Summer Kickoff

In my mind, summer officially starts on Memorial Day weekend. BBQ’s get dusted off, farmers’ markets really gear up and roses fill the garden. Summer flowers are definitely part of this mix. These beauties come with baggage – quirks that affect quality. In last year’s summer Quarterly, I suggested you segregate crops into different postharvest categories: wilt-sensitive, bacteria promoters, ethylene sensitive types, bulb crops.  It can get confusing to have several different post-harvest procedures when you grow crops requiring different treatments, but if the crop brings good money, why not treat it in a way that makes sure your customers get knock-your-socks-off performance? What’s wrong with building a reputation that your blooms last!?
Specific questions from growers have me querying my Dutch colleagues regularly concerning postharvest “best practices” used in Europe and Africa. A few weeks ago, I traveled with two colleagues in California, visiting growers from San Diego to Arcata. Some of the following information comes directly from their questions about different products best suited for specific flowers.
Given the diversity of summer blooms, it’s important to consider a few things: Many varieties of summer flowers are knock-offs of well-loved garden blooms, and often vase life may not be the breeder’s primary consideration for developing them. Also, lots of summer flowers exude enzymes and substances that block water uptake. This is where chlorine and hydration solutions make an important difference. Hydration usually happens best when sugar is not part of the formula. Avoid using flower food for hydration. Instead, use a commercial hydration solution for best results. Choose one that allows you to reuse your solution for several days. It’s expensive to dump after an overnight drink!


If chlorine is your biocide of choice, keep in mind that its effectiveness is short lived. Less than 2 days! Just because you can smell it, doesn’t mean the chlorine is still active. Even the slow-release chlorine pills have a shelf life of 18 months. My tech buddy, Rolf, told me that even laundry chlorine (soduim hypochlorite) is not active after the concentrate has sat around in your basement for more than 6 months. Regardless of the type of chlorine, it loses its active power once it reacts—whether it is Clorox or a slow-release type, there is no residual effect.  

Hydration Solutions

Flower hydration solutions are based on quaternary ammonium products, aluminum sulfate or citric acid. Regardless or the brand you choose, mix it according to instructions! Use opaque buckets and hold ready-to-use solutions in the cooler between uses, and cover it. Commercial hydration solutions do have a residual effect and can be reused for several days depending on the bio-load that passes through the buckets. Check the label or ask your supplier how long the product holds bacteria in check.

Choosing the right solution for your needs has a lot to do with how you answer these questions:  

1.  How fast do your turn your flowers?
One to one and a half days? Or is your rotation more like 2-5 days? Use chlorine if you turn flowers fast (less than 2 days) and sell from the same buckets you harvest in. Use a hydration solution if you rotate your flowers more than a day. Hydration solutions are more stable and can be reused to defray costs. Recommendation: Blend your mixture for best results! Use chlorine for initial bacteria control the first day,  and an aluminum sulfate-based hydration solution for bacterial control the next 6 days.
2.  Do your customers know what solution to use once your flowers leave your hands?
If you sell to wholesalers or florists, tell them to give your flowers a fresh cut and process into a low-sugar flower food. Floralife Professional, Syndicate Sales Aqua-hold and Chrysal Professional #2 are examples of low-sugar processing solutions. Remind wholesalers to have buckets prepped for your dropoff so flowers don’t sit out dry too long. If you sell directly to consumers, tell them to use a flower food packet—it’s 1,000 times more efficient that water, sugar and aspirin!
3.  Do you work with clean buckets?  
If your buckets are dirty to start with, the biocides in the solution (both long term and short term) are depleted very fast trying to keep bacteria in check. When you wash buckets, use a biodegrade detergent and Clorox to maximize your efforts. Wash both inside and out to avoid cross-contamination when stacking.
 4.  Do you store cuts in a cooler?
Hydration solutions can be reused up to 5-7 days depending on number of stems that pass through, if the flowers are held in the cooler and if you started with a clean bucket. Studies show that removing the field heat improves vase longevity. Make sure there is good air flow so condensation can evaporate within bunches and from inside sleeves. Keep your cooler floor as dry as possible to avoid botrytis breeding grounds.
5.  Do you harvest flowers at high temperatures (over 80F)?  
These flowers respond well to slow-release chlorine (not Clorox!) and/or an aluminum sulfate-based commercial hydration solution. If so, you need a hydration solution that really boosts flow into wilting stems that are exuding a host of bacteria-loving enzymes as part of harvest stress. Since many summer flowers in fact produce exudates, staying on top of the bacteria issue is critical to insure flowers perform and hold in the vase. One idea is to try blending solutions. Using the dilution guidelines listed on the labels, try adding a slow-release type of chlorine + aluminum sulfate-based hydration solution. This blend provides double duty—chlorine kills bacteria populations that explode immediately after harvest. When the chlorine is finished after 24—36 hours, the aluminum sulfate-based hydration formulation takes over. The second solution continues to control bacteria while lowering the pH and boosting flow up the stem.

Postharvest guidelines:
These flowers respond well to slow-release chlorine (not Clorox!) and/or an aluminum sulfate-based commercial hydration solution. For best results, blend your solution = slow Chlorine + AlSO4-based hydration  solution.

GerberaMarigoldsPhlox Zinnia 

These flowers respond best to a quaternary ammonium-based hydration solution (rather than chlorine or AlSO4-based)

Asters (All crops that look similar to asters) 
•Limonium species
•Sunflowers-cut w/color

Sometimes, sugar is good. Earlier, I said that hydration happens best when the solution has no sugar, but some flowers respond well in low-sugar solutions. The sugar provides the energy needed for florets to continue opening. These solutions acidify the water, keep it pollution free and provide a minimum amount of sugar. Remember to measure when you mix or don’t bother wasting your time and money.

Flowers needing a low-sugar pretreatment:
• Calla  • Lilac  • Stock  • Viburnum
• Lisianthus  • Mimosa  • Sunflowers-real tight cut
Flowers needing high sugar in postharvest:
• Protea – prevents foliage blackening
• Tuberose – blend slow-release chlorine or AlSO4 hydration solution overnight, transfer into high-sugar flower food to get blooms open.
• Sanitize your tools more than 2 times a day to avoid cross contaminating stems as you harvest.
• Get flowers under shade and into a solution containing biocides ASAP.
• Make sure the first drink is as clean as possible and bacteria development is controlled.
• Mix solutions with cold water, or mix day ahead and cool down buckets before cutting into them.
• Call your supplier if you have questions – your success is our success!
Test Protocols

Try several different solutions to see which give the best response for your water, harvest temperatures and varietal choices. Tests need not be complicated: Set up various solutions in different vases according to instructions. Label and date with appropriate information. Place at least 5 stems per vase – make sure the stems are similar in size and bud count.
Treat flowers in the same way you currently handle them, e.g. leave in hydration solution the same amount of time that simulates your current rotation practices. After that time passes, transfer blooms into same type of solution used by your customers; wholesalers/retailers usually use low-sugar processing solutions, consumers use full-load flower food solutions made with the packets. Do make sure to use the same solution for all vases once you move blooms from post-harvest to wholesaler stage. You want to compare apples with apples. What you give as a first drink is highly instrumental to the end success of the bloom’s end performance. Often, appreciable differences don’t show up until the last stages of a flower’s life.

Friends we remember –

Have you ever known someone who, although you were not in daily contact by any means, every time you called it was like you had just spoken last week? That describes my experience knowing Philip Katz. Philip worked for PanAmerican Seed. His official title was new varieties production manager, but I called on him for all kinds of help and information. We had many great discussions about everything from why it was hard to sell growers on new flower varieties that were perfectly suited for the bouquet market (like the hybrid delph and Peloric snaps) to logistics for routing a group of Colombian growers through the California seed trials. I fondly recall laughing over beers in Holland as he told stories comparing Dutch growers’ robotic fascination with Colombian pragmatism and Ecuadorian intrepidness. Philip was a wealth of technical, practical and real-life information, but experiencing his humor was the real joy of knowing him. Goodbye Philip. We’ll miss you. Thanks for all your help over the years!

Gay Smith