Vegetable gardens are a thing of beauty. They please the eye, and they also supply your family with flavorful, healthy vegetables all season long. However, if you’ve been vegetable gardening for awhile or have a large garden, you may wonder if there are other useful plants to add, besides those normal powerhouses like heirloom tomatoes, bush beans, and zucchini so bountiful that come July you’re normally hauling baskets to the doors of any neighbor not as lucky as you. There are, of course, ornamental plants that can be added for decoration, and there are also other plants used for more utilitarian purposes you might not have considered until now.
As you may know, attracting pollinators to your garden is important if you grow insect-pollinated veggies. For most gardeners, honeybees (Apis mellifera) are the most desirable pollinators. For a full rundown of what to plant and what features to add to your garden to attract bees, read How to Attract Bees and Other Pollinators to Your Garden, which appeared in the September/October 2014 issue of Grit.
The article stresses the avoidance or minimal use of pesticides, especially neonicotinoids. Neonics include imidacloprid, the most widely used insecticide in the world. Many home garden pesticides contain this chemical, a derivative of nicotine. The chemical has been implicated in Colony Collapse Disorder (CCD) and may be at least partially responsible for declining bee populations. If you buy your bee attractors as transplants, be aware of how they were treated before you purchase them. Some big-box stores heavily treat their plants with pesticides, even those explicitly sold as a way to attract bees.
Bees are not the only insects that pollinate crops. Butterflies (order Lepidoptera, which also includes moths) do, too, although most move less pollen between plants than bees. Butterflies are also colorful and pleasant to observe, so many gardeners wish to attract them.
Butterflies are attracted to purple, red, orange and yellow flowers, especially if there is a place where they can perch while feeding. Many plants pollinated by perching insects have a modified petal, or labellum (lip), on the flower, on which the insects sit. In addition, butterflies are attracted to plants with short flower tubes, as their mouth parts are not able to reach into longer flowers. A wide variety of flowers attract butterflies, including daisies, asters, coreopsis, zinnias and sunflowers (all in the family Asteraceae).
In addition to the appropriate flowers, butterflies will benefit by access to a water source and native plants on which to lay their eggs and feed their caterpillars. The website for the Lady Bird Johnson Wildflower Center, run by the University of Texas in Austin, has an extensive list of native plants (not just wildflowers) for every region in the United States.
If you live in town, the easiest way to grow native plants is simply to let a patch of ground near your garden grow wild and untended for a few years. If you are worried that this may be unsightly (or perhaps against city ordinances), you can border the area with railroad ties or a low fence.
You could also toss some wildflower seeds around the periphery to make the patch look more like landscaping with native plants as opposed to just a jumble of weeds. You can also specifically seed the area with appropriate natives. Of course, for people who live out in the country, native plants will be prevalent in any area not farmed or landscaped.
If you are planting milkweed specifically to attract monarch butterflies (Danaus plexippus), be aware that the milkweed sold by most nurseries is not among the species of native North American milkweed on which the monarchs rely. Plant a local milkweed species, which will flower at the correct time for the annual monarch migration, if you wish to help out the monarchs. Their numbers are declining, and this once abundant butterfly may soon end up on the endangered list.
The website Monarch Watch has an extensive list of native milkweeds for every state.
In addition to being a pollinator, hummingbirds (family Trochilidae) are a great addition to any garden, and their aerial displays are fun to watch. Males are aggressive and will chase other hummingbirds in spectacular fashion.
Hummingbirds are attracted to long, trumpet-shaped flowers – especially those without a perch. Many of the favorite flowers of hummingbirds are red or pink and hang downwards. Examples include Columbine (Aquilegia spp.), trumpet vine (Campsis spp.), impatiens (Impatiens spp.), morning glory (several genera in the family Convolvulaceae), and petunias (Petunia spp.). The bird will hover in front of the flower and use its elongated beak to reach the nectar. Additionally, hummingbirds have a long, forked tongue that allows them to reach even farther into a flower.
Other features that will attract hummingbirds are nectar feeders, trees near the flowers and feeders, and a water bath. Nectar feeders can supplement the nectar from your flowers to help the birds through periods of decrease in the number of blooms. If you have multiple hummingbirds in your garden, you may want to hang multiple feeders, as males will guard “their” feeder against other birds. Red feeders attract more hummingbirds, which is why most commercial feeders are red. A nearby tree will allow the birds to perch in between feeding runs. Finally, a water bath gives the birds a place to drink and groom.
Like butterflies, hummingbirds will benefit from access to native plant species. Although they are known for feeding on nectar, hummingbirds also eat small insects. A stand of native plants will attract insects, most of which will not be garden pests, for the birds to feed on. Native plants will also attract insect predators. The predators will arrive to prey on local insects living on native plants, and will also hunt in your garden. If you don’t have a lot of native plants near your garden, adding some will create a one-stop destination for hummingbirds. And once you’ve initially attracted some, the birds will return every year.
If you have cats, be sure to hang feeders and place the water bath somewhere inaccessible to them. Domestic cats hunt bird species, including hummingbirds.
If you want to attract a variety of pollinators – including honeybees, butterflies and hummingbirds – plant a variety of flower types. Ideally, you want a blend of flowers so something is always in bloom. This can be difficult to plan, but the more diverse your assortment of flowers, and the more natives you include, the more likely you are to have something in bloom at all times. Native plants also frequently supply more nectar than cultivated varieties. Deadheading fading blooms will encourage the plants to keep producing new flowers.
A healthy garden will attract pests as well as pollinators. Employing crop rotation, hand picking insect pests from plants during cool mornings, and judiciously applying pesticides for larger outbreaks can go a long way toward keeping the pest insects in check.
I would, in fact, argue that you should not seek to completely eliminate pests, as they are prey for garden predators. A garden with a healthy predator-to-prey ratio usually sustains minimal and manageable levels of crop damage and allows you to apply pesticides for only the largest booms in pest populations.
Another trick to minimize the destruction of garden vegetables is to lure pests away from your most prized veggies.
If you grow tomatoes (Solanum lycopersicum), you know how destructive hornworms can be. Tomato plants harboring either tobacco hornworms (Manduca sexta) or tomato hornworms (Manduca quinquemaculata) can have their branches skeletonized overnight by these voracious caterpillars. If you grow a lot of tomatoes, planting some tobacco (Nicotiana spp.) around the periphery will lure some of the tobacco hornworms away and save some tomato plants from total destruction. Both species will lay eggs on both plants, so it isn’t an all or nothing thing.
Tobacco is actually an attractive plant with flowers that attract hummingbirds. In addition, you can plant marigolds (Tagetes spp.) and other related flowers near your tomatoes, as these reputedly ward off tomato hornworms.
Incidentally, you can tell tobacco and tomato hornworms apart by examining their stripes and “horn.” Tobacco hornworms have seven diagonal stripes and a curving red “horn.” Tomato hornworms have V-shaped stripes (often eight) and a straight black or dark blue “horn.”
Another common tomato pest is the Colorado potato beetle (Leptinotarsa decemlineata). This pest affects tomatoes, eggplants (Solanum melongena) and, as the name implies, potatoes (Solanum tuberosum). All of these plants are in the family Solanaceae. (So is tobacco, incidentally.) If you grow a lot of tomatoes, planting a hill of potatoes near the end of your rows could lure some pests away. However, growing tomatoes next to potatoes increases the potato’s odds of contracting potato blight from the fungus Phytophthora infestans. Potato blight is rare, however, when compared to the abundance of Colorado potato beetles.
Squash bugs (family Coreidae) infest most cucurbits, but they are most fond of squash (family Cucurbitaceae) and pumpkins (Cucurbita pepo and two other species in this genus). If you are growing other cucurbits – cucumbers (Cucumis sativus), melons (Cucumis sp. and others), watermelons (Citrullus lanatus), or zucchini (Cucurbita pepo) – planting squash at the end of your rows may lure some of these bugs away.
In order for trap planting to work, you need to monitor the lure plants for insects and destroy the pests. Insects reproduce quickly, so if you don’t take care of the initial infestation, it can quickly spread to the rest of your garden.
Some pests are specific to certain crops. If you’re plagued by corn earworms (Helicoverpa zea), there’s nothing you can plant to lure them away. Conversely, some insect pests are generalists, and there isn’t a single preferred species to be used as a lure. If your garden includes a lot of a single type of vegetable, a general approach would be to plant other vegetables in the same botanical family at the end of your rows, or plant flowers from the same family as ornamentals to attract pest predators.
Grouping plants into blocks of the same family can also help you if you practice crop rotation. For more on crop rotation, read Small-Scale Crop Rotation: Inspired Vegetable Gardening from the January/February 2013 issue. Grouping plants is another tool – along with crop rotation, hand picking large insect pests, and pesticides – to keep their numbers in check, though it will not completely do away with insect pests.
Vineyards can be a beautiful sight, with rows of grapevines (Vitis vinifera for the most well-known types of wine) extending up a hillside. If you’ve ever visited a vineyard, you may have seen rose bushes (Rosa spp.) planted at the end of the rows. Although roses are lovely, they are there for a more practical reason. Roses are susceptible to two of the fungal diseases that also plague grapevines – powdery mildew (Erysiphe necator) and downy mildew (Plasmopara viticola). Vineyard managers monitor the health of the rose bushes. If they see mildew in any of the roses, they can examine the nearby rows of grapevines for disease and take action, if needed.
A similar system can work if you plant a lot of squash. Cucumbers (Cucumis sativus) are especially sensitive to the type of downy mildew (Pseudoperonospora cubensis) that affects other cucurbits, including melons, pumpkins and squash. If mildew is a problem in your area, installing a cucumber trellis to border the northern edge of your squash patch (where it won’t shade the squash) can give you an early warning system for this fungus.
If you plant one species of plant to serve as an early warning for fungi (or bacteria or viruses), you will need to monitor it and take care of the problem when it arises. If you let the “sentinel plant” get too diseased, it will serve as a reservoir for the pathogen to infect your vegetables. Either spray the plant with the appropriate remedy (in the case of fungi), or pull the plant and dispose of it away from your garden (in the case of viral or bacterial disease). Do not compost diseased plant waste if that compost will be used in your garden.
If you move and are establishing a new garden, you may not know what the previous landowner grew or what pests are common in your new area. Many modern vegetable cultivars have been bred to include resistance to the diseases that most commonly plague them. Planting resistant vegetable varieties is a smart move when starting out.
However, you may want to plant one non-resistant plant in each block of veggies just to see what is lurking in your garden. If a problem arises, pull the plant immediately and you’ll know to only plant resistant cultivars in the future. However, if the sentinel plant thrives, you’ll know that you can plant non-resistant cultivars – for example, heirloom varieties – next time around.
A vegetable garden can benefit from nearby native plants, flowers planted to attract pollinators, and a diversity of vegetable crops – perhaps some designed to lure certain pests away from other vegetables. Such a garden will likely be healthier and suffer less from pests and diseases than a garden containing only a few vegetables surrounded by a lawn. And, the presence of butterflies and hummingbirds adds to a garden’s visual appeal. I enjoy sipping a cold beverage outside by my garden when the day is done, so the visual appeal is important to me.
Chris Colby is an avid gardener who lives in Bastrop, Texas, with his wife and their cats. His academic background is in biology – a Ph.D. from Boston University – but his main interest is in brewing beer.