Q&A: Should we be planting summer or fall veggies right now? (mid-July)
It feels like the dead center of summer. It’s hot. It’s humid. Some plants are loving the long days and others are struggling or even fully succumbing to the stress of heat, drought, pests, and disease. You may have lost a zucchini to the dreaded Squash Vine Borer, or walked out to your garden one morning to see an entire cucumber vine totally wilted, thanks to a bacteria carried by the Striped Cucumber Beetle. Ugh.
To be honest, we would not blame you if you wanted to ignore this whole situation for a couple of weeks and come back to gardening when the weather cools off. But if you do happen to have some reserves of hope and energy and are ready to jump back on the hobby horse, you might be wondering “What can I plant in those empty spots? Is it too late late for summer veggies? Surely it’s too hot for fall veggies?” The answers come when we layer two gardening concepts on top of each other: “days to harvest” and “days to frost.” Lost? Excited? Let’s break it down.
Days to harvest: Each species and variety of plant has a typical lifespan programmed into its genes. “Days to harvest” written on a seed packet or plant tag refers to the number of days from planting a seed (or transplanting a seedling) to when the crop is ready to be harvested. This number is an estimate, and is based on ideal conditions, but can give you some good information to choose plant varieties and plan out your successions of crops. For example, if you live in a cold climate with a short summer, you may want to choose a tomato like “Glacier,” which is listed as 55 days to harvest, over “Beefsteak” at 96 days. Or maybe you’ll be out of town for a couple of weeks 55 days from planting time, so the longer-season crop is your pick.
Days to frost: Based on historical records, we can estimate when our area will get its first frost of the season. Typically for Middle Tennessee, we use a date near the end of October as as our estimated date. So “days to frost” refers to the number of days remaining from now until the first expected frost of the season. Knowing this number requires math. Doing new math every day. Or Googling or asking Siri. How annoying! I made a little button on my phone that tells me the number since I’m planting all the time, and here’s how you can too.
This information is critical for gardeners because frost can damage or kill most all summer plants, so it’s a date we need to keep our eye on as it approaches.
Sooooo back to the original question: Should I be planting summer or fall veggies now? Let’s figure it out.
In mid-July, in Middle Tennessee we’ve got about 100 days until our first frost. That’s so much time! There are tomatoes that ripen in 65 days. Green beans in 55. Summer squash in 45! Cucumbers, okra, and some heat tolerant greens can also be great candidates for a mid-summer planting date. Note that these are all plants that are happy in warm and hot weather.
And remember the “days to harvest” number refers to ideal conditions. As we start to get into August and September, daylight lessens and plants grow more slowly. So even though the calendar might say you have 55 days to harvest, it’s pretty risky at that point to plant a cucumber and expect to get a good harvest before frost. Often folks will add 20 to the listed “days to harvest” to account for shortening days and to give time to actually enjoy a good harvest from a plant. In other words, if your cucumber plant tag says it will be ready in 55 days, plant no later than August 10 to give the plant 75 days to mature. And even then, we could always get an unusually early frost that kills the plant, so it can be risky. This is where you need to know your own risk-tolerance and make decisions based on what you are willing to lose.
What’s it too late for? Using the +20 formula above, we can only choose plants that are listed as 80 days to harvest or less. This means we are past the window for pumpkins and other winter squash, most melons, and certain varieties of tomatoes and peppers. If we plant them now, frost will likely kill these plants before we can harvest from them.
But what about radishes? Lettuce? Aren’t those ready in just 30 days? Yep. But they like cool weather. It’s still too hot for them. What’s great is that they can typically survive light frost, especially if we cover them, so we will wait until temps cool off to start planting those. And we don’t have to do quite as much math since that frost date won’t be the final farewell.
For most home gardeners, who either start seeds directly into the garden or buy transplants from the garden center, that’s all you need to know.
But it’s worth thinking about the fact that in order for those fall seedlings like broccoli, cabbage, and spinach to be ready for sale in September, they are being started in cooled, shaded greenhouses right now. If you want to go next level and start your own fall seeds indoors, now is the time. One of my favorite tricks this time of year is to sow a flat of cilantro microgreens to grow inside where it’s cool. I can harvest these for my salsa in August and then save a few clumps of the seedlings to transplant into my garden in September.
