With the first fall frost, tomato, basil and pepper plants shrivel and turn mushy. Most perennials have expended their energy for the season and are brown and dry. The garden can be a downright melancholy place, especially for the avid gardener. By carefully incorporating annuals into your gardening repertoire, though, you can extend the season by several weeks.
Many annuals are frost-tolerant; some tolerate a bit of frost, while others bloom cheerfully through a layer of snow and ice. Pansies are probably the most well-known frost-tolerant annual, and they do look beautiful paired with flowering kale, but there are many other options that you may not have explored.
Frost Hardy Annual Varieties
Consider the following frost hardy annuals for your garden and planters:
- Bachelor’s button
- Black-eyed Susan
- Sweet pea
- California poppy
- Sweet alyssum
- Bells of Ireland
Plant these annuals in the garden in the spring and they’ll continue blooming until the first hard frost, or even after, depending on the variety and care. You can buy most of these plants at a well-stocked nursery, but starting annuals from seed is a fairly easy task. When you plant annuals from seed you save money, have a greater variety of plants to choose from and have direct control over the health of the plants.
Starting Annuals from Seed Outdoors
Most seeds can be sown directly in the ground, and some, such as poppies and sweet peas, don’t transplant well and are best sown this way. To sow seeds directly in the garden, remove weeds and debris in the spring. Spread 1 to 2 inches of compost or manure over the soil. Till the soil and rake it smooth so the surface is very fine. A hard, crusty surface may inhibit germination. Place the seeds 6-12 inches apart and sprinkle them lightly with soil. Most annual seeds are very small and don’t need to be planted deeply, but consult the seed packet directions for planting depth. Water the soil with a light mist sprinkler as needed, to keep it evenly moist.
Sowing annual seeds among perennial plants is a bit tricky, especially if the perennial plants aren’t visible in early spring. Mark the location of perennials with a craft stick in the fall so you know exactly where they are. Sow annual seeds 2 to 4 inches apart between the perennials. Make sure to plant tall annuals at the back of the garden and smaller ones at the front. Select annuals that complement the color scheme of your existing perennials. As the annuals grow, thin them out if necessary.
Starting Annual Seeds Indoors
Some annual seeds, such as snapdragon, phlox and pansy, germinate well in cold soils, but most seeds germinate better when soil temperatures are at least 60 degrees Fahrenheit. Sow these seeds directly in the garden after the soil has warmed up, or start them indoors for a head start.
To start annuals indoors, fill a seed starting tray with a high-quality perlite or vermiculite starting mix. Do not use ordinary garden soil, which is too heavy and may contain pathogens. Poke holes in the starting mix with a pencil or a chopstick and drop the seeds in the holes, spacing them 3 inches apart. Mist the starting mix with a spray bottle filled with water to moisten it. You want it to be evenly moist, but not soggy. Cover the seed tray with a sheet of plastic wrap, which will create a greenhouse effect, conserving moisture and heat. Set the seed tray in a warm location, such as the top of your refrigerator. Check it every day or two and water as needed.
Once the seeds germinate, remove the plastic wrap. Move the seed tray to a sunny location and water the young plants as needed. When the plants stand 2 inches high, thin them to 4 inches apart. Move the plants outdoors when they stand 4 inches high.
Fall Annual Maintenance
Because annuals produce flowers prolifically for a short period of time, they take a bit more maintenance than perennials. Fertilize them every 3 to 4 weeks with a water-soluble fertilizer; otherwise, they may not bloom through fall. Another important task is to deadhead annuals. Deadhead, or remove faded flowers, to promote more blooms. Impatiens and sunflowers do not need deadheading, but most annuals will benefit from this practice.
Want to learn more about extending the gardening season with fall annuals?
Winter Annuals for Fall Color [PDF] – University of Florida Extension
Cold Tolerant Annuals [PDF] – University of Minnesota Extension
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