Expert October Gardening Tips from a Harris County Master Gardener
By Karen Shook, Harris County Master Gardener
October is a prime time for planting woody ornamentals, container grown roses, shrubs, trees, vines, many bulbs, groundcovers, and many types of annuals and perennials.
Remember the Chinese proverb “The best time to plant a tree was twenty years ago. The second-best time is now”.
Keep beds mulched to discourage weeds. Watch for and treat pests before they settle in for the winter.
August 2023 set new 25-year records for highest average temperature and lowest rainfall. I have to admit that when it rained last week, I went out and played in the rain to celebrate. Forecasts suggest temperatures will continue slightly higher than average.
Perennials and Ornamental Grasses
- In September, you probably divided daylilies, calla lilies and irises. If not, divide those in October along with other spring blooming perennials (Shasta daisy, gaillardia, cannas). Move perennials you want in a different spot. Give them a good soaking after moving.
- Plant new perennials and fertilize the new plantings with 1/2 strength soluble fertilizer. Marigolds, chrysanthemums or perhaps Texas Superstar Marimum (Tagetes erecta) are nice fall choices.
- Spread wildflower seeds. Gently rake them into the soil.
- Plant cool weather annuals like snapdragons, pinks, poppies, calendula, stock, dianthus, alyssum. There seem to be many opinions on when to plant pansies and violas. Some say to plant in September, some say October, others say wait until November. Personally, I am going for late October.
- Biennials like poppies, larkspur, bluebonnet seeded now will germinate, spend the winter as a small plant, then in spring grow and bloom. Mix fertilizer into soil before planting.
- Lightly fertilize annual beds to give warm season annuals a boost and get cool season annuals off to a good start.
- Plant bulbs (except tulip and hyacinth which are in your refrigerator waiting for December). A general guide is to plant at depth three times the diameter of the bulb (so a two inch diameter bulb would be planted at a depth of six inches). Mulch and water when you plant.
- Divide spring to early summer blooming bulbs (daffodils, paperwhites, amaryllis, columbine, purple coneflower, etc.).
- In late October dig up and store caladium bulbs for planting next spring.
- Continue regular fungicide spraying, although you may be able to reduce frequency as we get cooler, drier weather.
- No fertilizer should be used after early October (Guidance is to stop two months before first frost which in Zone 9 is typically November 25 to December 13).
- Fertilize any new shrubs planted in October. Do not fertilize established shrubs.
- Watch for and treat pest problems. Azalea lacebugs, camellia tea scale, and caterpillar activity are some things to watch for.
- Spread wildflower seeds. Gently rake them into the soil. mConsider adding columbines. Two native species of columbines are Red (Aquilegia canadensis) and Hinckley's (Aquilegia chrysantha var hinckleyana).
- Watch for brown patch (circular brown areas with yellowing grass at the outer edge of the circle). Milder temperatures and rainy weather encourage brown patch.
- If you didn’t winterize in September, it is a task for early October. Pre-emergent herbicides can be applied in October to discourage cool season weeds. Check the label to see what soil temperature is needed for best performance.
Edibles (vegetables, herbs, berries, fruits)
- October is a good month for planting perennial herbs (thyme, marjoram, oregano, rue, etc.)
- See the following link for recommended planting times: Harris County Vegetable Planting Guide
About Urban Dirt
Each month, Harris County Master Gardeners publishes an informative, resourceful newsletter entitled "Urban Dirt". This article was derived from the October 2023 edition. To read the October 2023 edition of this newsletter, click the button below.