Weekly Express-News Article

By Calvin R. Finch, PhD, SAWS Water Resources Director, and Horticulturist

Saturday, October 4, 2008 

“Autumn Blooms”

             Garden mums are as indicative of the autumn as college football.  Their bloom period is relatively short, three – five weeks, but they make a great show during that period and, of course, they are perennials so if you plant them in the garden in full sun, they will bloom for you year after year.  There are many colors from white through yellow, rust, lavender, and violet.

 

            The most popular garden mums are the mounding form.  They grow to three feet in diameter and just over two feet tall and will be covered with blooms in the fall.  Here in San Antonio, we usually also get a good spring flush of blooms.  We used to recommend that they be pruned off in order to maximize the fall bloom, but I am not sure it is necessary.  Enjoy the blooms both spring and autumn.

 

            Purchase your garden mums now.  Depending on how fast you want the impact, select open, partially open or closed buds.  They can be planted directly into the garden if you want to take advantage of their perennial nature, but they can also be used for short-term impact.  For a wedding, Halloween Party, Thanksgiving, get together or any other event, garden mums can be used for instant temporary color.  Place their plastic container in a planter or decorative container.  It even works to place a mass of mums on the ground surrounding the patio with the space between the pots filled with bark mulch to the depth of the pot.

 

            In the garden, water garden mums every week during the summer unless it rains, pinch the growing tips every month and prune to maintain a uniform mound.  After early August, let them grow and bloom without further pruning.  Insects and diseases are usually not a problem.  Fertilize with a quarter cup of slow release lawn fertilizer in March and then at your last pruning in late summer.

 

Fall asters are also called Michaelmas daisies or Frikartii asters.  They have a similar pattern of bloom as garden mums.  They are spectacular for a short period in the autumn.  In the nursery they look a lot like garden mums, disciplined mounds covered with blooms.  The blooms are blue purple. 

 

            The plants in the nurseries have been treated with growth hormone to produce the small mound.  In your garden after the hormone wears off (next year), the fall aster will grow to a mound that can be six feet in diameter and three feet tall.  Use them as a focal point for the fall landscape in full sun. 

 

            Fall asters are good xeriscape plants, use them in a hot dry spot like at the corner of the driveway and sidewalk or near the corner of the lot.  The foliage is less showy than the garden mums, a gray green, so the plant is  inconspicuous until it blooms.  Grow it the same way as a garden mum.  Keep it pruned to a mound about 18 inches in the center until mid-August and then turn it loose to grow to full height and width, and to form the flower buds.  Fall aster is a favorite butterfly plant during its short bloom period.  Fertilize in the fall when the pruning ends.  The plant should only need water once/month if it does not rain.  

 

            There are many petunia varieties to select from including fully doubles and deep colored multi-flowers.  There are reds, pinks, salmon, whites, purples, and lavenders.

 

            My favorite petunias, however, are the hardy selections such as VIP, Laura Bush, and Wave.  The colors and flower shape are less showy, but they are longer lasting with capability to survive cool weather and heat.  VIP is the lavender parent petunia.  It has small, but numerous flowers that climb and can survive and reseed over a long period.  Some gardeners cut them back several times per year to keep the foliage attractive and to renew the stems.  Laura Bush is a sterile petunia one generation removed from VIP.  The flowers are larger and the flower color includes more pink, but it is nearly as tough as VIP.  Wave is available in pink and lavender.  The blooms are very large and the color is superior. I especially like the pink.  If the summer is mild, Wave may have a few blooms all season, but if it is hot and dry, many of the plants survive and perk up to have a long fall, winter, and spring bloom period.