The Three Waves of Veggie Gardening

April 19th, 2022

   One of the keys in Nicole Burke’s “Kitchen Garden Revival” strategy is grouping different vegetables into their plant families.

This patch is a “Wave-1” planting.

   Nicole says that when she first started gardening, like so many other beginners, she was overwhelmed at the thought of how to grow the many different plants.

   Her “ah-ha” moment came when she realized that botanists long ago grouped plants into families by their similar traits and growing habits.

   Broccoli, cabbage, cauliflower, kale, and kohlrabi all fall into the brassica family, for example, while cucumbers, squash, zucchini, pumpkins, and gourds are sisters in the cucurbit family.

   “Instead of having to understand each and every plant on the seed shelf or every plant at the garden center,” Nicole said in a Great Grow Along webinar on her strategy, “you really only need to master a handful of plant families. Once you do, each time you want to grow something new, you simply find out which plant family it belongs in, and boom, you know almost immediately what season that plant likes to grow in and how well it’s likely to grow.”

   Nicole’s “Kitchen Garden Revival” book and her Kitchen Garden Academy online courses go into a lot more detail if this approach sounds interesting to you.

   I agree that anything we can do to simplify vegetable gardening will help beginners and encourage them to stick with it.

   The strategy that I gravitated to long ago was grouping plants by when they’re best planted.

   That boils down to just two basic groups – 1.) ones that grow best in cool weather and that can survive frost, and 2.) ones that grow best in warm weather and that will croak if hit by frost.

   In Pennsylvania’s climate, we have the growing-season length to support three main “waves” of plantings.

   Wave 1 starts in very early spring – around the end of March and into about mid-April.

   That’s the time to plant cool-preferrers, such as seeds of peas, radishes, lettuce and most leafy greens, spinach, carrots, beets, kohlrabi, radicchio, turnips, parsnips, and kale as well as onion sets, seed potatoes, and transplants of cabbage, broccoli, cauliflower, celery, parsley, and leeks.

   It’s important to get these in the ground when it’s still cool not only to take advantage of the growing time and space, but because most of these don’t do well once the weather gets hot.

   Radishes get hot and woody, for example, and lettuce turns bitter and bolts to seed if it isn’t in and out before daytime highs start hitting the 80s.

   Wave 1 gives us a lot to pick from, so it’s no wonder my vegetable garden has always been about two-thirds full even before we get to early May, when a lot of gardeners are just getting started.

   A few of the Wave 1 choices are so quick to mature that you can have a harvest in the books and bare space ready to replant by late May or early June. Radishes, leaf lettuce, and spinach are the three best bets for that.

This was a Wave-2 planting one summer in my old Hampden Twp. vegetable garden.

   Once we get past frost, it’s time for Wave 2.

   These crops are the summer ones, including seeds of beans, corn, cucumbers, melons, squash, okra, pumpkins, and collards, and transplants of tomatoes, peppers, eggplants, sweet potatoes, and basil.

   Our all-time latest killing frost in Harrisburg is May 11, which means that date is a good “safe-planting” milestone. However, frosts have happened north of Harrisburg and in outlying areas even as late as Memorial Day.

   On the other hand, our warming climate has been pushing the last-spring-frost dates earlier and earlier, so that now we often see our last frost around mid-April or so. While that timing will give you a few extra growing weeks most years, be aware that a later rogue frost can kill tender plants with just a few sub-freezing hours on a single night.

   What I do is get ready to plant Wave 2 crops around the end of April and then look at the 10-day forecast. If there’s nothing even close to frost on the horizon, I pull the trigger. If even sub-40 nights are in the 10-day forecast, I wait.

   A few of the cool-season preferrers are heat-tolerant enough that they also can go in the ground during Wave 2… or at least toward the beginning of Wave-2 time. Beets and carrots are the two best bets, while it’s possible to grow lettuce in warmer weather if you give it a little afternoon shade and keep the soil damp.

   I not only plant my Wave 2 plants in the space I left open while planting Wave 1, but I tuck them immediately into the open space as I harvest Wave-1 crops.

   Examples: yank the radishes and replant with peppers; yank the spring carrots and replant with beans; yank the peas and replant the trellis with cucumbers, and yank the cabbage and replant with zucchini.

   For me, planting vegetables is not a spring-only thing. I plant and replant – never letting any space bare – until I run out of maturity time on the back end of the season.

    This is called “successive planting” and is a great way to take full advantage of the space and hold down the weeds that otherwise would quickly move into bare space.

   As daylight dwindles and temperatures begin to back off between mid-August and the end of September, it’s time for Wave 3.

   Most of the Wave-3 crops are the same ones as Wave 1 – with a few exceptions.

   I’ve never had much luck getting peas or potatoes to do well in the fall, plus there’s not enough time or light to produce big bulbs of onions in the fall (if you can even find sets to plant then).

This is what my fall cabbage usually looks like after cabbageworms find it.

   Some people have good success with late-summer replantings of cabbage, broccoli, and cauliflower, but I’ve found that cabbageworms are much worse then than spring. I’ve tried protecting them with floating row covers, but I suspect that the combination of dwindling sunlight and the extra shade these covers cause is enough to stunt growth.

   My “go-to” late-season crops are lettuce, radishes, carrots, beets, turnips, and kale, plus August-planted Brussels sprouts, which are very cold-tough.

   I’ve even managed to sneak in a fast-maturing crop of bush beans planted in mid-August.

   Garlic can also be planted in fall to mature the following early summer.

   The trick with Wave-3 planting is knowing how long it takes each crop to mature, then planting soon enough to give plants a chance to get there before the shorter days and colder nights of fall end growth.

   Add at least a week or two to usual maturity times (listed on seed packs and plant labels) because crops mature slower in fall as conditions become less favorable compared to spring, when light and warmth are increasing.

   Not a lot of gardeners do a Wave-3 planting at all, but I think it’s time to rethink that since our changing climate is pushing back our first killing frost of fall.

   According to the most recent National Weather Service data, the median date for fall’s first freeze is now Oct. 21 for most of south-central Pennsylvania but Nov. 1 for Adams, Lancaster, and York counties. Harrisburg beat both of those last year.

   Most years, I still have a few last crops to harvest as late as Thanksgiving. With cold frames and similar covers, some people push the envelope even beyond that.

   Whether you like Nicole’s plant-families idea or my “wave-planting” strategy, take a shot at veggie-growing this year. I can’t say it’s quick and easy like so many books promise, but it is a healthy and rewarding thing to do.

   If you’d just rather see a list of what to plant when and how (i.e. seed or transplant), check out my “When to Plant Which Edibles” post.