How to preserve zinnia seeds

In this brief guide, we are going to answer the question “how to preserve zinnia seeds”, and discuss in-depth the correct method to harvest and store zinnia seeds.

How to preserve zinnia seeds 

The World Health Organization highlighted that more than half of the world’s population (80%) rely on the application of medicinal plants for various health care measures. Flowers are the reproductive structure of flowering plants (also known as bloom or blossom) that have been in use by mankind for various food and pharmaceutical applications and thus otherwise also referred to as edible flowers (1).

Zinnia seeds must be harvested and air-dried for preservation. After drying they can be preserved in paper bags or envelopes until needed.

Zinnias are colourful flowers that are also edible (5). Zinnia petals have a slightly bitter flavour and they can be added to dishes such as garden salads or desserts. Zinnia petals both fresh and dried, can be used to brew floral teas by adding them to boiling water.

Zinnias are annual plants. They will grow, bloom and flower in one season and will not return in the next season. So the seeds must be preserved and newly planted in the next season. Zinnia (Zinnia elegans L.) is a most important flowering plant, belonging to the Asteraceae Compositae family. Its origin is Mexico and Central America (2).

How to harvest and clean zinnia seeds for preservation

Zinnia seeds must be harvested from completely dry flowers. Also, the flowers must be allowed to mature and dry in the plant. So cutting young flowers and then drying them will not produce viable seeds.

Relative humidity and temperature of the storage environment are the most important factors affecting maintenance of seed quality during the storage period. Of these two factors, relative humidity is most important because of its direct relation to seed moisture content (3). Commercial seed storage is conducted at 12-15°C (53-60°F) temperatures with 40-60% relative humidity for medium-term storage (12-36 months). Seed moisture content for small-seeded species is supposed to be 5-7% for an ideal storage environment (2).

To harvest and zinnia seeds:

  • Cut off the completely dry zinnia flowers from the plants.
  • Remove the seeds from the flower heads. This can be done by gently pulling apart or rubbing the seed head of the dried flowers. 
  • Separate the seeds from the chaff. Chaff is the scaly outer covering of the seeds that protect them during growth. You can spread the seeds on a tray and move around the seeds to identify and discard the chaff.
  • Discard the petals and the chaff.
  • Spread the zinnia seeds on a clean, dry tray.
  • Dry the zinnia seeds. The best method to dry zinnia seeds is by air drying. Place the tray with zinnia seeds uncovered in a well-ventilated area. Make sure that the seeds are completely dry. Any moisture will cause mould growth and spoilage. 

Do not use heat-based drying methods such as oven or dehydrator drying as heat may make the zinnia seeds unviable. A 10-year storage life can be achieved by drying seed to less than 8% moisture. To do so, dry seed at 100°F for six hours. Obtain this temperature by spreading the seed out in direct sunlight. However, because sunlight is harsh and easily can exceed this temperature, drying in the shade is better (4).

  • After drying, place the zinnia seeds in small paper bags envelopes. Paper bags and envelopes allow air circulation and will keep the zinnia seeds dry.
  • Label the envelopes and store them in a cool, dry place away from direct sunlight.

How to store zinnia seeds

Iit is of paramount importance that seed moisture content after harvest be rapidly and safely reduced to 12% or less for the cereals and 11% or less for most other kinds of seed. Moreover, the storability of seed is adversely affected by mechanical injury to seed, insect damage and infestations and plant diseases that infect seed (3).

Dried zinnia seeds can be safely stored for 3 – 5 years. Transfer the dried paper bags or envelopes and store them in a cool dark place until you are ready to use them. The storage environment is conditioned by drying the seed to a low moisture content and packaging in moisture vapor proof containers or by air cooling and/or dehumidification. Cold and dry conditions will maintain the quality of seed for many years in storage. For three to five years storage, conditions of l0 °C and 45% rh are satisfactory for most kinds of seed. Successful storage for five- fifteen years can be achieved under conditions of 0 o to 5 oc and 30-40% rh (3). 

  • Make sure that the paper bags or envelopes are labeled so that they are not confused with other seeds.
  • Store the seeds in a place where they are not accessible to rodents and insects.
  • You can also store the zinnia seeds in a refrigerator. Place the zinnia seeds in a ziplock bag or an airtight container before refrigerating. This will protect the seeds from moisture.

How to use preserved zinnia seeds

Zinnia seeds do store well. However, they might not be viable after a few years. So it is a good idea to check if the stored zinnia seeds are still viable before planting them. A water test can determine the viability of zinnia seeds

To check if zinnia seeds are viable :

  • Put the zinnia seeds into a container filled with water.
  • Allow the seeds to sit for about 15 minutes.
  • After 15 minutes, the variable seeds would sink to the bottom. The seeds floating on the top are not viable and they would not sprout if planted.

Tips for harvesting zinnia seeds for preservation

  • Always harvest seeds from open-pollinated plants. Seeds from open-pollinated plants will grow up with the same characteristics as the parent plant. To make sure that the flowers are open-pollinated, tie a bag or cage around the flowers or plant flowers of the same variety in one bed. This will prevent cross-pollination.
  • Preserve only mature zinnia seeds. Only mature seeds are viable and will germinate. The mature seeds will be full and not bend. Any bendable seeds are not mature and must be discarded.
  • Always harvest seeds from healthy plants. Certain diseases such as powdery mildew may spread to seeds and future crops.
  • Harvest seeds from completely dry flowers. A completely dry flower will be brown with dry and crisp petals. Seeds harvested from young flowers will not germinate. Seeds harvested from flowered cut before drying out will not germinate as well.
  • Avoid watering the flowers before harvesting. This will add moisture to the seeds and they will take longer to dry out.
  • If you are harvesting seeds from many varieties of zinnia, make sure to label the storage bags clearly to avoid a mixup.

Conclusion

In this brief guide, we answered the question “how to preserve zinnia seeds” and discussed the method to harvest, dry and store zinnia seeds. We also discussed how to check the viability of zinnia seeds.

If you have any questions or comments, please let us know.

References

  1. Purohit, Soumya Ranjan, et al. A review on nutritional, bioactive, toxicological properties and preservation of edible flowers. Future Foods, 2021, 4, 100078. 
  2. Demir, İbrahim, Zeynep Gökdaş, and Nazlı İlke Eken Türer. Changes in seed germination during storage of flower seeds: Species differences. Uluslararası Tarım ve Yaban Hayatı Bilimleri Dergisi, 2020, 6, 416-422.
  3. Delouche, James C., et al. Storage of seed in sub-tropical and tropical regions. 2021. Mississippi State University  
  4. Ells, James E., Louis N. Bass, and D. Whiting. Storing vegetable and flower seeds. Colorado State University Cooperative Extension, 2003.
  5. Abbott, Elise. Chemical Free Edible Flowers. 2019. Murray State University