it cold..." They not only like it best but they do best in either warm or cool (hot or cold). In fact, it may well make a difference in surviving or not.
If they are cool season plants, they thrive when soils and air temperatures are cool. This could be either the spring or fall depending on their unique cycle. Cool season plants get baked in the hot season. They bolt and go into seed production. "We gotta get out of here. Time is short," you can almost hear them say. The gardener watches them shrivel and fade as we go into the hot season. You can almost see them go into heat prostration. I know some humans like that too. Examples of cool season plants would include: pansies, peas, lettuces, green onions, radishes, potatoes, chamomile, cilantro, asparagus, crocuses, tulips, daffodils.
Warm season plants just love the heat: "Bring it on." Warm soil and air temperatures just make them happy. You can almost feel them wiggle with joy as their roots go deep, their leaves are healthy and vibrant, their flowers bloom in profusion (if it is in their cycle), and look at that fruit (or roots). Examples of warm season plants include: tomatoes, squash, peppers, melons, cucumbers, okra, sorghum cane, roses, zinnias, marigolds. And don't forget the sweet potatoes. They just sit there if the temperatures are not to their liking.
Planting warm and cool season plants out of their special time is a ticket guarunteed to bring in the opposite of what the gardener intends. The plants just sit there. They are stressed. They are more vulnerable to pests and diseases. And sometimes they just wither and die.
As a gardener, we get pretty eager in the spring. "Now slow down, Honey," the Earth seems to say. We used to be tempted to put plants out sooner than it was their time. Experience taught us that is extra work for the gardener, which is not our cup of tea.
April 25 is the last frost date in these parts based on "past data". We can still get frost and it still can be cool, but the chances are increasingly remote. On or about May 10 is usually a marker for safely planting warm season crops. We head to the garden with our rafts of tomatoes, peppers and the like. I have been waiting to plant those sweet potatoes until about June 1. It seems more apt to suit their facy.
Again, all of this is based on "past data", which was a pretty accurate predicter. Note the word "was". Times are changing. Of course, we could always expect subtle variations of weather that were outside the frame, but they were usually quite limited. With climate change, we are seeing more and more extraordinary weather events including temperatures.
The recent warm record breaking warm temperatures can tempt the gardener to plant warm season plants too early. We forget that the cold can come back, which it is supposed to the next few days. Tomorrow's low is predicted at 34 degrees. I found 35 degrees on NOAA and I like that a little better.
Unusual temperatures do put the gardener in some kind of dilemma. "When on Earth should I plant anyway?" Are the warm temperatures here to stay? Should I plant half of my warm season crops (including plants and seeds), knowing full well that I could lose them?
Our letter carrier said he planted tomatoes this weekend. He said he would be covering them over the coming days. I suggested he might want to put coats on them. For us, we are resisting the urge, knowing that the ground is still cold. It is a risk no matter how you look at it.
The rules are changing. And the gardener needs to be ever sensitive to those rules and the fact that s/he isn't quite sure what the new rules are. In the meantime, we have all of our plants for transplanting inside (except the leeks and the cabbages). They may come inside too. They had all been outside these past few days and they were luxuriating in the moderate to warm temperatures. I must say however, that the 3 gardeners who reside here (and probably the plants too) were more than a little confused at the weather outside the "frame".
On this night, I must not forget the Rosemary. This little potted "shrub" will not be happy if the temperatures dip outside her range. If something happens to her, I won't be happy either.
And so it goes, out here on the Farm. I suppose that similar stories are being written these days by anyone who grows food.