The first spring I worked on a flower farm, I was amazed at the height of the flower stalks. Snapdragons hit my chin, and the campanula stalks were waist-high. How did these flowers grow so tall?
After talking to more experienced growers, I learned that planting the flowers in the fall or winter helped them obtain their impressive height. Earlier planting times gave them time to develop strong root systems and foliage in cooler weather. When longer and warmer days arrived, they sent up tall flower stalks perfect for cutting and arranging.
Since these flowers will be outdoors during the winter, you’ll want to choose cold-hardy varieties and pay attention to your hardiness zone. High tunnels and row covers provide some protection from low temperatures, but overwintering is not always possible in colder climates. I’ve included information about each plant’s cold hardiness to determine if fall planting will work for you.
Helpful Tips for Fall Sowing and Overwintering
Whether you’re growing outside under row cover or in a protected tunnel, aim to keep the soil on the dry side.
Before I dive into the specific flowers that benefit from overwintering, I want to introduce you to a few tips. These will help keep your crops healthy and increase the chances you’ll have beautiful flowers to harvest when spring arrives.
- Plant early enough. When day length drops below ten hours, plants put on little growth. Therefore, aim to plant your seedlings at least one month before the day length reaches ten hours. This will give them time to develop strong root systems before dark, cold days arrive.
- Don’t overwater. No matter if you’re growing outside under row cover or in a protected tunnel, aim to keep the soil on the dry side. Wet soil encourages the development of multiple fungal diseases that can lead to the plant’s demise.
- Be aware of airflow. Unless you live in a climate that rarely drops below freezing, you’ll likely need to cover your beds with row cover. However, don’t leave the covers on for the entire winter. Removing the covers on warm, sunny days allows for airflow and helps with disease prevention.
Snapdragons
Pinching the seedlings when they’re young helps encourage branching and leads to a greater number of flower stalks.
One of the best ways to grow snapdragons for cutting flowers is to sow the seeds in the early fall and transplant them into your garden when they’re about a month old.
Although the plants are extremely cold-hardy, you want to sow the seeds a few weeks before the first frost. This gives them time to adapt to the cooler weather and survive the winter. If you cover the seedlings with a layer of heavy row cover, snapdragons can survive the winters in zones 6 and above.
Pay attention to the variety if you’re hoping for tall stems that work well for arrangements. Environmental conditions impact stem height, but you can also find dwarf, intermediate, and tall varieties. Tall types benefit from support, so consider adding netting or growing them next to rigid stakes.
Pinching the seedlings when they’re young helps encourage branching and leads to a greater number of flower stalks. When the seedlings have three sets of true leaves, pinch off the top two leaves to encourage other stalks to develop.
Larkspur
Since larkspurs have a taproot, direct seeding is preferred to transplanting.
Larkspur’s tall, slender stalks covered with trumpet-shaped blooms make it one of my favorite cutting flowers. However, since it requires temperatures between 33-55°F (1-13°C) during the first six weeks of growth for proper flower development to occur, it’s sometimes difficult to grow. Planting in the fall ensures the plants receive the cold temperatures they need.
Since larkspur plants have a taproot, direct seeding is preferred to transplanting. Aim to sow the seeds so they receive the proper temperatures during their first six weeks of growth. Depending on where you live, September or October sowing is ideal. Larkspur seeds can take two to three weeks to germinate, so don’t worry if you don’t see seedlings emerge in the first week.
Once the seedlings appear, thin them so they’re four to six inches apart. Although they are frost-tolerant, covering with rover cover helps protect them when temperatures drop below 20°F (-7°C).
Stock
It’s best to start the seeds indoors and then transplant the seedlings into the garden.
A member of the brassica family, stock is known for beautiful and fragrant cut flowers that grow well from fall sowings. Unlike their kale and radish cousins, they are grown for their blooms rather than delicious greens or roots. The flowers have a fragrance similar to sweet cloves and come in various colors. Since the plants thrive in cool weather, they’re excellent candidates for fall planting.
Stock can survive temperatures down to 10°F (-12°C), so many growers can plant them in the fall. It’s best to start the seeds indoors and then transplant the seedlings into the garden. Depending on where you live, you can expect fall-planted seedlings to flower anytime from late winter to mid-spring.
When you’re growing stock, be aware that most varieties produce both single and double blooms. Many people prefer the appearance of the fuller double blooms and aim to select for these more desirable flowers. Stock seedlings vary in appearance depending on their bloom type, so you can remove single-flower blooms when the plants are young. Seedlings with a dark green color and deformed cotyledons often mature into plants that produce single flowers.
Foxglove
While you can direct sow and transplant foxglove, transplanting allows for more consistent germination and plant spacing.
Although many people think foxglove is a biennial, you can find both biennial and first-year varieties. Both of these cut flower varieties will bloom in the spring when you sow them the previous fall. That means you can enjoy a lush flush of beautiful bell-shaped blooms less than a year after planting the seeds!
While you can direct sow and transplant foxglove, transplanting allows for more consistent germination and plant spacing. Sowing the seeds in the middle the end of summer and transplanting the seedlings in the middle of fall is a good option. The plants will enjoy a cool period in the winter and send up a flower stalk the following spring. Foxglove grown in high tunnels and fields will produce stems that are multiple feet long, but those grown in tunnels will be noticeably longer.
After you cut the primary flower stalk, the plants will produce side shoots. You can continue cutting the stems and enjoy a harvest period that lasts multiple weeks.
Dianthus
If you sow seeds in the fall, they will begin producing flowers in the late winter to early spring.
Gardeners grow two main types of dianthus for cutting: carnations (Dianthus caryophyllus) and sweet William (Dianthus barbatus). Both of these species come in a range of colors, including pink, red, white, and purple. The flowers can survive the winter in many places with the help of a row cover and/or high tunnel.
One of the main advantages of planting dianthus in the fall is the early bloom time. If you sow seeds in the fall, the plants will begin producing flowers in the late winter to early spring. Not only will dianthus flower earlier, but you can rest assured you’ll end up with strong stems. Since warm temperatures above 65°F (18°C) can cause soft stems, planting in the spring can be risky.
It’s recommended that you sow seeds indoors and transplant the seedlings into your garden. Starting seeds in late summer and transplanting in mid-fall is a good option in many areas. When you plant, space the seedlings six inches apart and add hortonova netting about a foot above the ground to help support the stems.
Bells of Ireland
You can transplant or directly sow the seeds, but direct seeding is often easier and more successful.
Bells of Ireland is a unique cutting flower that thrives in cool weather, so fall sowing is ideal, especially in warm climates. The plants can easily survive the winter in warmer zones, and planting them in the fall ensures they have time to mature the following spring before the weather gets too hot.
Although Bells of Ireland produces tiny white flowers, its impressive greenery is what makes it a popular addition to cutting gardens. You can transplant or directly sow the seeds, but direct seeding is often easier and more successful. Since the seeds germinate best at temperatures in the 60s (~16°C), wait until the soil cools before sowing. Plant a few seeds per foot, then thin to one seedling per foot.
Bells of Irleand can tolerate light frosts, but you should protect it from heavy freezes. As long as you cover them with rover cover or plastic, they can survive in zones six and above. When the longer days of spring arrive, they’ll resume growing and send up tall flower stalks.
Orlaya
You can direct sow or transplant orlaya.
A great filler flower, orlaya produces many large, round, lacy blooms. However, the plants sometimes produce stems that are less than a foot tall, making them difficult to work into bouquets. One way to produce long stems is to plant the seeds in the fall and overwinter them for a spring harvest.
You can direct sow or transplant orlaya. No matter which option you choose, keep in mind that the seeds germinate best at temperatures between 60-70°F (16-21°C). Once the seedlings are a few months old, transplant them while leaving a foot between plants.
Orlaya can survive below-freezing temperatures, but covering the greens with row cover will provide added insulation. When spring arrives, the clumps of feathery foliage will begin sending up flower stalks. The plants will continue to produce new flowers for multiple weeks.
Bupleurum
The tiny seeds germinate best in temperatures below 65°F, so direct sowing them in the mid to late fall is best.
Bupleurum is another fall-sown cutting flower that acts as filler greenery in bouquets. The annuals produce umbels of small yellow or green flowers, and each bloom is surrounded by a yellow or green leaf-like structure known as a bracteole. When you add in long stems, the plants are stunning.
The tiny seeds germinate best in temperatures below 65°F (18°C), so direct sowing them in the mid to late fall is best. After the seedlings emerge, thin them so they’re four to ten inches apart. Cover with row cover when temperatures dip below freezing.
When spring arrives, bupleurum will continue growing and eventually send up tall flower stalks. Each plant produces around five stalks per plant, and they all bloom within a few weeks of each other. Therefore, you should succession plant bupleurum if you want to enjoy the crop over multiple months.
Ammi
The seeds germinate best at temperatures near 60°F (16°C), so wait until cool weather arrives before sowing.
Also known as false Queen Anne’s lace, ammi is a lacy flower with impressive cold tolerance. White flowers are the most common, but you can also find varieties with pink and purple blooms.
Since these flowers are members of the carrot family, they develop a strong taproot that makes them difficult to transplant. Therefore, direct seeding is the best option. The seeds germinate best at temperatures near 60°F (16°C), so wait until cool weather arrives before sowing. Make sure to keep the seeds moist until they germinate.
Although ammi is cold-tolerant, the plants will appreciate protection when temperatures drop below 25°F (-7°C). Adding a layer or two of row cover on top of plants is sufficient. As long as they survive the winter, they’ll send up tall flower stalks the following spring. Don’t be surprised if some of the flower stalks grow over your head! The plants will continue to flower for multiple weeks and provide a continuous harvest.cu
