Our gardens have reached their peak and are almost more beautiful than they were all summer. Sadly, this always occurs just before a killing frost. The median first frost in Cass County is September 16-30, with the average date on the 24th.
It is time now to clean the houseplants that have been vacationing outside and to bring them indoors. Many of our houseplants are tropical and do not fare well when the temperature drops below 50 degrees. It is best to bring them in before we have to turn on the heat so the plants have time to acclimatize. I do like to leave Christmas cacti outdoors in a protected spot until just before a hard frost. This encourages them to set buds.
This summer I have had a big problem with mealybugs on some of my houseplants and I am going to have to be extra diligent in washing them off. I will first use a strong spray of water from the hose and then spray well with insecticidal soap (Safers). Mealybug females, which are what we see, are long oval, segmented insects. They are covered by white cottony tufts. The males are minute, two-winged insects that are rarely seen. The female and nymphs feed on plant sap and the juice of leaves and fruit. I will have to isolate the infected plants from my other houseplants until I have this problem under control. Aphids and spider mites are also apt to hitch a ride with houseplants and annuals that we bring indoors.
Extend the life of your annuals through light frosts by covering them overnight with blankets or row covers and removing the blankets in the morning. Often we have a few frosty nights and then it warms up for a week or two. Move your container plants in and out of the garage or shed and be sure to keep them watered. You may wish to replace some tired container plants with ornamental kale or cabbage, which can keep looking good until November. Winter pansies are available now, along with budded mums and asters. Fall planted garden mums do not usually survive the winter, however, I have had some potted mums live after storing them in my garage.
If there are some annuals, such as coleus, geranium, fuchsia, fibrous begonia and impatiens that you hate to part with take 4"-6" cuttings now. They take up less space than the whole potted plant. Put the cuttings in moist vermiculite, perlite or well-drained potting mix and they will usually root in two weeks. Plant the rooted cuttings in small pots of good potting soil.
You can still dig and divide iris this month, but the later you plant the more risk of winterkill. Wait to dig peonies until the tops have been killed by frost. September is a good time to add new perennials and shrubs to your landscape. They will appreciate the still warm soil and the usually cool air temperature. Don't transplant shrubs or trees until their leaves have fallen and they are dormant.
Because of the cooler than average summer, perennial and annual flowers have thrived. I'm sure that all gardeners have something that they are especially proud of. I have a white cosmos 'Sonata' that is especially beautiful. However, I realized that I prefer the old standby 'Victoria' salvia (an annual) over the newer variety that I planted. 'Victoria's' height and striking color stands out so well among other flowers. Another annual that was exceptional for me was the double white petunia also called 'Sonata.' I have been snapping pictures of my roses all season. The hardy 'Hope for Humanity' has been outstanding. It has abundant, reoccurring clusters of deep red roses and mine has grown to over six feet tall. At this time of year, I have stopped clipping off the spent rose blooms. I will allow them to develop rose hips and this signals the plants to slow down and harden off for winter.
Take pictures of your gardens so that you can enjoy looking at them in winter and so that you can remember what you loved so that you can plant it again