Integrated Pest Management at Cramers’: Focus on Dahlias

Integrated pest management, or IPM, as I understand it is simply the realization that if you are only using pesticides to control pest then you will not be as successful as you can be. Instead, those who use IPM rely on cultural methods in addition to chemical ones and this leads to less chemical use overall. At Cramer’s we take a lot of cultural practices into consideration when dealing with pests. The following is a non-exhaustive list of cultural practices that we use.

  • We have found that it is important to remove peony leaf residue from the field at the end of the season as the dried-up leaves can carry diseases over into the next season.
  • Zinnias are prone to powdery mildew. Rather than spray the zinnia field every week, we plant seeds every two weeks so that when one field becomes infected with powdery mildew we simply abandon it and move on to the next field.
  • Having enough space between plants is important with many crops such as ranunculus because the additional air flow keeps the leaves dryer which is a less favorable environment for diseases such as botrytis.
  • Fans in the greenhouse also increase air circulation. This reduces damping-off diseases of seedlings.
  • The raised ranunculus beds provide better draining soil for the roots which reduces root diseases.
  • Ranunculus beds are steamed to kill disease spores and weed seeds.
  • To some extent, amending the soil with compost improves the health of our plants and perhaps their ability to fend off diseases.

But today I want to focus on Dahlias. Dahlias, particularly dahlias grown in a high tunnel, are a spider mite favorite. In the past we really struggled to find an effective chemical control for the mite problem. And I think I know at least part of the reason why. Look at the picture below. This is what Naomi dahlias in a high tunnel look like. How do you penetrate that canopy with insecticides?

Several years ago, broad mites distorted the leaves of our blackberry plants and stunted shoot growth. In fact, the broad mites were a result of excessive spraying to combat the newly invasive species spotted winged drosophila. All that spraying killed the mites’ predators but not the mites and they flourished. So we purchased predatory mites. Predatory mites are the good mites that eat the bad mites that eat our plants. And they worked.

Anyway, it was only natural for me to use some of those predators on the dahlias. And when we discontinued the blackberry experiment, I continued to buy the predatory mites. I now release 3 times over the season and use 2 predatory mite species. The beauty of using predatory mites is that they easily penetrate the dense dahlia canopy. Besides that, once the predatory mites establish themselves they reproduce and stay with the crop which prevents flare ups of spider mite populations.

A common concern about using predatory mites is that they are easily killed by broad-spectrum insecticides. While this is partially true, I have found that occasional spraying for Japanese beetles or whatever is ok. Probably this is partly because these sprays only need to be focused on the top of the plant canopy, because that is where the flowers and pests are, while the interior of the plant serves as a. reservoir for the predatory mites. Also, we switch from our systemic insecticide with remains toxic for a long period of time to an insecticide which is toxic for only a short amount of time. This still kills the bad bugs on contact but spares the beneficial insects that might transverse that same area a little later.

Another common problem of dahlias grown in high tunnels is thrips. Thrips cause blemishes on the petals that are especially noticeable in white dahlias. Thrips also seem to be impossible to completely control with insecticides. I don’t really know why. Maybe because they are so small and can hide so deep in the flower, maybe because they have such a short life cycle, maybe because they hang out in the youngest parts of the plant (the flowers) which are least likely to have been sprayed, maybe because they are ubiquitous in the landscape….

Because I was already buying predatory mites and paying for shipping I decided to buy some minute pirate bugs as well. Minute pirate bugs (MPBs) are, you guessed it, predators of thrips. However, I think MPBs are more vulnerable to insecticides then the predatory mites. The solution is ornamental peppers; another Cramers’ crop. Every year I place the ornamental peppers centrally among the dahlias. Peppers are a good host plant for the MPBs because they provide pollen which is an alternative food source for MPBs and because we do not spray the peppers with broad-spectrum insecticides. Therefore, if we spray the dahlias and kill most of the MPBs, there is still a reservoir of MPBs in the nearby peppers. MPBs are comparatively mobile and can migrate back into the dahlias. Also, peppers in high tunnels always seem to attract thrips.

Both the predatory mites and the minute pirate bugs have been very effective. This means you are receiving a more consistently high-quality product than if we were relying on chemicals alone. And the product will have less chemical residue.


John Thomas

Production Managerblog

Philadelphia Flower Show

It’s an exciting season at Cramers’ Farm – starting with our revamped website design! This new forum allows me the opportunity to reach out and share news from time to time. I will also keep you up to date on local events where we will have our dried flower bunches, willows, wreaths, swags, bouquets and other wares available.

Speaking of events, attending the Philadelphia Flower Show is something that each of you should put on your spring bucket list! Each February, for the past 19 years, we start gearing up for the event, which has grown into the country’s largest indoor flower show. While we are there from 10am to 9pm for the show’s entire ten day run, we never tire of meeting so many interesting people and making new customers.

The Philadelphia Flower Show has something for every member of your family, including beautiful displays, food and drink tastings, special bridal events, and the list keeps on going. Of course, with more than 180 vendors, the shopping is my favorite part! Artists from across the country fill the Marketplace with handmade treasures and one-of-a-kind finds. My trip to the show isn’t complete without a stop at Copa Soaps. My friend, Toni, makes the best soap I have ever used! Give them a try and you will be a life-long devotee to her luscious bath bars.

Have a foodie in your group? The Reading Terminal Market is directly across the street from the convention center. This epicurean paradise is not to be missed. They have anything and everything that you could ever want to eat. A few of my favorites are Hershel’s East Side Deli, home of the best reuben on earth, DiNic’s roasted pork, and Meltkraft for artisan grilled cheese. My mouth is watering just thinking about a visit!

After a cold, windy, wet winter, we are all longing for spring. I guarantee this show will cure your winter blahs. Mark your calendar now for March 10 – March 19th. We can’t wait to see you there!

New Flower Varieties We Love

While I love to share our products with you, I am super excited to have a place to share what we are all about at Cramers’ Farm! We feel how we do is just as important as what we do. From growing techniques and post-harvest procedures to labor practices and employee relationships – we approach things a little differently than other farms our size. These unique practices carry over to every aspect of the farm, including our wide variety of flowers.

Today, I want to share the how behind the process of adding new items to our selection of flowers. Often, we discover new items in trade publications or by talking to other growers. Listening to suggestions, feedback and requests from our customers about specific crops provides valuable information too. Next, we dig around to research what is a good fit with our farm. Production requirements, harvest times, input cost, post-harvest treatments and return on investment are key players in making decisions. We have learned that just because you can grow something doesn’t always mean that you should. When an item passes the initial requirements, we try growing a relatively small amount to see how it goes.

This season we tried several different selections, some out of necessity and others to add diversity to our offerings. Here are our impressions of a few varieties:


Hibiscus Mahogany Splendor
I encountered this crop late last summer at Wollam Gardens in Jeffersonton, VA. (Thanks Bob Wollam!) The clean, beautiful foliage reminded me of a Japanese maple tree but with burgundy stem color. We sourced seed and grew it in several locations on the farm – both inside our high tunnels and outside in the field production area. Several growers shared that it can be finicky about re-hydrating after harvest. Even with excessive heat and drought conditions, it performed perfectly for us! Look for this beauty next season as we put it into full-scale production.

This one was driven by customer requests. (Thanks Tom and Persaud!) Years ago, we grew Scabiosa but stopped for various reasons. When it came time to look at it again, I was able to pick another grower’s brain about varieties and culture. (Thanks Jenny!) This year, we grabbed some mixed seed to see how it would perform on our farm. The plan for next year is to focus on solid color to meet market demands.

Dahlia: Souvenir de Ete and American Sun
Necessity drove trying these two selections. Our regular yellow dahlia (Karma series Ventura) was discontinued and we have been looking for a solid orange dahlia forever. Both of these tuber varieties produce tons of stems. The American Sun has a few drawbacks, thick stems and some russet color in the center on some blooms – but overall it’s a winner! Though the blooms are a little smaller than our usual dahlias, Souvenir has been pretty awesome with consistent production and a solid orange color. Both are likely to be back again next season.


Sunflower Pro-Cut Plum
This is a new offering from Germania in Chicago, the seed company from which we source most of our seeds. Corky Kane was nice enough to send us a small packet to try. While we really liked the look of this one and the shelf life is similar to other specialty suns, the real question is – where does it fit in our plan? We already grow dark brown Terra Cotta (our Cappuccino) and Pro-Cut bicolor (our Sundown). The Plum looks different, but is it different enough to add to what we already do? The small batch didn’t yield enough stems to send out to our customers for evaluation, so pictures will have to suffice. Consider this one a maybe for next season…

Dusty Miller
Customer requests and seeing it at another farm inspired us to try this one. Sadly, we were unable to attain enough stem length on the two varieties we grew. Plant mortality was also too high for our liking. I think with more TLC this could work, but realistically this is probably not going to make the cut.


Talk about a winner! We have been trying to work tunnel-grown ranunculus into our program for a few years and think we finally have it nailed! The production area is small in comparison to other programs, but the final product is amazing. We started a few years ago by sourcing domestic corms, primarily Gigi and LaBelle, with some success. Another grower saw what we were able to accomplish with the domestic stock and said we just HAD to try using Italian corms. Suffice it to say; Andrea knew what she was talking about! We placed our first order late in 2015, so we had to take what we could get as far as varieties and size of corms, but it still made a world of difference. We’re so impressed that we purchased another 4 season high tunnel, doubling our ranunculus production area from 2500 sq. ft. to 5000 sq. ft. for the 2017 harvest season. Corms will go in the ground in a couple of weeks. If all goes well, we will start cutting in late March. We are using the Elegance Series and the Success Series, known in the market as Cloni, in various colors.

This is the ultimate high demand item! The corms are expensive, they require a lot of management, they are gorgeous with tall stems and big heads – and as you would expect – the final product is priced accordingly. This season, every customer who got our ranunculus wanted an exclusive to buy all of our production. Although we are flattered, that doesn’t fit how we want to operate. The numbers will be very limited compared to most of our products. But if you are interested – and okay with possibly being disappointed AND sharing with others – call your wholesaler in late March to see how we are making out.


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