Gardening Help Search

Plant Samples

Due to the threat of Boxwood Blight, Rose Rosette and other serious pest/disease issues, the Garden is no longer allowing plant samples to be brought in for identification or diagnosis. These problems can spread to the garden displays and severely impact our living plant collection.

Please help us protect our plants by taking clear photos of the plant you need identified or diagnosed. Images can be emailed to plantinformation@mobot.org or brought to the Plant Doctors at the Center for Home Gardening (Open every day, 9 am - 5 pm).  

For any additional questions regarding samples, please call: 314-577-9562.

Digging and Storing Dahlias, Tuberous Begonias, Cannas and Caladiums

As fall approaches with cooler temperatures and beautiful foliage displays, several pest and disease issues may also appear. Here are three common issues the home gardener may encounter as the warmer months come to a close. 

Fall webworm

Fall webworm is a moth species recognized for its distinctive webbed nests that appear at the end of tree branches. Inside the web, caterpillars (larvae) will feed on the enclosed leaves. The insect is native to North America, and is commonly found on walnut, hickory, elm, sweetgum, willow, oak, and ash tree species. The insect is considered to be more of a nuisance than a threat to the health of the tree. 

Powdery mildew

Powdery mildew is a fungus that appears as a light gray or whitish powder on leaves, stems and sometimes flowers and fruit. Warm days and cool nights in the fall encourage fungal development. The disease is considered to be unsightly rather than harmful. Leaves may turn yellow, or become disfigured, but the fungus rarely kills the plant. 

White Pine - Annual Needle Drop

Beginning mid to late September, home gardeners may notice the innermost needles of their Eastern white pine (Pinus strobus) beginning to yellow all at once. While this can be alarming, there is no cause for concern. White pines normally shed older needles around this time. 

Seasonal Gardening Tips

  • Continue watering, especially evergreens if soils are dry. 
     
  • The average first frost usually arrives about October 15th - 20th.
     
  • With the exception of tulips, spring bulbs may be planted as soon as they are available. Tulips should be kept in a cool, dark place and planted in late October. Plant spring bulbs among hostas, ferns, daylilis or ground covers. As these plants grow in the spring they will hide the dying foliage. 
     
  • Cannas and dahlias can be dug when frost nips their foliage. Allow the plants to dry under cover in an airy, frost-free place before storage.
     
  • Begin readying houseplants for winter indoors. Prune back rampant growth and protruding roots. Check for pests and treat if necessary. Houseplants should be brought indoors at least one month before the heat is normally turned on.
     
  • Nuts or seeds of woody plants usually require exposure to 3 months cold before sprouting. This may be provided by outdoor planting in fall or "stratifying" in an unsealed bag of damp peat moss placed in the refrigerator.
     
  • Cool-season lawns are best fertilized in fall. Make up to 3 applications between now and December. Do not exceed rates recommended by fertilizer manufacturer. 
     
  • Deadhead annuals and perennials as needed.
     
  • Container grown and B&B trees and shrubs can be planted. Loosen the soil in an area 2 times the diameter of the root ball before planting. Mulch well after watering.
     
  • Autumn is a good time to add manure, compost or leaf mold to garden soils for increasing organic matter content.
     
  • For best bloom later this winter, Christmas cactus, potted azaleas and kalanchoe may be left outdoors until night temperatures drop to about 40 F. 


 Learn more

Enjoy the fragrant blooms of the Ozark Witch Hazel flowering in shrub borders or wooded areas on warm sunny days.
Enjoy the fragrant blooms of the Ozark Witch Hazel flowering in shrub borders or wooded areas on warm sunny days.
Repot any root-bound house plants now before vigorous growth occurs. Choose a new container that is only 1 or 2 inches larger in diameter than the old pot.
Repot any root-bound house plants now before vigorous growth occurs. Choose a new container that is only 1 or 2 inches larger in diameter than the old pot.
Gardening Help

We have staff available to help you with your gardening questions:

  • Plant Doctors: Master Gardeners and Garden staff can answer your questions in person

    Center for Home Gardening
    Every day, 9 am - 5 pm

     
  • Horticulture Answer Service: Have your gardening questions answered over the phone

    Mon.-Fri., 9 am to 12 pm
    (314) 577-5143
     
  • Plant Information: Email your gardening questions to: 

    plantinformation@mobot.org

    We are currently experiencing a high volume of emails, 
    therefore response time may be delayed. We thank you for your patience and apologize for the inconvenience.
Bloom Time Calendar

See when plants bloom at the Garden: