We thank Mandy and Steve O'Shea of 3 Porch Farm for sharing this guide to planting and caring for your Heirloom Chrysanthemums. 


Congratulations! We are so excited to share your new plants with you! We hope these will be a beautiful addition to your farm or garden. Here’s some key tips on how to care for your new additions and best practices that all farmers can use for any plants received from any other grower/supplier going forward.

~ Mandy and Steve O'Shea, 3 Porch Farm

Learn more about 3 Porch Farm's commitment to sustainability here. 


Upon arrival, keep new plants separated until you’re able to inspect and treat them. All farms have some pest and disease pressure but pathogens and intensity vary based on crop, farm, and location. You don’t want to contaminate any of your existing plants with something new. Keeping them separated until you’re able to evaluate their health will prevent this. We have no issue with Chrysanthemum White Rust on our farm. In over a decade of growing mums, we’ve never dealt with this disease. However, like every organic greenhouse grower, we do deal with aphids and fungus gnats. They are unavoidable pests and are just a part of growing organically indoors.

Controlling populations with the most eco friendly yet effective approach possible is the best reality we or any grower can achieve and we provide detailed solutions below for your reference.

That said, we aim to provide you with sanitized plants and we do treat them with organic pesticides and fungicides the day before shipping to give you a clean slate, but since we don’t nuke with synthetics, it’s possible an aphid will slip by.


Repot your plants. We fertilize our seedlings regularly to ensure your plants are strong and healthy. Upon arrival, they will be ready for more food and want room to grow. Repotting with a good soil mix, organic fertilizer, and compost will ensure they’re off to a great start in their new home.

Check For Pest and Disease

Inspect all new plants for pests and disease. Knowing what to look for will determine what you should treat with. We will help you identify those below.


Aphids are the most common insect you’re likely to encounter, especially in chrysanthemums. They are slow moving, soft bodied, and come in many colors including green, brown, and black. They like to live in new tender growth and the underside of leaves. Look in these areas on your plant while inspecting.

They are easily managed using organic products and regular treatment. Aphids can become a problem if left untreated. They multiply quickly in greenhouses and grow rooms.

If you see aphids on your plants, begin by knocking them off by spraying with a hose.

To learn more about Aphids, Click Here.

What 3 Porch Uses:

  • Pyganic
  • Venerate
  • Insecticidal Soap
  • Azadirachtin

It is important to rotate your products so your insect populations won’t build up resistance.

Fungus Gnats

Fungus Gnats are small dark flies that enjoy moist areas. They are weak flyers and lay eggs in wet media. While common, chronically wet conditions in a greenhouse or soil can allow populations to establish. Large populations will affect growth, as the larvae will steal nutrients from the plant's roots.

The best treatment for fungus gnats is letting the soil dry in between waterings but there are a few predatory insects, like nematodes, and organic products, like BTI, that can be effective management tools.

To learn more about Fungus Gnats, Click Here.

What 3 Porches uses:

  • BTI, such as Gnatrol or Aquabac
  • Stratiolaelaps scimitus (predatory mite)  
  • Insecticidal soap
  • Beneficial nematodes
Powdery Mildew

Powdery mildew is a white mildew that grows on the leaves and stems of a plant. It looks like flour was spilled on the plant and can be wiped off with touch.

It is common on dahlias and chrysanthemums. It will begin in dense foliage during humid weather.

The best way to prevent powdery mildew is to have plenty of airflow and ventilation. While powdery spores are all around us, they cannot establish unless they have the right conditions. Powdery mildew is rarely life threatening to plants but can slow growth and production substantially if left untreated.

Clean plants regularly by removing old growth and dense foliage. This allows airflow into your plants.

To learn more about Powdery Mildew, Click Here.

What 3 Porch Uses:

  • Oxidate
  • Serenade
  • Bi-Carbonate

Rotate these sprays to not build up resistance. For heavy pressure, treat with oxidate and follow up with serenade. Target the foliage when treating.


Rot is a general term for root and stem infections in plants. There are many pathogens that cause similar behavior such as fusarium, botrytis, and pythium.

While they have similar symptoms, it is nearly impossible to know without testing the infected plant what specific pathogen you have. Regardless, the treatment for plant diseases is generally the same.

Cultural methods like good cleaning and sanitation are important. Do not handle new or infected plants and then handle your existing ones.

Remove all plant debris from grow areas.

Clean tools like shears, trays, hands, and gloves after working with new or
infected plants.

To learn more about disease identification, Click Here.

What 3 porch Uses:

  • Oxidate
  • Serenade
  • Bi-Carbonate
  • For soil borne disease, heavily water the soil with the fungicide. For foliar diseases, spray the leaves.


When your plants arrive, isolate them and thoroughly look over them. Check for these major concerns. We recommend treating with an organic fungicide and pesticide from the recommended list even if no issues are present. This is something we always do when receiving new plants! Reminder to always follow the label for application rates and PPE. After evaluating for several days, you can determine if they are healthy enough to join your other plants. Happy Growing!

Planting Tips

Once plants have adjusted to the new climate and quarantined, you can plant them in a sunny part of the garden or in tunnels for Fall flower production. Mums should be spaced 1 to 2 feet apart depending on the size of the plant when planting out. Plants can be cut back as late as early July to encourage bushier plants. We recommend cutting back multiple times to increase stem count. Most varieties do get tall even after pinching so we highly recommend adding horticulture netting on top of the plants to help protect the stems from bending or breaking.

Our Spray Approach

We will spray weekly with a mix of insecticidal soap, Venerate, Serenade, and Carb-O-Nator. Sometimes we’ll rotate out soap for azadirachtin, or Grow Safe. This approach keeps aphids and powdery mildew in check.

Here is the critical part....right before flowers start to bloom, we’ll do a very intensive spray with Pyganic to kill every single aphid possible. If you spray with Pyganic every week, aphids will develop a resistance, so we reserve this tool for one heavy spray right before bloom. This gives us almost zero aphids on our bouquets. After that heavy Pyganic spray, we rotate back to the original mix for the next few weeks until harvests are finished. Pyganic will ruin flower petals. Azadirachtin will too. Our earlier mentioned mix is safe to use on open flowers. Avoid spraying anything in full sun on hot days if possible.


Harvest when flowers are mostly open. Mums do not continue to open much after harvesting. Protect blooming plants from frost in the Fall as they are usually in full flower during Frost conditions.


In order to overwinter these varieties, plants will need to be protected from deep freezes. We suggest digging them up and storing them in a pot in a greenhouse, garage, or other protected space.