Sure, insects cause flower growers some noticeable heartaches, but they can be controlled organically—with beneficials, diversity, selecting the right flowers for your region, and even with guinea hens.

First the bad news: There are about a million different kinds of insects. Some articles, experts and insect books could readily push you right over the edge from fresh to (gasp) silk flowers. Ah, but the good news is flowers, most kinds you want to grow for market anyway, are relatively pest-free. “Relatively” means problems do crop up. Some flowers are better avoided in some parts of the country, and, of course, there are good years and there are bad years for certain pests. But don’t worry, you can usualy deal with them sustainably.

That said, everyone has had their heart broken. My fall silky Asclepias (Asclepias curassavica) — two nice, long rows that I had babied from seed and planted out at the beginning of July for a great show at market on those balmy, autumn Sundays in Emmaus, PA — were my heartbreak. With the usual craziness of fall produce and flower sales and readying the high tunnels for winter, the Asclepias didn’t get checked close enough or often enough. Pretty soon, a gooey yellow scarf enveloped every stem so thickly they were a total loss. Aphids. Thousands of aphids. So we gingerly pulled all the plants — and started more dried arrangements to make up for the loss. Aside from aphids in the high tunnel on one small row of sunflowers near the door (others in the same high tunnel center were untouched and I was able to wash the aphids off, dunking them in a bucket of water), we have had no major insect problems on flowers. Ever. We had a few Japanese beetles, a few cucumber beetles and a few inch worms that entertain from the Ageratum. That’s it.
Diversity and good soil make a difference.

Lynn Byczynski, grower and author of The Flower Farmer (www.growingformarket.com), says grasshoppers are her number one problem in Kansas. “We’ve found them to be unperturbed by anything we have unleashed on them, including Nosema locustae and Beauveria bassiana.” That’s Latin for beneficials/biological controls which are labeled for grasshoppers and are organically acceptable. “Grasshoppers are highly attracted to certain species of plants including dahlias, mums and marigolds, so we don’t even try to grow those anymore.”

Then, like all growers, Byczynski adds, “This year, we will try guineas on the advice of many Growing for Market readers. But we won’t know for a while whether our super-hoppers will be controlled by these voracious birds.” We inherited a few pretty tame guineas at Pheasant Hill Farm last year and they love working within eyesight of us. We’re hoping they get all the ticks, Japanese beetles and other insects that might bother our flowers. We intend to train them with white millet this spring to go where the bugs might go. (For more information on guineas, see Jeannette S. Ferguson’s book Gardening With Guineas or visit her website at www.guineafowl.com where you can even hear them.) Guineas also eat a lot of weed seed. Down side can be noise and their traveling habit, but, supposedly, can be trained. We’ll see.

Besides grasshoppers, other insects, Byczynski says, are really only a minor inconvenience on her cut flower crops. “Part of that is because we have an ‘organic attitude’ about fitting our farming into the ecosystem. For example, we grow dill, fennel and Asclepias for bouquets. But we are happy to defer to the monarch and swallowtail butterflies when their need for food arises. We just leave these plants in the garden, let them get munched down by the caterpillars and then enjoy the spectacle of metamorphosis.”

Steve Bogash, regional commercial horticulture educator in Central Pennsylvania, says flowers generally ARE pretty easy and low on insect problems. “The way you grow out flowers as a small grower is so different from large monoculture, you see different problems,” adds Bogash, Franklin County Cooperative Extension agent and former grower. “Small growers with diversified crops will have an incredible mix of insects that will eat each other before there are problems.”

What’s Easiest To Grow with Insects in Mind?

There are lots of good, easy ones, say Dr. Stanton Gill, with Central Maryland Research and Education Center, Maryland Cooperative Extension. He, and Bogash named some of my favorites: Sunflowers, Zinnia, Karma dahlia, Celosia, tall Ageratum, Statice, and Salvia leucantha.

SUNFLOWERS — Succession planted from March and going until frost (longer if you have a high tunnel and extra protection), sunflowers don’t have many insect problems. Gill notes that you may see some adult striped or spotted cucumber beetle damage as the season progresses — they can do damage to the petals. While they don’t destroy the plant, they do destroy their value as a cut flower. The solution: Don’t grow cucumber plants, or other veggies the pests love, in the area. You can use Neem oil, a tropical-tree extract, that kills many pests on contact, he says. (Certified organic growers should check their latest catalog or www.omri.org for current status of organically approved pesticides). At Pheasant Hill Farm, we cut the sunflowers as the first rays open, especially if there seems to be a problem with beetle damage, and keep the sunflowers in the cooler. If you miss a few flowers with a hole or two (not impossibly chewed flowers) give the flowers away to kids at the farmers’ market. They’ll be thrilled. So will Mom.

ZINNIAS — The garden workhorse isn’t usually bothered by insects or pests. We often find those nasty, big spiders making fascinating webs between them here and there. Actually they’re Orb-web spiders, yellow and black argiope, and they are working for you, so work around them. Japanese beetles can sometimes hit zinnias, Gill says.

KARMA DAHLIA – I recommend these highly  Bogash loves them. Gill says in some areas, people have problems with grasshoppers (especially if there are high grasses or fields are nearby), cucumber beetle, and leafhopper.

Others mentioned include Celosia (especially wheat), Ageratum, Statice and Salvia leucantha which have very few insect problems, Gill says. Gill also recommends Liatris, Sedum (Autumn Beauty), Tuberose, Phlox paniculata and Lisianthus as of little interest to insect pests (but bear in mind lissies are hard to start). Trachelium caeruleum, lavender to dark blue flowers borne in panicles at the end of the stem, are also relatively pest free, he says.

What Are the Biggest Problems for Flowers?

Insects that can be a problem for flowers include aphids, thrips, spider mites, leafhoppers, beetles and caterpillars, says Bogash. “They can often be controlled with natural parasites and predators.” While beneficial insects can be bought from biological control companies and through many catalogs, the alluring descriptions can be daunting. Both Gill and Bogash say beneficials work better in a greenhouse setting. In fact, Bogash says in a closed system, beneficials work very well. In tunnels, they can be competitive. “Large predators, lacewings, ladybugs don’t like being around each other. Maintaining sanctuaries, giving them a place to go, helps.” For beneficials, various catalogs and websites tell you how many you will need, when to release and what to expect, including IPM Laboratories, Inc., www.ipmlabs.com. The Association of Natural Bio-control Producers web lists distributors in the U.S. at www.anbp.org.

Another resource for the flower grower fighting insect pests is the sticky trap, yellow or blue cards (available at many nursery centers and through many seed and greenhouse catalogs) with a brightly colored surface coated on both sides with a special sticky, non-drying glue. These traps will catch many insects and can help you with monitoring them. Unfortunately, they’ll also trap beneficial insects. They’re especially useful in the greenhouse environment.

If you have a diverse operation and are good to the soil, insects shouldn’t have a prohibitive impact on your flowers. In other words, you don’t need to be an entomologist to successfully grow and sell specialty cut flowers on a small farm. But some knowledge of the good guys and the bad guys, and keeping a close watch on your flowers, is important. It can be educational and kind of fun, too (as long as the insects you find are not appearing in record numbers).

Lots of catalogs have magnifiers that let you see the tiny insects up close and personal, whether on plants or sticky traps (one is Gempler’s at www.gemplers.com). There are some good books out there with pictures of various stages in the insect’s life cycle, too. Our new favorite is The Ultimate Guide to Backyard Bugs, Garden Insects of North America by Whitney Cranshaw. Penn State College of Agricultural Sciences (as do many ag schools around the country) has a booklet entitled “Managing diseases, pests and plant growth in Greenhouses”. It’s good outside the greenhouse, too, has good insect/disease descriptions (but no pictures) and you can ignore the heavy chemical info.

So, without letting the following get you paranoid (because as we said above, flowers aren’t that difficult when managed well), here are some tips on . . .

The biggest problem insects

APHIDS — Aphids can be winged or wingless. They develop wings as numbers in their colonies increase so they can move on to less populated areas and wreak further havoc on your flowers. They are generally small, according to Penn State’s booklet, 1 to 3 mm, and soft bodied. Caught on yellow sticky cards, their front wings usually have two parallel veins close to the outer edge which ends at a dark, thin part. Their legs and antennae are long. Their color varies and as they get bigger, they shed their exoskeleton which can be found on leaves or stuck in their sticky secretions. Penn State says the insects “feed by inserting their stylet-like mouthparts through plant tissue directly into the phloem and removing plant sap. Feeding can lead to plant stunting and deformities.” When you have a lot of them, they look like a yellow, sticky mess all over your flower stem, leaves, bud. The sticky secretion is called honeydew, which can be a growth base for sooty mold.

That’s not all. Aphids are responsible for transmitting some 60 percent of all plant viruses on ag crops worldwide. Why are they such a problem? Females give birth to live offspring, three to 10 a day, that immediately start to feed. They don’t need to mate, so each female gives birth to MORE females. Within a week, the offspring are ready to reproduce.

“With aphids, if I can be patient, nature often helps,” says Steve Bogash, regional Extension commercial horticulture educator in Central Pennsylvania — if the problem isn’t too severe. “I was all set to get out the spray for an aphid problem at home and didn’t get around to it. Then I saw lots of lady bug larvae — which generally will take care of the problem.”

Byczynski says she occasionally sees some aphids early
in the season — greenhouse ranunculus seem especially susceptible. “They are easily controlled by insecticidal soap,” she says. Insecticidal soap kills by disrupting membranes. Horticultural oils can also be effective, killing by suffocation. Organic growers need to check each product with their certifying agency/OMRI manual, because not all organic pesticides are created equal and while some are allowed, others are restricted.

Critical to aphid control is sanitation. Keep an eye on flowers before problems develop. Start inspecting plants at the lower leaves upward. And get rid of weeds near any problem spots that develop. Biological controls can be very successful, especially in a greenhouse. Lady beetles (Hippodamia convergens) sold as adults can clean up bad problems. They also feed on other soft-bodied insects like thrips. Lacewings (Chrysoperla rufilabris), sold as eggs or larvae, also feed on thrips, spider mites, mealybugs and scales. Predatory Midges (Aphidoletes aphidimyza) sold as an adult for greenhouse release lay eggs near aphid colonies where the orange larvae can then feed on sticky insects. Aphelinus abdominalis, a type of wasp, parasitizes aphids–laying eggs on their bodies, killing them–and eats the ones left unparasitized. As Bogash says, most biological controls do better with a sanctuary in which to stick around. When released in the greenhouse, they’ll quickly go to work, putting on quite a show. But as the number of aphids diminish, the good guys may also disappear.

THRIPS — Adults are found in blossoms, the larvae on leaves and deep in buds. Since they feed on all of the above, as leaves and flowers grow, they may look damaged, have a silver cast or appear streaked. Often black specks of excrement can be seen where the thrips fed. Thrips are tiny insects, just 1 to 2 mm in length with narrow bodies and fringed wings, and colors vary from straw-yellow to brown.

To find them hiding in flowers, try the old trick: tap blossoms over a sheet of white paper. This will dislodge them and, if you have a bunch, you’ll see what looks like black pepper on the paper. Penn State says the western flower thrip is the most likely to hit floral crops, particularly in a closed environment. And it doesn’t stay in the West, by any means.

Thrips are especially attracted to blue sticky traps, but they’ll also find the yellow traps. Look for the tiniest insect on the trap, and you’ll see thrips with their wings folded over their abdomens sticking to the trap–they put up no struggle. (Don’t say ‘aw’ until you’ve seen the damage they can do.) They appear spindle shaped with protruding wings. Hairs line the edges of the wings and they sport V-shaped antennae. Thrips love marigolds and can hit lisianthus in a wet year.

The best controls are good sanitation and a weed-free zone. Early detection is important because they spread various diseases such as Tomato Spotted Wilt Virus. Dr. Stanton Gill, with Central Maryland Research and Education Center, Maryland Cooperative Extension recommends Amblyseius cucumeris, tan-orange predatory mites, as a good biological control. Each predatory mite can consume up to 10 thrips per day and will survive on spider mites should you run out of thrips (more on spider mites below). Orius insidiosus, minute predaceous pirate bugs, are good beneficials, too, Gill says.

SPIDER MITES — Usually found on the undersides of leaves, especially near greenhouse heaters, vents and doors where it’s warmer and dry. Yep, they are a problem in hot and dry periods–they love water-stressed plants. Early sign of mite feeding is yellowish-white speckles on the upper side of the leaf as the chlorophyll is destroyed. Eventually, as populations increase, the whole leaf turns yellow.

Penn State says the mite, specifically the two-spotted spider mite, are minute arthropids with the largest adult female less than a millimeter in size. The body of the adult female and most immature stages is oval-shaped and usually appears light yellow to green with two large dark green spots on either side. All stages have eight legs except larval, which has six. Damage is caused by larvae nymphs and adults piercing the plant cells and sucking out the contents, leaving those tell-tale spots. Females lay eggs on the underside of leaves in fine webbing that the mites constantly produce. Now hear this: Each female can lay more than 100 eggs in a lifetime. Eggs can hatch in three days. Since they don’t have wings, sticky traps can’t catch them.

What to do? Don’t let weeds build up around your flowers and don’t let plants get water stressed. A good crop rotation helps, too. It’s harder in dry years, obviously. Bogash says spider mites can be a problem in low tunnels. He recommends using an insecticidal soap. Biological controls include Phytoseiulus persimilis, predatory mite; Feltiella acarisuga, Predatory Midge; Mesoseiulus longipes and Neoseiulus fallacis.

LEAFHOPPERS — Are small wedge-shaped insects that hold their wings slightly out. They pierce plant tissue and suck sap, weakening the plant, and happen to carry viruses. The best protection is protective covering (Reemay or agribon fabric) over hoops. Aster leafhoppers, which cause the dreaded aster yellows disease, are green yellow with six black spots and they grow to about 1/8th of an inch so you can barely see them. Both insecticidal soap and hot pepper wax are said to control leafhoppers. Gill says neem will help control heavy infestations.

BEETLES – Good sanitation and crop rotation are important steps in controlling beetles. We often just hand-pick them or squish them early in the season before they get to be a problem. Japanese beetles are slow to get up in the morning, so going out with a bucket of soapy water and flicking them in works wonders. Gill recommends neem for large problems. It represses the insects’ desire to feed.

CATERPILLARS — Caterpillars, immature butterflies and moths including armyworms, cutworms, leaftiers, leafrollers and loopers, have many natural enemies and are damaging only as larvae. The natural enemies include parasitic flies and wasps, damsel bugs, minute pirate bugs and more. Usually, caterpillars aren’t a major problem for flowers. If populations get out of control, and holes are being chewed in leaves (and large amounts of excrement are seen on foliage) there are three popular methods to fight back.

1. Find the buggers and pick ‘em off.

2. Apply the microbial insecticide Bacillus thuringiensis (Bt) will paralyze and destroy the insect’s gut wall cells, but the insect must ingest the Bt, and it may take up to three days for it to die as it chews away. Bt is sold under several trade names. Again, check the OMRI listing for allowable organic brands.

3. Use the popular biological control, richogramma, an egg parasitoid. The tiny wasps lay their eggs in the eggs of caterpillars. A new wasp emerges from the parasitized egg rather than a new caterpillar.

Garlic sprays and hot pepper wax are getting a lot of press; garlic for repelling insects (Bogash says it can deter bigger pests like rabbits and groundhogs until they get used to the smell), and hot pepper wax for killing a number of insects from aphids and spider mites to thrips and leafminers. Garlic spray (garlic oil and water) is said to keep insects off plants and the key is to use it as a repellent spray on the plant before the bugs arrive, to keep insects from ever finding a home. A variety of hot pepper products are on the market. Or you can make your own (see sidebar for a common recipe).

Learn your beneficials

You probably knew lady beetles are your friends. But did you know other predators, like ants and wasps, collect insect prey to feed their developing young? Did you know fireflies do more than light up the night — most are predators of slugs, snails and worms, according to Garden Insects of North America. The book even points out that some stink bugs are good. The Twospotted stink bug “specializes in beetle larvae such as the Colorado potato beetle” and the spined soldier bug primarily feeds on caterpillars.

Most ground beetles develop as predators. Soldier beetles can be important predators of aphids, mealybugs and other soft-bodied insects. Rove beetles are predators of insects found in soil. Even paper wasps feed their young on insects. (But, I can tell you first hand how aggressive they are in defending their nests, which they love to build inside high tunnels in places you don’t tend to see until it’s too late. Needless to say, they are no friends of mine!) There are many, many more. So know before you squish or you may be destroying a friend.

While there are pesticides and insecticides approved or allowable on a restricted basis by the Organic Materials Review Institute (OMRI) for certified organic growers, they should be used only as a last resort. Bogash advises keeping records of problems and scouting plants to discover pests before they take over.

All in all, if you use a reasonable crop rotation and have an awareness of insect problems that could occur, Bogash says growing cut flowers is nothing you can’t handle. I completely agree.