Considerations for Flower Growers

We’ve outlined below the unique considerations of flower farmers interested in CNG certification. Find links to our complete standards and other details on our Produce Certification page including the list of Allowed and Prohibited Substances. General guidelines for production with CNG Produce Standards are on the second half of this page.

Hepzibah Farms' youngest farmer
Hepzibah Farms‘ youngest farmer

Tulip Bulbs: While home gardeners think of tulip bulbs as perennials, commercial flower growers treat these bulbs as annuals and replant each year. Certified Naturally Grown thus treats tulip bulbs the same way as seeds: when not available in CNG or Certified Organic form, CNG allows an exception for a farmer to use conventionally grown bulbs. This exception also applies to other cut flowers grown as annuals that are planted as bulbs, corms, tubers, and rhizomes. Examples include: ranunculus, anemone, gladiolus, dahlias, freesia, and others.

However, this stipulation is subject to change based on input from our community about untreated options. Dahlias in particular are sometimes available naturally grown from local farms. Please be in touch with any feedback you have about this exception. If you know of quality CNG or Certified Organic tulip bulb sources, let us know! We are compiling a resource list as the CNG flower marketplace expands.

Seeds, Transplants, and Perennial Stock: 

  • Generally, CNG producers must use seeds that are organically grown, whether CNG, Certified Organic, or uncertified whenever they are available. But, if a producer is unable to find the variety they need in organically grown form after checking with at least three suppliers, CNG allows an exception for a farmer to use conventionally grown seed, just as long as it is not chemically treated or genetically engineered. Pelleted seeds must not contain synthetic fungicides or germinating agents. 
  • Transplants must be grown without synthetic fertilizers, wetting agents, or pesticides, and with seeds that meet CNG standards. When purchasing transplants, sometimes it can be difficult to tell how transplants were grown. The best ways to ensure that transplants meet CNG requirements is growing them yourself if you are able, or communicating directly with the transplant grower about their practices.
  • For perennials that were started conventionally, they can be considered fully CNG after 12 months under CNG management.

Learn more about seeds, transplants, and perennial stock

Lisianthus Exception: Lisianthus (Eustoma) is popular among florists, but quite difficult to grow from seed, requiring up to sixty days to be ready to transplant, and specialized equipment to carefully monitor and control temperatures and humidity. Most direct-market flower growers, lacking the equipment, skills and/or space, must resort to buying plugs, and there are few if any suppliers of organic Lisianthus plugs. Rather than deny these flower growers CNG certification, or require them to stop growing this popular flower, we have chosen to be fully transparent about this situation and allow growers to get certified and market their bouquets as CNG even if they happen contain Lisianthus, so long as the rest of their operation as in compliance with CNG standards. We intend our certification to help move agriculture in a more sustainable direction. Preventing growers from participating due to one flower variety, when the remaining 98% of their operation meets CNG standards, just seems counterproductive.

Potting Mix: To meet CNG standards, potting mix can’t contain synthetic ingredients such as chemical fertilizers or synthetic wetting agents. Commercial potting mixes frequently contain one or both of these, so it’s important to check the ingredient list carefully if you purchase potting mix. If you are able, making your own potting mix gives you more control over the ingredients.

If you are making the switch from conventional to organic ProMix or other potting mix, the soil should behave fairly similarly. The main difference will be in rehydration. Organic soil has a difficult time reconstituting once it dries out completely, so you’ll want to just be careful not to let the soil dry out. If you’ve been using a mix that has a biofungicide, then the fungicide will kill off anything that grows as a result from over-watering or overly cold and damp conditions, so once you switch to an organic potting mix you will have to be more careful not to overwater.

Switching to an approved potting mix will mean it takes a bit more care irrigating starts in the greenhouse, but also ensure that all the flowers are grown without synthetic chemicals!

Post Harvest Floral Preservatives: CNG standards cover production practices, but not post-harvest handling. So while it’s true that most floral preservatives include synthetic ingredients, that’s not in conflict with CNG standards. Of course, we expect members to be careful and thoughtful with how they handle and discard unwanted solution. If and when a reliable organic floral preservative comes on the market, we will be sure to notify our members. 

Conventional and CNG Field Areas on the Same Farm: While most of our certified producers have their entire operation certified, there are some situations where a farmer hasn’t managed to grow certain crops according to CNG standards. It is possible to exclude some crops from certification, and have other crops get CNG certified. We just ask that it be made clear which is which during marketing, and that everything is explained clearly on the farm’s public profile on the CNG website.


Below are some more general CNG guidelines:

Soil Fertility: To manage fertility on their farm, CNG farmers use management practices like cover crops and crop rotations, and organic amendments such as compost, manure, fish emulsion, soybean meal, feather and bone meal, and unprocessed minerals. Synthetic fertilizers are not allowed.

Weeds, Pests and Plant Disease: CNG encourages mechanical and cultural methods as the first line of defense against weeds, pests, and diseases. When those methods don’t solve the issue, most botanical and biological controls, such as ladybugs, BT, neem, or kayolin clay, are also allowed. (Rotenone is a notable exception; though it is an unprocessed botanical, it has been linked to Parkinson’s Disease and is not allowed). As a general rule, most OMRI-approved products meet CNG standards. No synthetic herbicides, pesticides, or fungicides are allowed.

Buffers: It is important for CNG farmers to have an adequate buffer to protect their fields from potential sources of contamination. The appropriate size of the buffer depends on the context, including factors like prevailing wind patterns, the elevation and slope of the land, and what the neighboring land uses are. Typically, we look for a minimum distance of 20 feet to crops like a fertilized hayfield, field corn and soybeans, while a buffer of 50 feet is required for crops such as sweet corn. A buffer may need to be somewhat larger if for example the growing area is located downhill or downwind, or it may need to be quite a bit larger if you are located next to crops that are sprayed aerially.

Paperpot Transplanters and Biofilm: We consider the paper chain pots to be compostable, in the same category as paper mulches. Learn more about our stance on paper pot transplanters and biofilm.  

If you still have questions about how your practices align after reviewing this page, please reach out to suzannah@naturallygrown.org