September Horticulture Hints

Some mornings I feel a hint of coolness in the air. Amiable Spouse says it’s my imagination, but I know better. Gardeners get energized and seize these days to plan, plant, transplant, and prepare. Every one of us wishes we had an extra gardener to accomplish all the tasks that need to be done during fall’s favorable weather. It’s a busy time.

Gardening Tasks

Order cool-weather vegetable and flower seeds so that you will be ready to plant when the weather moderates.

• Flower seeds to order include reliable plants like bachelor’s button, sweet pea, calendula, nigella, larkspur, candytuft, and alyssum.
• Vegetable seeds to order now include greens such as mustard, spinach, collards, turnip, and kale. Prepare a bit of ground for some carrots, lettuces, radishes, and onions to add zest to winter salads.  Plan for some variety with vegetables by including Brussels sprouts, cabbage, broccoli, and cauliflower.
• In the herb garden or in containers, plant dill, fennel, sage, thyme, and rosemary.

Some annuals that have worked hard all summer may give one last show if cut back and fertilized. If they are obviously spent, however, now is a good time to pull them up and renew the soil by adding compost or other organic matter. In a few weeks the seeds that you ordered will be ready to plant.

Divide amaryllises if they bloomed poorly last spring. Carefully dig and separate the bulbs. Add organic matter to the soil in the entire bed. Dig holes eight to ten inches apart and sprinkle a tablespoon of slow-release bulb food into each planting hole. Mix the fertilizer with existing soil, and replant in the prepared holes. Leave the foliage intact—it will die down naturally. Daylilies, crinums, Easter lilies, irises, and other spring- and summer-blooming perennials and bulbs may also benefit from separation or division.

September is the last call for adding fertilizer to ornamental shrubs. Pruning should not be attempted at this time of year. Fertilizing and pruning stimulate new growth which may not have time to harden off before winter. Early in the month is also the latest time that lawns should be fertilized.

Use fallen pine needles for mulching perennial and shrub beds. Start expecting some of our deciduous trees to show some color and loose their leaves. Use these leaves for mulching or for composting.

Caladiums will begin to die down this month. Dig them and place in a shady location to dry out. Store until next spring in a place where the temperature stays above freezing.

Start moving houseplants closer to the house. Check for pests and treat if necessary. Fertilize and let them have one last fling before they are moved back inside.

Order spring flowering bulbs now. Choose early-blooming varieties of narcissus, hyacinths, and tulips. When they arrive, place them in the refrigerator for 6 – 8 weeks. Be sure to avoid placing them near fruits which give off gases that retard bloom formation.

Fall fertilization should be completed by the end of this month.

Color in the Garden

Fall is when some of our most beautiful gingers bloom. White butterfly ginger and Kahili ginger sport spectacular bracts on the ends of their stems from which orchid-like flowers bloom. The “cones” of pine cone ginger turn bright red, and the hidden gingers hide beautiful bracts among their banana-like leaves. Many species of gingers do well in gardens in our area, and now is a good time to add them to your garden.

Many perennials are now at their best.

• Summer phlox continues to bloom if spent blossoms are cut off as they fade. Gaura is putting on a flush of flowers after last month’s pruning.
• Blue plumbago and society garlic, which have been blooming all summer, continue unabated.
• Butterfly weed, cigar plant, and ‘Purple Knight’ Alternanthera decorate the border.
• Other perennials giving seasonal color include Mexican bush sage, Philippine violet, cigar plant, firespike, chrysanthemum, goldenrod, forsythia sage, and Mexican mint marigold.

If your garden suffered from the late summer blahs, consider adding some of these flowers to your border. Now is a perfect time to plant them.

Plant, Plant, Plant

September is an excellent time to plant woody ornamentals, including trees, shrubs, vines, and groundcovers. Mild winters allow the roots to grow and become established before the heat of summer sets in.

Some annuals that have worked hard all summer may give one last show if cut back and fertilized. If they are obviously spent, however, now is a good time to pull them up and renew the soil by adding compost or other organic matter. In a few weeks the seeds that you ordered will be ready to plant.