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.

September Pests & Problems

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

  • 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. 
     
  • 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. 
     
  • Divide peonies now. Replant in a sunny site and avoid planting deeply.
     
  • 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.
     
  • Fall webworms begin nest building near the ends of branches of infested trees. Prune off webs. Spray with Bt if defoliation becomes severe. 
     
  • Evergreens can be planted or transplanted now to ensure good rooting before winter arrives. Water both the plant and the planting site several days before moving. 
     
  • Paw paws ripen in the woods now.
     
  • Broccoli, cabbage and cauliflower transplants should be set out now for the fall garden. Sow seeds of beans, beets, spinach and turnips now for the fall. Spinach may germinate better if seeds are refrigerated for one week before planting. 
     
  • Autumn is a good time to add manure, compost or leaf mold to garden soils for increasing organic matter content.


 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.
Bloom Time Calendar

See when plants bloom at the Garden:

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.