Boone County Purdue Extension, 1300 East 100 South, Lebanon, IN 46052 [email protected] 765-482-0750

Growing Dahlias

On May 20th the Zionsville Cultural District distributed free dahlia tubers to the public at the Zionsville Farmers Market. The purchase of these dahlia tubers was made possible by a 2023 Boone County Master Gardeners Education grant.  The ZCD team explained how to grow dahlias in this area and provided instructional handouts to accompany each dahlia tuber.

Zionsville has a unique historical relationship with dahlias. Nearly a century ago, Zionsville had the nickname “Dahlia City” because there were two village nurseries selling dahlia tubers and other flowers throughout the country as a mail order business.  One of those nurserymen, Fred Gresh of Parkway Gardens, actually won the coveted Gold Medal Award at the 1933 Chicago World’s Fair from the American Dahlia Society for his own hybridized dahlia called “Zion’s Pride”.   Unfortunately, this large, lemon-yellow dahlia is no longer in existence.  The town of Zionsville pays tribute to its historical name “Dahlia City” with a mural on the traffic signal box at the SE corner of 106th St and Zionsville Road.

Dahlias are some of the garden’s biggest and most spectacular flowers in a garden.  They can be grown in zones 3-11 but in zones 3-7, the tubers must be dug and stored to survive the winter.  Boone County is located in zone 5 so gardeners must dig and store their tubers if they are to grow again next year. Dahlia tubers must be planted in a sunny, well drained area of the garden when all danger of frost has passed.  This is usually around Mother’s Day or May 10-15th.  They need a minimum of 6 hours of sunlight per day but really thrive with more sunlight.   Dahlias need a hole 6-8” deep and before planting, incorporate some compost and all-purpose fertilizer. When planting, spread the tubers out and make sure the crown is upright. Backfill with soil but make sure the crown of the plant is no more that 1-2” below the soil surface.

Dahlias should have about 1” of water per week and starting in July, also include a monthly application of water-soluble fertilizer. When the plant is about 10” tall, pinch off the plant at the center stalk to encourage more side shoots and more blooms. . Make sure it has at least 4 sets of leaves.   Staking the dahlia may become necessary if the plant grows more than 36” tall or the plant starts bending with the weight of the blooms.  Deadheading the spent flower stalks will encourage the plant to keep on producing more blooms.

Dahlias are to be dug when the plant is darkened by frost.  Cut the top back to 4-5 inches and gently lift the tubers out of the ground with a fork or spade.  Remove the soil around the tubers by hosing the tubers gently with water and allowing the tubers to completely air dry for several hours.  At this time, you can divide the tubers making sure that each tuber has an eye.  Store the tubers in a dry, cool, frost-proof place, wrapping the tubers in clumps of newspaper, or boxes with sand, sawdust, peat moss or vermiculite.  It is important that the tubers don’t shrivel or decay during this dormant period.

Periodically check the tubers in storage and when you start seeing new shoots developing, you can start potting them up or if it is past our frost-free date, you can plant them directly in your garden again.


Zelonis, Mark, “Zionsville The Cultural City”, Zionsville Cultural District handout given at the Dahlia Giveaway Zionsville Farmers Market, May 20, 2023

“Tips for Growing Dahlias”, Zionsville Cultural District handout given at the Dahlia Giveaway Zionsville Farmers Market, May 20, 2023

Dana, Michael N. and Lerner, B. Rosie, “Winter Storage of Geranium, Canna, Gladiolus, Caladium, and Begonia” Purdue University Cooperative Extension Publication HO-85-W, July 2005.

Winter Sowing

Now is the time to get your supplies ready for winter sowing of seeds that need stratification or cold, moist conditions in order to germinate.  The sowing time in our zone 5 area for these seeds begins with the Winter Solstice, December 21st

Look for seeds that are described with the following terms: reseeds; colonizes; self-sows; hardy seeds; seedlings can withstand frost; sow outdoors in late autumn or early winter; sow outdoors in early spring while frosts may still occur; needs pre-chilling; requires stratification.  This group includes native plant seeds such as milkweed, black-eyed Susan, purple cone flower, liatris, lobelia, penstemon, and cool season annuals such as snapdragon, pansy, and nasturtium.

Start with a clean milk jug in which you have drilled holes in the bottom of the container for drainage and also along the top for ventilation. Discard the milk jug cap.  Mark a circular line 4″ above the bottom of the jug  and cut along your line leaving the handle area intact creating a hinge.  Place a coffee filter in the inside bottom of your jug and then fill the bottom half of your jug with potting mix.  Moisten the soil.  Plant your seeds according to package directions and pat them down so they make contact with the soil.  It is a good idea to plant only 1 variety of seed per jug.  Label the inside with a marker identifying the seed variety and date of sowing.  I found that cut up yogurt containers or blind slats make good markers. Seal your jug with duct tape and you now have a mini-greenhouse.

Cut milk jug filled with moist potting mix, seeds and plant marker. Notice the hinge.
Sealed milk jug with duct tape

Put your containers outside in the winter sun, periodically checking to make sure that you see condensation droplets on the inside of the milk jug.  If you don’t see condensation, mist the soil.  It’s also a good idea to corral your jugs in a crate so that the wind doesn’t carry them off.

Allow Mother Nature to go through its freeze, thaw, snow and rain cycles and in the early spring check for germination. Once the seeds have germinated, start opening the jug for more ventilation to avoid overheating.  When the air temperatures reach 60oF, discard the top of the milk jug.  These plants won’t need to go through the hardening process since they grew under natural conditions.

Barbara Burkhardt

Boone County Master Gardener


“Starting Seeds in Winter”   Penn State Extension

“What plants can I winter sow?”  University of Missouri Extension

The Great Eggplant Experiment and Cover Crops

A team of Boone County Master Gardeners working at the Lebanon Church of Christ Community Gardens decided to try an experiment in the eggplant raised garden.  Half of the bed was planted with ‘Black Beauty’ Eggplant starts.  This was their control group.  The other half of the bed, the experimental group, was planted with the same variety of eggplant and Crimson clover seeds were added at a later date.

Their results were astonishing!  The control groups plants grew about 2 feet high while the experimental group’s plants grew 3 feet high.  In addition, the experimental group overall’s harvest produced a higher yield in number and size of the eggplants.

Figure 1. Control Group Eggplant averaged 2 ft tall
Figure 2. Experimental Group Eggplant averaged 3 ft tall
Figure 3. Control group’s harvest in one day
Figure 4. Same day’s experimental group’s harvest – that day the number was the same but the bigger size.

Why did this work?  Clover belongs to a group of plants called legumes.  Peas, soybeans, alfalfa and peanuts are also examples of legumes.  Their roots contain visible nodules that house nitrogen-fixing Rhizobium bacteria.  Through a mutualistic relationship with the legume plant, these bacteria are able to take nitrogen from the air and convert it into ammonia and other plan-using nitrogen compounds, thus fertilizing the surrounding plants.  In other words, Master Gardeners added plant-fertilizer making factories!

Figure 5. Nodules with Rhizobium nitrogen-fixing bacteria

Crimson clover is a good choice as a cover crop as it will die back when the ground freezes, thus the plant will decompose adding nutrients to the soil before spring planting the next year.

On a side note, as your garden starts to wind down from the summer harvesting season, NOW (mid-September – October) is the time to plant a cover crop mix.  Such mixes usually include three different types of seed – Brassicas with taproots, legumes and grasses.  The taproot Brassicas include oilseed radishes and turnips.  Their deep roots create inroads between the soil clumps thus reducing soil compaction and allowing water to penetrate deeper into the soil.  Legumes will add nitrogen nutrients and grasses, such as cereal rye, prevent wind and water erosion of the bare soil and will become a green manure when tilled in.  This will add needed organic matter.   If planting a fall cover crop, a home gardener should look for a mixture that will die when the ground freezes, so decomposition occurs before the soil is tilled for spring planting.

Barb Burkhardt


Reece, Jane, Urry, Lisa, Cain, Michael, Wasserman, Steven, Minorsky, Peter and Jackson, Robert.   2011.  Legumes.  Campbell Biology, 9th Edition. San Francisco: Benjamin Cummings. p. 794-795.

Curt Emanuel. “Using Cover Crops in Home Gardens” August 20, 2020. Purdue University Extension presentation

Doug Higgins and Kristin Krokowski. “Using Cover Crops and Green Manures in the Home Vegetable Garden”, University of Wisconsin Garden Facts #XHT1209, UW Extension.

When Should I Plant My Garden?

One hears that tomatoes, and tender flower annuals should be planted when there is no danger of frost. Often the date of May 10th or 15th is mentioned as the last frost date in Central Indiana.  But there is another method called Phenology or using nature’s cues to determine when to plant and harvest.

Some examples cited by Robin Sweetser writing for the Farmers Almanac are:

This time of year we are all excited to plant our tomatoes and petunias but we may have to restrain ourselves and watch the weather forecast.

Gardening Tip

How Do You Know the Correct Time to Till your Garden Soil?

Do the Tennis Ball Test. Dig down in your garden about 4-6” and pack the soil into a tennis ball.  Then drop the ball onto the ground.  If it breaks apart easily into small pieces, the soil is dry enough to till. 

Kurt Lazone – Purdue ANR Extension Educator – Parke County

Indiana Winter Farmers’ Markets

By Holly Catron, Boone County Master Gardener

Have you experienced an Indiana winter farmers’ market? Here is an opportunity to address food insecurity and improve nutrition in our communities.

We moved to Fishers in February, two years ago. I was excited to visit my first winter market. Would there be vegetables? What else? Winter markets can improve the local food economy and elevate the nutritional health of a community. They represent a partnership between farmers, food artisans, and customers. 

The market was held in the park community building. Vendors of all sorts were spaced around the room. The smell was delightful, with Mathoo’s Egg Rolls front and center. There were tables of baked goods, eggs, a meat vendor, wine, jams and honey, cider, and much-to-my-delight, vegetables! I strolled through with a big smile on my face, filling my shopping bag with goodies, and chatting with the vendors. I munched on my warm eggrolls on the way out.

Some vegetables are just coming into season as the summer markets wrap up. This creates a problem for the local farmers and an opportunity for a market. Further, those late-autumn veggies like squash, beets, and carrots can be stored, as can honey, cider, and canned or frozen foods. Frozen meat is always in season, as are eggs, although production may fall off as the light diminishes. And don’t forget dried options and fresh microgreens.

Many Indiana vegetable producers have invested in hydroponic systems and grow in warm buildings, while others have hoop houses or greenhouses, sometimes heated. These extend the growing season and allow a steady stream of greens, and really any kind of vegetable throughout the winter months.  

According to the 2019 National Farmers Market Managers Survey, there were 8,140 markets operating in the U.S. in 2019. Of those, 21 percent operate year-round. Of the 4,076 markets that accept Federal Nutrition Programs, 78.7 accepted Supplemental Nutrition Assistance Program (SNAP) benefits.

So, what does that mean? If the market operates under the same entity in the winter as the summer, they could already be eligible to offer SNAP at the market. If not, they may be able to apply. Any of the food items mentioned above, with the exception of the eggrolls, can be purchased using SNAP benefits.

The winter market provides another opportunity for a match program, kids’ activities or a club, nutrition education, and food demonstrations. Space may be limited, but many of the same initiatives offered in the summer can be applied to winter markets.

Enjoy a stroll through a winter market today!

Here are some links you may enjoy.

National Farmers Market Managers Survey:

A list of the Indiana farmers’ markets (some specify year-round):

Bloomington Winter Market:

Fishers Fall Farmers’ Market:


Broad Ripple:

Early Summer Garden Tips

With so many first-time vegetable gardeners this year I want to provide some tips on issues to look out for and practices to help your garden during the early portion of summer.

Tomatoes: Tomatoes are the most popular vegetable crop grown in Indiana home gardens. For those who have not raised tomatoes before, there is a risk of the fruit developing cracks as it develops. There are some pests that may cause this however this usually occurs when we have alternating dry and wet periods during fruit set. As the plant takes up water, the fruit swells, then shrinks as the plant dries out, resulting in cracks. To mitigate this, once fruit begins to develop, provide supplemental water to help maintain soil moisture. If you have not done so, using a mulch to help retain moisture can also help. The cracks themselves do not make the fruit unsafe to eat once you cut them out however the wounds do provide an avenue where other diseases may enter.

In-season fertilization also helps tomatoes. Ideally, sidedress about 1/3 pound of actual nitrogen (N) per 100 foot of row three times during the growing season:

  • One to two weeks after the first fruit set
  • Two weeks after picking the first ripe fruit
  • Six weeks after picking the first ripe fruit

It is important not to over-fertilize tomatoes. Too much fertilizer can result in a plant with great vegetative growth but no fruit. Basically the plant receives a lot of fertilizer and doesn’t realize that the growing season may be ending and never begins its reproductive cycle.

Sweet Corn: Sweet corn also benefits from nitrogen fertilizer during the growing season. For intense management you can apply fertilizer as many as three times however the most important application is to sidedress 1-1.5 pounds of N per 100 feet of row at growth stage V8. V8 means when you can see eight leaves on the plant.

Sidedress means placing nitrogen in a band near but not in the row where the plants are growing. Use the handle of a garden tool such as a hoe or shovel to create a two-inch deep channel or groove about two inches away from the row. Place your granular fertilizer in the channel and cover it up. For liquid fertilizer, dribble it into the channel. It is best to apply either when the soil is moist or before rain is expected. For best results, place N on each side of the row. If your tomatoes are spaced far apart, create a ring around the base of the entire plant.

Cucurbit Pests: Cucurbits include squash, cucumber, melons, cantaloupe, pumpkins, and other similar crops. While most cucurbit diseases show up later in the season, the pests that cause them should be controlled starting now.

Squash bugs begin appearing in late June. They feed on all parts of the plants – leaves, stems and fruit. When they feed, they inject toxins from their saliva into plants which damage tissue. While noticeable on leaves, the most serious damage occurs when they either destroy a stem or damage fruit.

Squash bug adults are difficult to control so your focus should be on the nymphs. To see if you may have a possible squash bug problem, look for clusters of copper-colored eggs on plant stems or the underside of leaves. If you have more than one cluster per plant be prepared to control them once they begin hatching. While you may apply pesticides, so long as you are willing to regularly monitor your plants, you can usually control them by knocking the nymphs off into a bucket of soapy water. Squash bugs can be a serious pest of all cucurbits but particularly squash, pumpkin, melon and cucumber.

Squash Bug Larva
Squash Bug Adult

Cucurbit growers need to be alert to the presence of striped cucumber beetles. These are very distinctive insects with black heads and yellowish bodies with three black stripes running down their wing covers. They can sometimes cause enough damage by feeding on leaves and stems to result in problems however often the most serious damage shows up later in the growing season as striped cucumber beetles carry and transmit bacterial wilt, a devastating plant disease.

Striped Cucumber Beetle

It is impossible to treat bacterial wilt once a plant is infected. The most effective method is through control of cucumber beetles. Control recommendations vary with each individual crop. For additional information refer to Purdue Extension publication E-95-W, “Managing Striped Cucumber Beetle Populations on Cantaloupe and Watermelon” by Purdue Extension Entomologist Rick Foster. It is available online at:

GARDENING: A Guide for Community Gardens during the COVID-19 Pandemic

March 25, 2020

Raised Bed Garden

Community gardens offer many benefits — gardening knowledge, social bonding and, most importantly, the increased production and consumption of nutritious, fresh and locally grown fruits and vegetables.

Amid the COVID-19 pandemic, people may be unsure if it is safe to visit a community garden or even if the garden remains open. Garden access may be contingent on its role in carrying out essential functions as designated by Indiana’s shelter-in-place order. (These regulations also are subject to change amid fluid developments.)

It is essential that garden leadership teams clearly and quickly inform all audiences of any policy changes.

This guide offers ideas and guidance on:

  • Best practices for community garden management during the COVID-19 pandemic
  • Additional cleaning/sanitation precautions to utilize in community gardens
  • Recommendations on being a safe, responsible visitor at a community garden

Following these recommendations, along with the use of common sense and caution, can increase the likelihood that community gardens will remain accessible.

Garden Types

Knowing a community garden’s type is key to understanding its potential role in essential functions.

  • Sharing Gardens: Also known as food pantry gardens, these gardens operate on the principles that those who use them help maintain them and only take food that they know they will use.
  • Allotment Gardens: Also known as community gardens, these gardens offer individual plots on which community members grow and harvest produce for themselves and their families.
  • Demonstration Gardens: Also known as educational gardens, these gardens host instructions on gardening practices, healthy living and plant science, with produce donated to food pantries or cooking classes.

To make decisions on garden availability and access, Purdue Extension advises that community garden leadership consult with local government leaders to determine if their space is considered essential.

Best Practices for Community Garden Management During the COVID-19 Pandemic

If a community garden is considered an essential space, garden management should immediately implement the following practices for any garden visitors, volunteers or maintenance groups:

  • Communicate to all potential audiences that they should not visit the garden if they feel ill
  • Do not allow anyone with signs of illness on the site; volunteers may need to control entrance
  • Postpone community events/tours, as well as carry-ins, potlucks or self-serve food
  • Leave garden gates open during hours of operation to avoid frequent contact
  • Remove or cordon off public benches or picnic tables
  • Limit the size of work groups to 10 people or fewer
  • Stagger times for arrival and availability to reduce crowds
  • Enforce social distancing guidelines of remaining at least 6 feet apart at all times
  • Ask volunteers to bring their own tools or assign select tools and tasks to individuals
  • Create and implement procedures to sanitize tools before and after garden work
  • Undertake additional cleaning and sanitation protocols and recommendations, such as
    • Regular cleaning of contact surfaces (doorknobs, padlocks, water spigots, gates, etc.)
    • Hand-washing or hand-sanitizer stations
    • Reminders on how to properly wash hands (i.e., thoroughly and for 20 seconds)
    • Encouragement of visitors/volunteers to wash or sanitize their hands

The Environmental Protection Agency website offers a list of EPA- registered disinfectant products for COVID-19. Always consult product label guidelines to determine if disinfectants are safe and recommended for use in a garden. 

Garden leadership should communicate all new or amended policies through:

  • Signage at the garden entrance, near water sources and wherever tools are stored
  • Emails to gardeners that request a response of confirmation that all policies are understood
  • Social media or other methods to reach community members who may not be on a mailing list

Best Practices for Garden Visitors

If a community garden remains open to visitors beyond volunteers/maintenance crews, visitors should take additional precautions to allow safe enjoyment and minimize the potential spread of COVID-19.

  • Do not visit the garden if you are feeling ill or showing signs of illness
  • Wash/sanitize your hands before and after visiting the garden
  • Follow all new and existing garden policies
  • Maintain social distancing (6 feet between individuals)
  • Limit interactions and time spent in the garden
  • Minimize contact with surfaces (e.g., doorknobs, gates, latches, railings)
  • Wash your hands and any produce you bring home to reduce contamination


Terri Theisen, Urban Agriculture & Horticulture Educator, Purdue Extension – Allen County

Jackie Hoopfer, Purdue Extension Advanced Master Gardener and Display Garden Coordinator in Allen County

Veronica Jaloma, Community Wellness Coordinator, Purdue Extension – Lake County

Rebecca Koetz, Urban Agriculture & Horticulture Educator, Purdue Extension – Lake County

Rosie Lerner, Purdue Extension Consumer Horticulturist

Karen Mitchell, Agriculture & Natural Resources Educator, Purdue Extension – Tippecanoe County

Nathan Shoaf, Purdue Extension Urban Agriculture State Coordinator

Andrew Smith, Urban Agriculture & Horticulture Educator, Purdue Extension – Vanderburgh County

Sunflower Head-Clipping Weevil

At a recent Master Gardener meeting, Susan Kovach asked if anyone had the problem of purple coneflowers having their flower heads almost cut off and left hanging toward the ground. Four summers ago I noticed this problem in my garden. 

This is the work of the sunflower head-clipping weevil (Haplorhynchites aeneus) a well-documented pest of cultivated and wild sunflowers in the Great Plains. Sunflowers are the preferred plant but the weevil also attacks purple coneflowers and other plants in the aster family. 

The shiny black to brownish-black weevil is a little over 1/4″ long with the measurement including an exceptionally long, curved snout.  As with all weevils, the mouthparts are located at the end of their snout.  The females insert their snouts and chew a ring of holes around the stem one to two inches below the flower head. The flower stem is not completely cut; this weakens the stem to the point where it eventually breaks over, leaving the flower hanging by a thin strand of tissue.

There is only one generation per year. Only females are thought to perform the clipping behavior. “The female enters the flower to feed on the pollen and lay eggs.  The flower eventually falls to the ground, eggs hatch and the immature weevil, a worm-like larvae, moves into the ground for winter.  Next spring the larvae pupates, then transforms into a weevil and starts feeding on the flower stems in mid-summer.” (Melinda Myers website) It is speculated that the weevil’s odd head-clipping behavior reduces larval exposure to plant defense chemicals and also prevents other insects from competing for the seed head prize.

Removing the flower heads that are still hanging as well as those that have dropped to the ground can help to reduce populations next year. I have found that if the flower head has turned brown before it drops off, it is often difficult to find it on the ground. When removing the flowers from the stem, hold a bucket of soapy water under the flower and clip the rest of the stem, dropping the flower into the bucket. This may help to kill any adults that are feeding in the flowers, reducing the populations and further damage to other plants. It also kills the larvae and prevents them from further developing.

In past summers I have removed the damaged coneflowers and stems well below the weevil cut, put them in a plastic bag, sealed the bag, and put the bag in the garbage. Initially I cut the damaged part of the stalk just below the weevil cut leaving several inches of stem. When checking a few days later for further damage, I was not sure if I had removed the damaged stem and flower or the flower had dropped to the ground leaving a flowerless stalk. To solve this issue, I now cut back to the leaves below the weevil cut and I know that the flower head has not dropped to the ground. I tour my garden about every three days and carry a bag and clippers with me to remove any new damage. This minimizes damage and reduces future infestations.  

Cutting off the damaged part of the plant and disposing of it is the best garden control method for the sunflower head-clipping weevil. Pesticides are not a good option. Pesticides should not be used on a plant in full bloom because of the risk of killing pollinators.

This weevil has been at work in Indiana for several years. The first mention I found of the weevil causing damage in Indiana is in an August 2011 Hoosier Gardener article by Jo Ellen Meyers Sharp. Other websites report the weevil in Illinois (2007) and Ohio (2009)

Jane Savage

Note. This article is a compilation of information the websites listed below. (Kansas State University website) (good pictures – Ohio State University)

Tomato Leaf Spots

Tomato Septoria Leaf Spot Disease
Tomato Leaf Spot Disease

I’ve been surprised – and gratified – at how few calls I’ve received about tomatoes this year. Let’s face it, this has been as lousy a year for growing them as it has been for most other crops. In a year like this I often am not able to offer much help. But since they are the vegetable most commonly grown in Central Indiana home gardens I want to mention two diseases they are particularly susceptible to.

About this time of year two common fungal leaf-spot diseases often appear. Septoria leaf spot and early blight are both characterized by brown spots on the leaves. Septoria usually appears earlier in the season than early blight and produces small dark spots. Spots caused by early blight are larger and often have a distorted “target” pattern of concentric circles. For each disease, heavily infected leaves eventually turn yellow and drop. Older leaves are more susceptible than younger ones, so symptoms generally first appear at the bottom of the plant and progress higher.

These diseases can spread rapidly so it’s important to scout for symptoms. Plants usually become susceptible when fruit is about the size of a walnut. If you see symptoms, fungicides can help prevent their spread. Be sure to apply fungicide to both upper and lower leaf surfaces, and reapply if rainfall removes it. Chlorothalonil is a good choice for fruiting plants because most products have no harvest waiting period, meaning that fruit can be harvested once the spray is dry.

Chlorothalonil is an ingredient in several products. Be sure to start protecting plants when the disease is first seen. It is virtually impossible to stop it on heavily infected plants. As with all pesticides, always read and follow all label directions.

Several practices can help with disease prevention. Mulching, caging, or staking keeps plants off the ground. Better air circulation allows foliage to dry quicker than in plants allowed to sprawl. Mulching also helps prevent water and soil from splashing and carrying disease spores to the plant.

You can reduce many diseases by following proper sanitation at the end of each growing season. This includes removing and disposing of any plant material. Composting, if done properly, will also destroy disease organisms.

If you experience either disease and you are able to, consider rotating tomatoes out of that area of your garden. Other plants such as peppers, eggplant and potatoes are also susceptible so avoid replacing tomatoes with these crops.

Frequent rainfall and high humidity are conditions which favor the development of these diseases. We’ve had an abundance of both this year. For additional information on these and other tomato diseases, see Purdue Extension Publication “Five Steps for Healthy Garden Tomatoes,” by Purdue Extension Specialist Daniel S. Egel. It is available online at: