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Spring: Season of Perennial Vegetables in the Cold-Climate Garden

Excerpted from Paradise Lot by Eric Toensmeier with contributions from Jonathan Bates

Bates and Toensmeier will be hosting a perennial vegetable tasting and edible landscaping workshop at their garden in Holyoke, MA, USA this April 26, 2014.

Jonathan Bates with spring perennial vegetables.

From the beginning of my interest in plants for permaculture and edible landscaping I identified perennial vegetables as a real gap in the available information. Nobody seemed to know what perennial leaves, roots, and shoots could grow under or between fruit trees, nut trees, and berry bushes. I spent a number of years accumulating information on the species which culminated in the publication of Perennial Vegetables in 2007. Since then I’ve presented many workshops for master gardeners groups, organic growers, and landscape professionals. Everyone seems shocked to learn that we have such a fine palette of long–lived and low–maintenance vegetable crops for cold climates. The fact that many of them are fine ornamentals is a lovely bonus as well.

In 2000 Jonathan and I ordered seeds of perennial veggie crops from some unusual companies, including the amazing French company B & T World Seeds, who offer more than 18,000 species and varieties. Seed packets and shipping were not cheap, but we only had to do once (thats the great thing about perennials!). We grew out the pants and transplanted them here to our new home when we moved in 2004. At this point many of them are ten years old and still going strong, producing leaves, broccolis, shoots, roots, and fruits.

After the long desolation of a Massachusetts winter, things start to move pretty quickly after the snow thaws. This is the season of perennial vegetables, and the time that their advantages over annual crops become very clear. In the time it takes to get annual crops ready to eat outside, we have already gone through three months of perennial vegetable harvest. At that point the perennials pass the baton to the annuals, having bolted and lost their flavor until the coming fall or spring.

In March as the snow melts the bedraggled remains of last year’s perennial vegetables poke out. Though there is some freezing damage on the leaf tips, baby greens are already coming up here and there throughout the garden.

“Profusion” sorrel.

Sorrel (Rumex acetosa) is a overlooked vegetable in most gardens. The sour leaves are typically good eating in spring but quickly lost to bolting and bitterness. We grow a non–flowering variety called “Profusion” that never flowers. It just keeps on cranking out fresh leaves all season long. Partial shade, drought, and even two feet of snow only seem to slow it down temporarily. Sorrel is a great example of a multifunctional permaculture species, because its deep roots concentrate nutrients from the subsoil. Calcium, phosphorus, and potassium accumulate in the leaves and are made available to neighboring plants over time as the leaves break down into the soil again. Sometimes we speed this process up by cutting back our sorrels and mulching with them. This also causes a flush of tender new growth. “Profusion” sorrel is also notable for the density of its growth. We planted a dense row of it as a barrier between two different types of ground cover and have had good success. Sorrel also grows very nicely in the greenhouse all winter.

Water celery, aggressive but abundant.

Like sorrel, water celery (Oenanthe javanica) pokes its head up early and has tender shoots waiting and ready as the snow melts. From now to the end of April these greens are among our favorite salads. Sometimes Jonathan and I get down on our hands and knees and graze on it like sheep. It’s parsley–celery flavor gets to be too strong by the end of May but boy are we happy to have it in March, and again in late fall. We have found water celery can be quite a weed in our water garden, so to keep it under control we have a patch in dry partial shade. This slows it down to the point that it often dies back completely in mid-summer.

Caucasian spinach, quite delicious.

Early spring is also the season of sprawling spinach shoots (Hablitzia tamnoides). Like a skinny asparagus with tender leaves, this is a high-class vegetable. Though we have had trouble finding the perfect location and conditions for it, one plant in somewhat moist partial shade has persisted about four years now. By April, shoot season has passed and the season of edible leaves has begun. These can be eaten raw well into June. Few perennial vegetables can compete with that lengthy season.

Sunchoke puts on dramatic growth.

March is not too late to harvest last year’s perennial root crops. Some, like sunchokes (Helianthus tuberosa) are at their absolute best this time of year. Sunchokes, also known as Jerusalem artichokes, store their energy as starch in their tubers over the winter, but as spring comes they converted to sugar in anticipation of the growing season. What is a decent vegetable in the fall becomes almost as sweet as apples in spring.

Tubers of groundnut.

We dig other root crops in early spring as well, like skirret (Sium sisarum), Chinese artichoke (Stachys affinis), and groundnuts (Apios americana). For many years I was not a huge fan of groundnut tubers. They seemed a second–rate substitute for potatoes. We still grew plenty of them, because they are native, high in protein, and fix nitrogen. But it wasn’t until I read Samuel Thayer’s The Forager’s Harvest that I learned how to deal with groundnuts in the kitchen. Thayer suggests treating them like the bean relative that they are. Following his advice, I mashed up some boiled groundnuts with chili spices and cheese as though they were refried beans. Suddenly this high–protein native crop had found its place in my diet.

Ramps, the wild forest leek of the eastern forest.

April comes and plants are leafing out everywhere in the garden. The absolute delicacy of spring for us is ramps (Allium tricoccum). This native wild leek grows in the shade of moist deciduous woods throughout Eastern and North America. I had always read about Appalachian ramp festivals where the whole town reeked of garlic for days. When we lived at Wonder Bread Organic Farm Jonathan and I decided to host our first Ramp Festival, a tradition we continued with for four or five years. This celebration of spring abundance brought friends with dishes like nettle quiche and Japanese knotweed crisp. Our friend Frank Hsieh brought all whole roasted spring lamb from his farm.

I had been keeping an eye on a patch of ramps across the street from a Subway the next town over for several years. My sustainable harvests had provided the ramps for many of our festivals. Then one year I drove by to visit the ramps and to my horror saw that a large condominium development was going in. I rounded up a crew from the ramp Festival and we rescued hundreds of plants. Today they and their progeny are growing in our garden (and many others as well).

Perennial scallions (Allium fistulosum).

Perennial scallions come into their own in April too. If you grow scallions from seed you can time the harvest to have them any time of year. That’s very nice but a bit more work than we had in mind. Every spring our Welsh and walking onions send up their new scallions. We dig or divide their clumps for harvest and transplanting. This glut of scallions is welcome after a long winter and put to use in fried rice and scrambled eggs. Fall brings a second flush of scallions which are welcome again.

Giant fuki at close to full size.

At the base of our bamboo, in the shade of a feathery–leafed mimosa grows a plant with enormous round leaves up to three feet across. This is fuki (Petasites japonicus giganteus), a popular wild edible in Japan and a very bold statement in the landscape. Not content to grow ordinary fuki with its eighteen-inch leaves, we obtained the giant form. I was pleased to learn that giant fuki is sterile and thus has no chance of dispersing into the environment. Besides, that is, it’s incredibly aggressive rhizomes. But our fuki is hemmed in by bamboo rhizome barrier on two sides and a frequently traveled for path on the other. We actually wish it would grow faster so that we could harvest more, because fuki is a favorite spring vegetable on both sides of our duplex. Like rhubarb, it’s the leaf stalk that is eaten, but fuki is more analogous to celery as a vegetable. We boil the stalks, peel them by hand, and marinate them in umeboshi or raspberry vinegar with some shredded ginger and tamari.

Some people balk at the labor involved in processing crops like fuki. To me I don’t mind spending fifteen extra minutes in processing a vegetable that took no work to grow since I planted it four or five years before. It’s just a question of whether you account for the labor in growing as well as cooking your food.

Good King Henry

April brings an embarrassment perennial vegetables riches just keeps coming. Asparagus, good King Henry (Chenopodium bonus-henricus), and giant Solomon’s seal (Polygonatum commutatum) provide tasty shoots. Even the tightly curled shoots of hostas can be cooked up this time of year, though I admit they’re not my favorite. But you’d be hard pressed to find a hardier vegetable for full shade. Violet leaves are usually fairly bland, but Dave Jacke introduced me to a cultivar called “Rebecca” which has remarkable vanilla–mint flavored leaves and flowers that are quite delightful. Another April favorite are the wasabi–like roots of the eastern native toothwort (Dentaria diphylla). This delightful groundcover has piquant horseradish-flavored roots and leaves. I’m convinced that a commercial producer could market the roots to the finest sushi restaurants.

Yum! Purple asparagus.

The king of cold–hardy perennial vegetables is asparagus, and around here May is the peak of harvest. We grow “Purple Passion”, and its fat spears keep coming for more than a month. Fresh–steamed asparagus is as good an argument for turning your lawn into a garden is anything I can imagine.

Sea kale broccolis.

When I first saw sea kale, I fell in love. Against the dark green garden foliage, the powdery blue-green sea kale called out, coaxing me in for a closer look. The purple hues of the new leaves added to the beauty. Although the tender spring leaves are edible, kinda like collard greens, our experience is that the plant adds only a half dozen leaves a year, and are the plant’s summer solar panels. Eating them would put an end to the plant in short order (an alternative is to eat some leaves in the fall after most of the growing has taken place). We have come to love not the leaves, but the early spring broccolis. Along with the first six to eight inches of tender new flower stalk growth, the broccolis, or “broccolitas”, can be eaten raw, mixed into salads, or lightly cooked with butter and salt, or added to a vegetable stir-fry. Outstanding.

From the beginning, Eric and I have experimented with hundreds of species of little-known plants. Like sea kale, many of the plants are perennial vegetables. A perennial vegetable being a plant that re-grows for three or more years, and has some part of it that is eaten like a vegetable. Like asparagus, sea kale broccolis are ready to pick weeks before most annual vegetables can be planted. Perennial broccolis like sea kale can be grown as permanent, low maintenance, early season vegetables. By extending the growing season in this way gardeners can grow delicious vegetables for more days out of the year.

Many of you reading this may ask why more people aren’t growing perennial vegetables like sea kale. One answer may be that a monoculture of annual broccoli can grow more calories, then a monoculture of asparagus or sea kale. But, what does it really take to grow broccoli these days? And how much soil is being eroded from all the plowing and cultivation? Not to mention the chemicals, fuel, and water it takes. From our experience perennial vegetables can be grown with a lot less labor and inputs, with zero soil erosion. Perennial veggies don’t fit the typical monoculture mindset, and our industrial, “turn a profit fast”, “economies of scale” food system.

When mixed with a diversity of other perennial vegetables, fruits and nut producing trees and shrubs, and grown in multistory polycultures, the minor yield shortcomings of sea kale fall by the wayside.

Because our sea kale has lived as long as ten years, we’ve been able to enjoy its flowering season every spring. Imagine an explosion of three-foot tall, snow white bundles of small flowers, filling the garden with a voluminous honey scent. Take that annual broccoli! It’s a fantastic bee attractor to.

Turkish rocket broccolis.

But wait, there’s more! Yes, another “broccolita” in our garden. Turkish rocket also forms a broccoli (kind of like broccoli raab) with a pungent mustardy tinge. It is best cooked, giving it a nutty flavor. Over the last few years I’ve come to really appreciate the power of this plant. The crown has a deep taproot, which helps support it through drought. This root “mines” the subsoil for important, life-enhancing minerals. The mature hairy leaves protect it from most pests. It is a long-lived perennial, thus it provides increased food mass as it ages. More recently I’ve learned that the nutritional value of Turkish rocket is very high, and its crude protein content (22%) at flower bud stage is comparable to peanuts!

Both of these “broccolitas” are from wild lineages. What does that mean? From our experience, once established these plants are fairly pest and disease resistant (North American pests haven’t figured out how to get through the thick waxy leaves on the sea kale for example), and they seem well adapted to drought. A down side would be that they really haven’t been domesticated at all. So they do need some breeding work to produce bigger broccolis. But, because they are fairly low maintenance, it would behoove many more willing gardeners to tuck them into your perennial beds, and gain a little more fresh spring eating. Enjoy the broccolitas!

The sweet anise roots and foliage of sweet cicely.

An unlikely favorite of ours are the large seeds of sweet cicily (Myrrhis odorata). When still green and unripe they taste exactly like black jellybeans. We all eat lots of them in spring, and they are real favorite among children who visit the garden. Jonathan and I had tried to start sweet cicily from seed when we lived at Wonder Bread farm, but had never gotten it to germinate from the seed packet. We finally bought some plants, and when they seeded for the first time here in Holyoke we threw fresh seed all over the garden hoping that if you might germinate. I’m pretty sure every single one did, creating a new weed problem for us. Now we deadhead what we don’t eat to help keep the species under control. A few years ago we learned a trick that made pulling sweet cicily much more delightful. It turns out that the roots (sometimes as large as carrots) are also anise flavored. They are a bit strong but wonderful when mixed with other root crops and a pleasant nibble fresh out of the ground.

Sylvetta, the perennial arugula.

At this time Jonathan and I were both still single and we spent an inordinate amount of time in winter (and even summer after dark) reading up on useful plants. Many’s the time one of us would cry “dude!” and run over to learn the details of some strange crop on the Plants for a Future database or from a moldy old tome. I had profiled a perennial arugula called sylvetta (Diplotaxis muralis) in Perennial Vegetables. I had filed it away in my head as only hardy to zone seven and written it off as a candidate for our garden. But Jonathan insisted he wanted to try it, and I went along primly thinking to myself that it didn’t stand a chance. Much to my surprise, the plants resprouted vigorously the next spring. The woody parts of this shrub are not hardy, but the roots survived just fine, and these are the only part you eat anyway. So much for my award–winning expertise. Sylvetta has gone on to self-sow with abandon in our garden. We have recently corralled it under our grapes where it can do its thing without smothering anything more delicate. The strong arugula flavor of sylvetta is outstanding in omelettes but perhaps it is best chewed fresh in the garden with a few ripe alpine strawberries.

Groundcover of garlic chives.

The perennial vegetable with the longest season in our garden is garlic chives (Allium tuberosum). This humble plant is viewed by most people in the U.S. as a minor crop at best, or even exclusively as an ornamental. But in China the blanched shoots and flower stalks are a commonplace crop. For Jonathan and I, the garlicky greens are wonderful in spring and fall, though we have many other perennial vegetables to choose from at that time. In late summer this crop comes into its own with twelve inch stalks tipped by an edible flower bud. They can be thrown into whatever you might be cooking for lunch or dinner. I often see bunches of these flower stalks for sale at Asian markets bit I rarely meet a gardener who uses their garlic chives in this fashion. Once they open the flowers are also very lovely and quite attractive to honeybees. This is another case like sweet cicily where we could not get it to grow from seed packets but fresh sown seed is a weedy disaster. We have now isolated our garlic chives in some areas that it can dominate (and be deadheaded), and have ruthlessly weeded it out of our other beds.