Home Blog Harvest & care tips for 10 heat-loving summer blooms
July 15th 2015

Harvest & care tips for 10 heat-loving summer blooms

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IMG_7679Here on our farm in the Skagit Valley and in large swaths of the Western U.S., the super hot, dry weather has sent many growers scrambling to tend and harvest their stressed fields and gardens. While many flowers bloom abundantly in this type of weather, to get the longest life out of your flowers–especially with the added stress of high temperatures– it is important to know the best times to harvest and strategies to care for your fresh cut blooms right after they are cut.  (In flower farmer speak, this is referred to as “stage of harvest” and “post-harvest handling.”)

Here are a few of my favorite tips to help you beat the heat and get the best vase life from 10 high summer flower varieties.

Heat Loving FlowersZinnias:  Harvesting zinnias at the right stage is essential to getting a long vase life.  Harvest too soon and the stems will bend and droop; wait too long and the blooms fade quickly.  A really simple way to see if your zinnias are ready to harvest is by doing the “wiggle” test.  Simply grab the stem about 8 inches below the flower and give it a gentle shake.  If it’s immature, the stem will be soft and bend easily.  If it is ready to harvest, the stem remains stiff and upright when you wiggle it.  It’s time to cut!  Cut deeply on the plant to get a long, strong stem. Remove the foliage and don’t be afraid to cut off side shoots on the main stem you just harvested.  Zinnias are a  “cut and come again” flower, so when you cut the plant “hard,” it responds by sending out even more long, strong stems all season long.

We cut zinnias directly into fresh clean water with a drop of chlorine or a CVBn pill added to the water.  The little conditioning pills are often labeled for gerber daisies, but they are great for any of the “dirty” flowers with hairy stems that easily collect dirt and bacteria that can muck up the water. Zinnias love heat and consistently bloom during the hottest season of the year and their love of heat also extends to post-harvest care.  They’re one of the few flowers we do NOT put in the cooler to condition prior to delivery or design work. We simply store them in a dark, shaded area of our studio out of direct sunlight. If you follow these few simple steps, you’ll have beautiful long-lasting blooms that hold up 7-10 days in a vase.

Note:  Commercial flower food is generally not approved for certified organic production.  If you are certified, using bleach or boiling water and proper stage of harvest are really key. If you are not certified organic, CVBn pills and other hydration and conditioning solutions are worth the additional investment to ensure maximum vase life for your flowers.

Heat tolerant flowersBasil:  During the height of summer, our mixed bunches of flowers for grocery store customers almost always include at least a stem or two of Cardinal, Oriental Breeze, Lemon or Cinnamon basil.  I harvest basil when the stems begin to harden and the flower heads start to form and then treat them with Quick Dip (non-organic) or boiling water (organic alternative) to prevent them from wilting.  Be sure to harvest during the cool of the morning or evening as these guys wilt very quickly. Like zinnias, basil doesn’t like the cold, so keep them out of the cooler to complete their conditioning. Stems should last 7-10 days, and will often root in the vase.

IMG_3572Scented geranium:  The fuzzy, fragrant leaves of scented geraniums are a must-have foliage for bouquets, but they can be wilt-prone if you don’t follow a few basic steps.  I always try to cut scented geranium first thing in the morning before the heat of the day is upon us, cutting only the firmest stems.  After cutting them into cool water, I let them rest and condition for 3-4 hours before arranging them. If stems are still wilting, dip the bottom 2-3″ in boiling water for 5-7 seconds or dip them in Quick Dip.

IMG_5579Hydrangeas:  Hydrangeas are another flower that tends to be wilt-prone. The stage of harvest is perhaps less important than how you hydrate it after it is cut.  My trick is to cut when it is cool and to then use Quick Dip instant hydration solution or, for organic production, cut them into hot water.  I know other flower farmers that swear by dipping the freshly cut stems in alum powder (available in the spice section of the grocery) while others will submerge the entire flower in water prior to use in order to prevent wilting.

Cosmos:  Cosmos, in general, don’t have a super-long vase life, but you can prolong their beauty if you cut them at the right stage.  Cut cosmos when there is just one petal unfurling, and then let the flowers and other buds open up in the vase.

Heat loving sunflowersSunflowers:  The key to getting the longest vase life out of your sunflowers is to harvest the flowers just as the first few petals are starting to lift off of the central disk and remove all but the top few leaves.  For newbies, this can be hard because it still looks “closed” and doesn’t yet look ready to pick but if you cut them early, you can prevent insect damage plus get extended vase life.  Considered a “dirty” flower, these guys may need a little bleach in the water or cut into a bucket of water treated with a CVBn pill.

IMG_9661Celosia:  For crested celosias, commonly called “cock’s comb,” harvest when the crests are fully formed (or a little earlier is fine too) but before it starts to develop seeds. For plumed celosias, let them stretch and get feathery before picking. After cutting, be sure to strip 3/4 of the leaves off and place into cool water.

Heat tolerant flowersCerinthe: Harvest during the coolest hours of the day and then treat stems right away by dipping the bottom 2-3 inches in boiling water for 7-10 seconds and then placing them into cool water. Stems get very floppy immediately after harvest, but once hydrated, Cerinthe has a vase life of up to a week.

Rudbeckia, a heat loving flowerRudbeckia: Harvest when flowers are beginning to open. Black Eyed Susan’s are notorious for making their water murky really quickly. To combat this and extend their vase life add a few drops of bleach to the water and a 7-10 day vase life can be expected.

I’d love to know if you have any additional tips or techniques for harvesting and extending vase life for high summer blooms.  Please add your advice to the comments below.


  1. Polly on

    What do you recommend for harvesting ammi? Should I sear the end. The stems are nice and sturdy but they droop a bit around the outside of the flower head after harvest. We have beautiful Dara Ammi seeds from Johnny’s Select Seeds. Thanks!

  2. Phyllis Bruce on

    What about lantana? I read somewhere that rudbekia does not do well placed in oasis. I recently tried lantana for a church arrangement and used oasis. The foliage was perky when I made the arrangement, but had drooped alarmingly the next morning. The lantana I picked the same day, and placed in a clear vase is still looking good almost two weeks later! Flowers have faded but the foliage is just fine.

  3. Jessica Gale on

    Hi again,
    Wondered if you’d be able to share what that small rudbeckia variety is?

  4. Jill on

    Maureen, I could be wrong but I think the small yellow flower in the sunflower arrangement is tanacetum vulgare, or common tansy. It grows wild here but I use it in arrangements, has a pretty long vase life, too.

    I would be interested in more information on conditioning dahlias, as well – maybe there is more in a dahlia-specific post? Will look.

  5. Maureen on

    What cultivar is the tiny yellow flower in the sunflower arrangement? I’ve been searching high and low for rudbeckia (or similar) that produces small, spray-like flowers but haven’t had much luck. Thank you!

  6. Nicole on

    Thanks so much! Would love to know when to cut Ammi Majus?!! Don’t seem to get it wright.. Thanks!

  7. Carolyn on

    I’m a newbie Farmer Florist and it seems every time I’m scratching my head about something in pops an email from your blog with the answer. I’m forever grateful for all your words of wisdom.

  8. Lorrie on

    Hi Erin,

    Thanks so much for this post. I am an aspiring very small scale flower farmer, hoping to be in full swing next spring. I’ve been experimenting with ways to make the flowers last longer, preferably without a preservative. Just yesterday morning I harvested buddleia and hydrangea directly into hot water, and then found your post. What a treat!

    I do have a question:
    Once I’ve harvested into hot water, split the stems, and let the water come to room temp., what next? Haha! I mean, if I need to cut the stems for an arrangement (which, I will), can they go directly into cold water (since not all the flowers in the bunch want hot water)?

    Thanks for any help you can offer. I just recently found your blog and have been so blessed and inspired by it.


  9. Stefanie H. on

    O.k. Any advice for aphids!!!! I get them every year on Sunflowers. Been harvesting and haven’t noticed till now. They are terribly infested!

  10. Drea on

    Susan, if you search CVB pills on the Crysal website, I think you’ll find what you need to know! I know you didn’t ask me, but just thot I’d throw that out! I also would like to hear what you have to say on dahlias, Erin!! We’ve been trying some things, such as recutting under water, then Quick Dip them, or put in very hot water for awhile. Changing the water every day and such.. But would love to hear what a pro does!! :) Thanks as always, for your helpful info!

  11. Naly on

    Thanks for the info!! You’re so nice to share your experience and tips!!

  12. LindaQ on

    I am finding that celosia and rudbeckia do better if they are cut in the evening otherwise they droop. Rudbeckias also seem to be the first flower to wilt in bouquets that we bring to our farmer’s market…I will have to see if removing all of the leaves from the stems will help. Keep the ideas and advice coming!

  13. Gail Wynne on

    I have often referred to an old book “A Garden for Cutting” by Margaret Parke where I learned to sear the ends of hydrangeas and dahlias before putting them into water. It seems to work well. Glad to know about the “Dirty” flowers. Will add a little bleach along the way.

  14. Kelly H-Y on

    Awesome information … thank you! Gorgeous photos of the bouquets!

  15. Simone on

    … Thank you so much for the sharing of all your wonderful knowledge … unfortunately I can only … dream about such beautiful blooms on the country that we live on … thank you again and as always look forward to your next post …. xxx Simone

  16. amelia amish on

    thank you for all the flower tips.one thing I experimented with last year and needs further testing is vitC, the kind used for canning, got it at the grocery store. Ball brand ,fruit fresh.

  17. Mary Solbreken on

    I need any advice that you have on harvesting dahlias. I am only able to get 3 to 5 days vase life. I harvest basically when they are 3/4 open at dawn. I then place them in water and let them drink for an hour and then place in cooler at 38 degrees. I will live to know what I should try. Thanks!

  18. Maryann Nardo on

    Thanks so much for those cutting tips. I’m a designer who does not grow (yet!), but have often wondered why certain flowers I buy from our local flower farmers do not last despite giving them what I have learned to be the right care. I was hoping upon hope that you would mention DAHLIAS. They are so unpredictable, I’m afraid to use them in event work. I’ve tried every prep trick. Some last for a week and some a day or two. Any words of wisdom?

  19. Killoran Moore on

    Thank you so much for sharing this information! I share much of Kristen’s anxiety. I’m having the most difficulty with my branching sunflowers – they’re SO beautiful (rich and velvety and chocolatey), but there’ll be one head with a few closed buds a couple inches below. Sigh. This hurts my inner scrooge – I feel like the distance should be greater or they should also be open. Who knows! Maybe it’s normal!

    The only thing I’ve ever done is put a bit of sugar in the water, since that’s basically plant food. Honey also works pretty well since it’s naturally antifungal and whatnot.

  20. Floret on

    Thanks for all the great tips–keep em’ coming! Thanks also for your questions about use of CVBn pills. I just updated the post to clarify options for certified organic growers.

    • Margie Cole on

      Thanks for the clarification. Am I correct in assuming you are no longer certified organic? Part of my operation IS certified organic, and part is NOT – I’ve found it a tough call sometimes.

  21. Katie Pence on

    I found a good trick for rudbeckia. I strip off every leaf and they last and last. I also don’t get one or two that droop. It’s time consuming but works.

    • Cathy on

      How do you ‘strip off’ leaves? Pull away from the stem? Cut with scissors?

  22. Pauline on

    What a lovely post Erin, thank you so much. I always have trouble with my hydrangea, I have tried everything and now I just leave them in the garden. I have never grown zinnia’s, maybe i’ll try them next year!

  23. Kristen on

    Erin. You have no idea. I have been baby my garden all summer long. Getting up at 5:00 am in the morning just to get some extra time in the garden to weed and take care of things before having to head off to work. I’ve been impatiently waiting for something, anything, to start blooming. And finally, FINALLY, my zinnias have buds. I was so excited I may have done an Elaine Benes style happy dance right then and there. And then it hit me. I have NO IDEA what to do next. When do I cut them? How do I cut them? What if I cut to much and I kill them? UGH! And then I get your newsletter in my inbox and my anxiety level is knocked down about 100 notches. It couldn’t have been a more timely post for me. Thank you for all you do! Time to go wiggle some zinnias…. :)

  24. Jen K. on

    I love the photos! Do you have advice for dahlias and hollyhocks?

  25. Stefanie H. on

    Yes! Cutting sunflowers when you just start seeing petal folded into the disc works wonderfully. Sunflowers open perfectly every time with perfect blooms. Gonna do zinnia tip. Some of my green envy were cut too early and drooped. Thanks a bunch!!!

  26. Margie Cole on

    Forgot to add: your sunflower arrangement photo above is exquisite!

  27. Susan on

    What is a CVB pill? Thanks.

  28. Margie Cole on

    I’m very interested in your use of CVB tablets – something that I have not tried yet. I, too, am certified organic but thought they were not allowed under USDA Organic Certification.

  29. Lynn Rapp on

    You are always so generous with information making it easier and much more efficient for new farmer/florists. Thank you so very much, Erin.

  30. Anna on

    This is so helpful to a newbie like me, thank you!


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