Archives For Lisa Hilgenberg

Grafting Tomatoes

To graft or not: that is the question.

Lisa Hilgenberg —  May 25, 2014 — Leave a comment

Grafted tomato plants are available at garden centers and through mail order nursery catalogs, but sell out quickly, as the idea has captured the interest of home gardeners, farmers, and professional greenhouse growers.

PHOTO: Tomato graft with silicon tubing holding the graft in place to heal.

The finished tomato graft: this will be placed into a “healing chamber” for a week while the graft seals.

An ancient art and science long used on fruit trees, grafting is the placement of the tissues of one plant (called a scion) onto another plant (called a stock). The rootstock is thought to impart disease resistance and increased vigor to a less vigorous—perhaps heirloom—tomato grafted on the top, producing more tomatoes over a longer period of time.

Curious about the process and whether the price tag could be justified—grafted plants run from $9 to $18 a plant—I decided to graft some tomato plants myself and grow them out. My first foray was in winter 2013. The Chicago Botanic Garden’s propagator in the plant production department, Cathy Thomas, had just returned from a conference at Longwood Gardens, where one of the topics was grafting vegetables. She willingly supported my quest and enthusiastically discussed the details with me.

The process seemed fairly straightforward after we settled on which varieties to graft together. Deciding to graft the cultivar ‘Black Cherry’ onto ‘Better Boy’ rootstock, we worked with tiny, 3-inch-tall tomato starts, taking care that the top and bottom stems of each plant were exactly the same diameter at the place they were to be grafted. Our grafting tools included clear silicon tubing cut to 10 to 15 millimeter lengths, a new, unused razor blade, and our tomato seedlings.

Starting by sanitizing our hands, we used a new razor blade to slice the stem of the scion (top graft plant) off at a 45-degree angle. The plastic tubing, soon to be the grafting clip that would bandage the graft union, was prepared by splitting it in half. All the leaves were removed from the scion, leaving only the meristem. (The meristem is the region of stem directly above the roots of the seedling, where actively dividing cells rapidly form new tissue.) Two diagonal cuts were made, forming a nice wedge to fit into the rootstock. The rootstock was split and held open to accommodate the scion. A silicon clip was slipped around the cleft graft. Newly grafted plants were then set into a “healing chamber,” a place with indirect light and high humidity, for up to a week. In the healing chamber, the plants can heal without needing to reach for light, which can cause the tops to pop off. We placed our new grafts in a large plastic bag in the Regenstein Fruit & Vegetable Garden greenhouse. The healing began.

PHOTO: Slicing the top off the rootstock tomato seedling.

Cut the root stock off at the meristem; discard the top of the seedling to avoid confusing it with the scions you will be grafting.

PHOTO: Slicing the top of the meristem to insert the scion graft.

After cutting off the top of the rootstock, user the razor to vertically slice the top part of the remaining meristem.

PHOTO: Removing the leaves from the tomato scion graft.

Remove the extra leaves from the scion, leaving only the top set.

PHOTO: Sharpening the tip of the scion to a point.

Make two 45-degree cuts to the end of the scion to create a sharp tip to insert into the rootstock.

PHOTO: The scion is inserted into the rootstock of the tomato graft.

Using the razor’s edge to pry open the split rootstock, gently insert the prepared scion.

PHOTO: Closeup of the finished tomato graft.

Slice the silicone tubing open and wrap the cuff around the graft, entirely covering the graft to support the top plant and speed healing.

Two weeks later, we had a dismal one-third survival rate! Much to my relief, the lone survivor was a superlative tomato plant in almost every way. Oh, what a strong tomato we had! My excitement rose—what if heirloom tomatoes could be as delicious and more prolific and adaptable? When soils warmed, we planted our grafted tomato out in the Fruit & Vegetable Garden, positioned right next to a ‘Black Cherry’ plant growing on its own root, so the differences would be easy to discern. Our hope was that we could address some of the ins and outs of grafting for the public, and the feasibility of DIY (Do It Yourself) for gardeners. Do grafted heirloom tomatoes have more vigor, better quality, and bear more fruit than ungrafted “own-root” heirloom tomatoes? Which has a more abundant harvest over a longer period of time?

Last summer, our grafted tomato plant certainly provided the earliest harvest. Comparatively, it was earlier to fruit than the plant grown on its own root by two weeks, and was prolific throughout the season. That being said, in the organic system of the Fruit & Vegetable Garden, our soils are nutrient-rich and disease-free in large part due to crop rotation and soil-building practices. The question used in marketing “Is the key place for grafted tomatoes in a soil that has disease problems?” didn’t apply to us. Are grafted tomatoes the answer for those with less-than-ideal environmental growing conditions? For greenhouse growers unable to practice crop rotation as a hedge against a build-up of soil-borne disease, or home gardeners who contend with cool nights and a short growing season, I would say yes, I think so, but at a cost.

PHOTO: Grafted tomato in healing chamber.

Place the finished graft in a humid location, out of direct sunlight, to heal for up to one week.

When planning on grafting, growers must buy double the amount of seed and need to double the number of plantings (to account for the graft failure rate) to maintain the same number of viable seedlings to plant. Cathy and I tried our grafting project again this spring and are looking forward to growing ‘Stripes of Yore’ and ‘Primary Colors’ on ‘Big Beef’ hybrid rootstock. I swapped seed for these unusual varieties with a tomato enthusiast who attended our annual Seed Swap this past February. Our rootstock has excellent resistance to common tomato diseases: AS (Alternaria Stem canker), F2 (Fusarium wilt), L (Gray Leaf Spot), N (Nematodes), TMV (Tobacco Mosaic Virus), V (Verticillium Wilt). So far, three of our eight plants are viable, healed, and strong.

We are looking forward to planting the grafted tomatoes the week of June 8 in the Fruit & Vegetable Garden, right alongside some of the other 52 varieties of heirloom and hybrid tomatoes. So whether you choose a regular or a grafted plant at the garden center this weekend, come on over! It’s time to talk tomatoes! @hilgenberg8

©2014 Chicago Botanic Garden and my.chicagobotanic.org

Recent interactions at the neighborhood market have reaffirmed our work of inspiring folks to become more adventurous vegetable gardeners and consumers. The girl at the checkout counter often questions my vegetable selections. Recently, she had to ask (holding up a bag of produce), “…peas?” I said, “fava beans.” Of another bag, she asked, “lettuce?” I replied, “Napa cabbage.”

It’s exciting to expand our food horizons. Like the mouse who expands his horizons in If You Give A Mouse A Cookie by Laura Numeroff, when you set out to do one thing, it often snowballs, becoming a cascade of challenges and rewards. You often become more involved and do more than you originally set out to accomplish. The mouse only wanted to eat a cookie, but quickly realized that if he ate that cookie, he’d need a glass of milk. Set a goal of growing three new vegetables this year—it may be the beginning of an interesting sequence of events. If you grow three new veggies in the garden…you’re probably in for new culinary adventures in the kitchen, or maybe you’ll dig out an old family recipe. Perhaps you’ll share a meal with a neighbor. Sounds pretty good to me. Here are a few veggies you might like to try.

PHOTO: Young kohlrabi plants bordered by onions on the Fruit & Vegetable island.

Kohl is the German word for cabbage, and rübi means turnip. Find kohlrabi (Brassica oleracea ‘Kolibri’) in the Fruit & Vegetable Garden.

Kohlrabi

The Victory Garden movement of World War II was responsible for bringing kohlrabi to the American dinner table, because it was a reliably cooperative vegetable to grow. There are two old varieties of this underrated gem—green and purple. ‘Early Purple Vienna’ is not only a beautiful heirloom in the garden; it has sweet, white flesh, and is crisp like an apple when eaten as raw matchsticks. It can also be cooked like cabbage. A quickly-maturing, hardy spring and fall crop, it matures in 55 days. Due to its ability to hold well in the field, the bulbs (botanically, the edible bulb is actually part of the stem) won’t need to be harvested all at once. You can enjoy one sweet kohlrabi at a time. 

PHOTO: Rutabega in the garden.

Rutabaga (Brassica napus)

Rutabaga

Another common vegetable in the Victory Garden, rutabagas are “a butter and cream veggie, as Scandinavians would prepare them,” according to Deborah Madison in Vegetable Literacy. Rutabagas are named for their dense roots—the name in Swedish means root bag. They are also commonly known as Swedes or yellow turnips. This cabbage turnip cross yields lovely, pale, crisp, buttery yellow flesh. More nutritious than turnips—unless you eat their greens—rutabagas are delicious mashed or pureed with root vegetables or julienned into french fries. Long-seasoned in the field, they take 90 days to mature and last a long time in proper post-harvest storage. What a difference the rutabaga made to hungry families in lean times! 

Turnip

Our final selection, turnips, are best grown quickly during the cool seasons of spring and fall, and vary greatly in taste and quality depending on climate, variety, and culture. Some varieties were widely used to feed livestock, while other turnips indulged the most sophisticated epicure. The Hakurei turnip is a beautiful, white, Japanese salad turnip that is best grown quickly (40 days) in the spring garden. When harvested young, Purple Top Globe lends itself to delicious sea-salted slices. While turnips and radishes resemble each other, turnip greens are more nutritious. Both can be sweet and crisp or hot and spicy depending on maturity and weather. Enjoy raw or cooked turnips with radish greens. They are wonderful when eaten together.

PHOTO: A bunch of white Hakurei turnips.

Hakurei turnip ( Brassica rapa ‘Hakurei’)

Turnips also happen to be part of what we are growing this year as part of our Victory Garden display, growing the vegetable varieties and plants people would have grown during wartime to sustain themselves and their community. The value of Victory Gardens is tremendous, and the message is current again: a local and multi-faceted food system—home gardeners, urban farmers, other small scale growers—supports a more resilient community overall.

As these Victory Garden plantings unfold in the Fruit & Vegetable Garden this season, perhaps we will take a moment to contemplate our own personal food histories allowing them to inform us as to why we eat the way we do. Our work of today finds such congruence with the Victory Garden experience—a time when the United States government printed and circulated vegetable-growing primers. This was a time when our country grew 41 percent of its produce at home out of duty, honor, and necessity, and with the help provided by botanic gardens, community gardens, horticultural societies, and garden clubs. While our war is thankfully different today, it is a war still. It’s a war on nutritional deficiencies and obesity, on food deserts and hunger. Learning to grow your own is a powerful way to participate, to contribute and to change your food footprint!

Like the mouse who eats the cookie, which leads him to ask for a glass of milk, perhaps we will plant the heirloom seed that will grow a bumper tomato crop that will necessitate learning how to can tomato sauce. Whether it’s food preservation, saving on your grocery bill,  sharing with a neighbor, or exploring exotic vegetables that interests you, dig deep and find the motivation to grow food at home!

Tweet to me @hilgenberg8 and let me know which three vegetables you chose to plant in your garden this spring. Good growing to you!


©2014 Chicago Botanic Garden and my.chicagobotanic.org

Historically, fruit trees, shrubs, and berries were grown at home out of necessity. Colonialists were entirely dependent on what they could produce themselves, and in time, a fruitful garden became a common symbol of independence from foreign imports—highlighting a new American pride in agriculture.

The farm-to-table movement of today epitomizes the fruit-growing traditions of the past by “growing as close to the plate as possible.” Sweet, juicy fruit can be easily grown in gardens of all sizes: on small urban lots, in containers on terraces, or in large suburban gardens. Harvesting homegrown fruit continues to be a gardener’s most satisfying pleasure, and with a bit of advance planning, choosing suitable varieties to plant this spring is possible. Here are a few ideas to get you started creating, and/or caring for, your edible landscape.

PHOTO: A hanging basket growing a mix of strawberry cultivars and lettuces.

Day neutral strawberries are grown in our vertical wall and hanging baskets in the Regenstein Fruit &  Vegetable Garden.

Plan to plant strawberries

No grocery store strawberry ever tastes as good as one grown in your own yard. An easy starter crop, strawberries are self-fertile, so you can start small if you like—plant just one variety or only one plant—and still reap a reward. Choose strawberry varieties carefully, however—they vary greatly in flavor, disease-resistance, tolerance of different climates, and harvest time.

Good choices for Illinois gardens are larger June-bearing strawberries such as ‘Earliglow’ and ‘Allstar’. Day-neutral or everbearing strawberries were developed to produce flowers and fruit continuously throughout summer and fall, ignoring the seasonal effects of day length on fruit production. Of the many day-neutral and everbearing varieties to choose from, ‘Tristar’ is a reliable berry for our zone. At the Garden, we grow everbearing strawberries ‘Mara de Bois’ and ‘Seascape’ in hanging baskets and vertical plantings, because they are among the first to fruit in the spring, but also produce a June crop followed by a final fall crop.

Planting several varieties together in your garden extends your harvest time, ensuring there are plenty of strawberries for eating out of hand and enough fresh berries left over to make strawberry jam.  

Choose healthy plants for a healthy harvest

Start with quality, virus-free, and disease-resistant plants. Mail order nurseries and garden centers have bundles of bare-root plants available. Lesser quality plants are prone to fruit rot, mold, and fungal diseases like Verticillium wilt.

PHOTO: Glass cloche cover strawberry plants in a garden plot in early spring.

Strawberry flowers are susceptible to frost. Here, a transparent plant cover called a cloche (from the French word for bell) is used to protect plants if frost is expected.

Select a planting location in full sun; avoid low-lying spots or crop beds that have grown tomatoes, potatoes, or cane fruit in prior years. These crops can harbor soil pathogens like Verticillium and Phytophthora which can affect new plantings. While strawberries prefer to grow in soil with a bit of acidity, a pH of 6.2 is ideal; the varieties mentioned above perform well in Chicago.

Aim for early spring planting, as soon as the soil can be worked, and its temperature is above 40 degrees Fahrenheit. Mid-April to mid-May is ideal. Space plants 12 inches apart, leaving 3 feet between rows. Fifty plants produce enough fresh home-grown fruit for four people all summer long.

Plant with midpoint of crown at soil level. Roots should be planted straight down. Strawberries are shallow-rooted, and mother plants spread by runners—which can be removed if desired, to develop stronger plants and to promote bigger fruit.

Water your plants well, particularly when they are fruiting. Mulching with straw helps keep fruit clean and dry, and up off the soil.

Spring tasks: Prune Raspberries

Red, yellow, black, or purple raspberries are easy to grow in hedgerows as natural barriers along lot lines or on post-and-wire trellises. Cane fruit is best managed with proper spring pruning, which prevents a tangled mess and makes your late-summer harvest far easier. Regular pruning keeps brambles in line while allowing air flow through the plant—lessening the risk of fungal diseases like Botrytis and rust, and increasing both yield and berry quality. Both types of raspberries—summer-bearing and everbearing (or fall raspberry)—benefit from a good March pruning.

PHOTO: Different kinds of berries in baskets, lined up in a grid.

A bountiful berry harvest on its way to our Farmers’ Market? A bountiful home harvest is also possible with vigilant pruning.

Summer-bearing raspberries produce a single crop in the summer on canes which have overwintered. It is important to confine them to a 1- to 2-foot-wide hedgerow to encourage air flow and sunlight. Begin your pruning by removing dead, diseased, or damaged canes first. Then, head back (prune) the spindly top 6 inches of cane tips. Removing the thinnest wood which produces the smallest berries forces the growth into the more vigorous lower part of the plant.  Finally, remove less vigorous canes—in an established plant, those canes with less than a pencil’s diameter thickness—leaving 6 inches between canes (enough room to easily pass your hand between canes).

Fall-bearing red and yellow raspberries can produce fruit on both the current season canes (called primocanes) and second-season growth (floricanes). Thus, they can be pruned to bear one or two crops with a method called, “double cropping.” (We demonstrated both methods last year on our brambles in the Regenstein Fruit &  Vegetable Garden.)

  1. To produce one heavy fall crop, cut all autumn raspberry canes back to ground level in the spring. Canes should be cut as close to the ground as possible to encourage new buds to break just below the surface. All new canes will grow from this radical pruning and produce a single crop of berries.
  2. A second method of pruning produces a small crop on the previous year’s growth and later, a second crop on the current season’s canes. When a double crop is desired, remove dead, diseased, or damaged canes in March, leaving the vigorous canes to fruit. Tip-prune those back by one-third of the total length of the cane, or to trellis height. The new shoots or primacies will produce the second larger crop. After the second fruiting, the canes will die and should be removed.

Pruning for blackberries is similar to raspberries. They are also pruned in March by heading back the “leaders”—the main canes—by one-third (or about 36 inches). This tip-pruning helps to stimulate the growth of lateral branches, which is where blackberry sets fruit. The lateral branches should be pruned back to 12 inches, or where the branches’ thickness is about the diameter of a pencil. 

Want to learn more about cultivating berries? Join us for Growing Fruit Trees and Berries, May 29 to July 10, or check out other fruit cultivation classes at the Garden this spring.

©2014 Chicago Botanic Garden and my.chicagobotanic.org

Orbs of October

Fall color theory

Lisa Hilgenberg —  October 16, 2013 — Leave a comment

Color theory states that orange radiates warmth and happiness by combining the energy and stimulation of red with the cheerfulness of yellow. This is a fit description for the harbingers of autumn’s harvest, the seasonally evocative winter squash and pumpkins.

Did I mention that the “Great Pumpkins” have arrived in the Regenstein Fruit & Vegetable Garden?

PHOTO: Atlantic Giant pumpkins.

Unbelievable, yet real: Atlantic Giant pumpkins (Cucurbita maxima ‘Atlantic Giant’) adorn beds of parsley, chard, and heirloom root vegetables.

So visually compelling is the color-saturated rind of the world’s largest fruit, and so heavy. All of this certainly explains what your fruit and vegetable team has witnessed in the Garden. There is pure joy as our visitors first glimpse the great pumpkins—ooohs and ahhhhs and squeals of delight, as folks of all ages decide how best to connect with the fruit: Is it real? Should I touch it? Should I sit on it? Hug it? Photograph it? People even talk to our anthropomorphic fruit. 

But the giant pumpkins are just one part of the diverse Cucurbita garden art growing in the Fruit & Vegetable Garden this season. While they seem to be called “squash,” “pumpkin,” and “gourd” interchangeably, there is actually a science to identifying these cultivars, and pretty much everything called “pumpkin” is really a squash—although “pumpkin” is most commonly used to describe those distinctive orange orbs.

Cucurbita maxima are squash with softer rinds and flesh, growing on long vines with large, hairy leaves. Harder-skinned “winter squash” are typically Cucurbita moschata, including butternuts and acorn squash. They also have trailing vines and hairy leaves, but tougher flesh and rinds, and a ridged but still soft stem. Only Cucurbita pepo are considered true pumpkins, with tougher flesh and rinds, leaves that are downright prickly (not just hairy), and a woody five-sided stem.

PHOTO: Warted hubbard squash.

Warted hubbard squash (Cucurbita maxima ‘Chicago’s Warted’) is delicious now, and delicious later.

Cucurbita maxima ‘Chicago’s Warted’ is an heirloom developed by Budlong Gardens of Chicago. It was introduced by Vaughan’s Seed Store of Chicago in 1894. The 13-pound fruit are dusky olive green, and deeply wrinkled and warted with a classic hubbard squash teardrop shape. These gems have a fine-grained, sweet orange flesh. We planted ours way back at the end of May—perfect timing for this 110-day crop. The hubbards are versatile winter squash that can be eaten right after harvest, or stored until the flesh sweetens around the new year.

PHOTO: Australian blue squash.

Australian blue squash (Cucurbita maxima ‘Queensland Blue’ ) can be stored for an incredibly long time.

A member of the avant-garde Australian blue group of squash, Cucurbita maxima ‘Queensland Blue’ is not often seen growing in the field. While they hail from South America, the blue squash varietals grow equally as well in Australia (for which they are named) because of similar temperatures and length of growing season. We found the seed at Seed Saver’s Exchange in Iowa. This is a bottle-green keeper that, if properly harvested and well-cured with a 4-inch “handle,” will store for more than a year—maybe two. It is a fantastic eating-quality squash with smooth, rich, brilliant orange flesh.

PHOTO: Waltham butternut squash.

Waltham butternut squash (Cucurbita moschata ‘Waltham’) looks like a buff-colored peanut.

Cucurbita moschata ‘Waltham’ looks like a blocky, buff-colored peanut. We planted it in the warm soil of mid-June, which squash of this species prefer. Waltham butternut is a uniform producer that must be harvested before the slightest touch of frost.

PHOTO: Growers and staff positioning a mammoth pumpkin on a forklift.

Moving this Atlantic Giant to its current location took a full day of careful handling…and more than one forklift.

Make sure you have a forklift available before you think of growing Cucurbita maxima ‘Atlantic Giant’, which can easily grow in excess of 1,000 pounds. This squash that looks like a pumpkin surprisingly does not need much more room than the average pumpkin patch to grow, but organic compost can help boost its final size.

PHOTO: Winter Luxury pumpkin.

The champion of pie pumpkins: Cucurbita pepo ‘Winter Luxury’

Cucurbita pepo ‘Winter Luxury’ is diminutive in stature but mighty in taste. The fine, rough netting around the shell is a distinguishing feature of this 1896 heirloom. This is the gold-standard pie pumpkin that can be eaten right out of the garden. It won’t store as long as the other species.

PHOTO: Jarrahdale Australian blue pumpkin.

Stunning when sliced: Jarrahdale Australian Blue (Cucurbita maxima ‘Jarrahdale’)

Cucurbita maxima ‘Jarrahdale’—our second unusual Australian blue—is a deeply-grooved, slate-gray squash with dense, sweet, deep orange flesh and a thin skin.

PHOTO: Pink Porcelain Doll pumpkin.

Purchase Porcelain Doll (Cucurbita moschata ‘Porcelain Doll’) seed from Pink Pumpkin Patch Foundation.

Cucurbita moschata ‘Porcelain Doll’ is a pink cheese pumpkin that has become the symbol of breast cancer awareness among pumpkin growers across America. Growing this decorative hybrid will ensure a donation to research is made.

PHOTO: Small Mixed gourds.

Grown for display, these Cucurbita pepo ‘Small Mixed’ gourds are generally better food for squirrels and raccoons.

There are three basic types of gourds in the Cucurbitaceae, or squash family: Cucurbita (ornamental squash), Lagenaria (utilitarian gourds used for things like containers or birdhouses) and Luffa (vegetable sponge). These Cucurbita pepo ‘Small Mixed’ ornamental gourds are just pumpkin varieties with poor flesh quality—either too fibrous or too watery for eating—but with beautiful color and texture for use in fall arrangements. We grew these up on a trellis. They store better in a cool environment but can easily last indoors for seasonal holiday decorating.


Choosing a pumpkin this weekend?
Use these tips and know what you’re selecting when you shop:

PumpkinHandle pumpkins carefully, by using two hands to lift them. Although it is tempting to pick pumpkins up by the “handle,” a pumpkin’s decomposition accelerates once the stem has broken off.

Well-grown pumpkins should be heavy for their size, with telltale ripeness indicators like deep, saturated color, and brown stems. The rind should be hard—impenetrable when lightly pressed by a fingernail—and have a glaucous, dull sheen.

Once you get your pumpkin home, wash the rind with a mild bleach solution to remove bacteria and extend the life of the pumpkin.


I just cannot resist asking: Orange you glad you visited the Regenstein Fruit & Vegetable Garden? Learn more about pumpkins in Plant Information and The Smart Gardener.


©2013 Chicago Botanic Garden and my.chicagobotanic.org

It’s the season for grilling—time to share a simple, herb-related trick with the grill master at your house.

PHOTO: rosemary sprigs tied to a wooden spoon make an herb brush

Wooden spoon + rosemary + garden twine = herb brush

Fashion an herb brush out of a wooden spoon, a bit of kitchen twine, and freshly-snipped twigs of rosemary. Use the aromatic brush to flavor roasting meats like lamb, chicken, or pork—just dip it into marinade or olive oil and apply liberally.

Another rosemary trick: Try threading chunks of meat onto rosemary skewers for a delicious infused kabob. Genius!

PHOTO: homemade sage grill brush.

A beautiful plant in the garden, sage is most familiar as the flavoring in stuffing—but it makes a great grill brush, too!

A sage brush is perfect for sweeping marinades onto grilled chicken. After the meat is cooked, snip the herb into softened butter to create sage butter to serve along with it at the table.

The genus Salvia comes from the Latin word salvere, “to save or to heal,” hence this herb’s connection to long life and good health. A wonderful wish, indeed!

PHOTO: snipping tarragon for a garnish.

After using your tarragon brush on grilled fish, snip the herbs over vegetables as a garnish.

French tarragon easily becomes a grill brush for basting butter or marinades onto grilled fish. Just before serving, snip the “brush bristles” atop steamed new potatoes for a flavorful finishing garnish.

Join us for more tips, plus fun, facts, and fragrance at the Garden’s Herb Garden Weekend, July 27-28!


©2013 Chicago Botanic Garden and my.chicagobotanic.org