Whenever you come across a garden with sea holly, it’s hard not to be captivated by its unique beauty. The striking blue hues and long-lasting flowers make it a favorite among sun gardeners. Best of all, this plant is incredibly low-maintenance and thrives in areas where other plants struggle to grow. It’s perfect for those hot and dry spots in your garden, and will add a touch of elegance and charm in the mid-summer months. Let’s explore how to properly grow and care for this perennial flower.
This plant belongs to the category of herbaceous perennials that can survive for a long time. It has the ability to grow in soil with different pH levels ranging from acidic to alkaline. Its origin can be traced back to Europe and China. The blooming period of this plant occurs during summer and fall, producing beautiful blue and purple flowers. However, it is prone to diseases like powdery mildew and leaf spot, as well as pests such as aphids, slugs, and snails. The history of this plant is fascinating and worth exploring.
The Eryngium planum, also known as flat sea holly, is a member of the carrot family and has deep tap roots which were used for both medicinal and culinary purposes in the past. This plant is originally from Europe and Central China and belongs to the Eryngium genus, which was once used to treat various illnesses. The long taproots were eaten like carrots and potatoes. Additionally, this plant is now widely cultivated for its beauty. It has been hybridized to create different varieties that gardeners and florists can enjoy. The flowering stems are long-lasting and can be dried easily, making it a popular choice for decoration.
There are various types of Eryngium that have unique features such as different showiness, bract size, and flower cone dimensions. In addition to the well-known flat sea holly, there are other types of Eryngium including the Alpine sea holly, Amethyst sea holly, Mediterranean sea holly, sea holly, and Giant sea holly. All of these varieties thrive in full sun and can grow up to 3 feet tall and 5 feet wide. Their blooms, which occur from mid-summer to fall, may differ in terms of frilliness, bract width, or cone size. These plants can be propagated by root cuttings or seeds.
Propagation through root cuttings can be a challenging yet satisfying process. However, it is important to note that this method can only be done when the plant is in its dormant state. If your sea holly is not dormant, do not attempt to propagate it through root division. Root cuttings ensure that your plant will be an exact clone of its parent, making it ideal for propagating specific cultivars. To get started, prepare the necessary equipment such as pre-dampened potting mix, a trowel, and sterile snips or pruning shears. While rooting hormone may be helpful, it is not absolutely necessary. Once you have gathered all the materials, dig up the dormant plant and rinse the dirt off its roots to expose them. Select a few healthy roots with a diameter similar to a pencil, ensuring that you do not cut off more than 1/3 of the plant’s root system. Work quickly to prevent damage to the roots and immediately replant the parent plant to reduce shock. Cut approximately 3 inches of the selected roots, making a flat cut followed by a 3-inch angled cut. If using rooting hormone, apply it before planting the root cutting angled side down and cover it entirely, leaving the flat cut just below the soil’s surface. Repeat the same process with the remaining root segments and plant them accordingly. Keep the soil damp but not too wet and protect the potted roots during winter. By springtime, new shoots should start developing from the root cuttings.
During the fall, you can harvest the mature seed heads of sea holly by cutting them off and placing them in a paper bag. This will allow the seeds to naturally fall off and keep them all together. You can either sow the seeds immediately or refrigerate them over winter for spring planting. If you decide to purchase seeds, they are available at your local garden center. Another option is to buy a sea holly plant from a nursery or garden center.
Ensuring the straightness of taproots is crucial when planting, so make sure the hole you dig is deep enough to accommodate them. You can buy bare-root or potted plants from your local nursery or start from seed indoors. In case of bare-root sea holly plants, remove them from their damp wood chip packaging and soak them in water before planting. Dig a hole that’s twice as wide as the root ball and carefully place the plant in it, making sure not to bunch up the roots. Backfill with garden soil and water lightly. For potted plants, remove them from their pot and untangle any circling roots before planting. Keep the taproot straight and backfill with garden soil to the same depth as it was planted in the pot. Keep your eye on the plant and the soil it’s growing in, watering it lightly to keep it moist without over-watering it.
To achieve better results, it is recommended to sow seeds directly in the fall for cold stratification. There are two options for planting from seeds: starting them indoors or sowing them directly into the soil. For those who choose to start their seeds indoors, it is important to do so 10-12 weeks prior to the average last frost. Prior to planting, it is advised to refrigerate the seeds for at least 2-3 months and then allow them to come to room temperature before gently pressing them into the potting mix. It is important not to cover the seeds with soil but to keep the soil lightly moist. Once the seedlings have sprouted and grown a few inches tall, they should be hardened off to outdoor conditions before being transplanted outside.
For those who choose to directly sow their seeds outdoors, it is recommended to plant them in the fall. It is important to prepare the planting location and firmly press the seeds against the soil’s surface without covering them with soil. The soil should be kept moist. These plants require vernalization or exposure to cold temperatures for them to germinate. Sea holly, in particular, requires light to germinate in the spring, so it is important to press these seeds firmly onto the soil’s surface without covering them. However, it is important to note that sea holly is slow to germinate and can take up to 90 days to sprout.
Once you have successfully grown a healthy plant in your garden, it is important to explore care for these perennials.
To ensure that your sea holly plants thrive, make sure they get a good dose of sunlight. Aim for at least 8 hours of direct sunlight each day. Although they can tolerate some shade, too much of it may result in weaker plants that won’t be able to hold up the weight of their gorgeous flowers.
Sea holly is a drought-resistant plant once it has a deep taproot that allows it to tolerate dry conditions. This perennial’s taproot is lengthy and helps it survive during extended periods of drought, making it low-maintenance. Nevertheless, it’s important to water the plant occasionally to ensure it produces flowers. For best results, water the plant directly at its base to prevent water from accumulating around the plant and causing the crown to rot if the soil holds too much moisture.
If you want to keep this plant healthy, it’s important to remember that it loves sandy and well-drained soil. While it can tolerate poor fertility, you should be careful not to overwater it or let it sit in wet soil for too long. Root rot can quickly set in and cause the taproot to deteriorate, leading to a lack of water and nutrients for the rest of the plant.
Sea holly is a tough plant that can thrive in various climates, including zones 4-9, as long as it is planted within its hardiness range. It can withstand humidity, salt, and dryness without any other specific climate requirements.
To maintain these plants, it’s best to avoid fertilizing them. They actually do better in poor soil, as they are perennials that thrive under those conditions. Over-fertilizing can cause them to grow excessively and sprawl out, so it’s best to avoid it altogether.
Sea holly is a plant that requires little maintenance once it is established. You can simply sit back and enjoy its unique flowers. While deadheading the spent blossoms can help to promote new flowering and lengthen the bloom time, the drying flowers on the plant can provide continued interest in your garden throughout fall and winter. At the end of the growing season, cutting the plant down to the ground is optional, as the dried flowers can still add a fun look to your winter garden. However, it is important to protect the rosettes of foliage from the winter by placing leaves or evergreen needles on top. To create an intriguing diversity of spiky blooms, you can mix-and-match your favorite varieties.
‘Blue Cap’ is a delightful plant variety that features silver stems and striking blue bracts, making it perfect for mass planting in your hot perennial beds or as a border plant. This clump-forming plant grows up to 2-3 feet tall and 1-2 feet wide, and thrives in Hardiness Zones 4-8. The unique combination of silver-blue flowers and blue bracts make this plant a popular choice among garden enthusiasts. You can add a touch of elegance to your garden by planting ‘Blue Cap’ either on its own or in a mass. Its egg-shaped flowers clustered together with the blue bracts create a stunning visual effect that is sure to impress.
With its stunning blue-green leaves and silver stems, ‘Blue Glitter’ is certainly a variety worth having. It grows well in Hardiness Zones 4-8 and can reach a height of 2-3 feet while spreading out to about 1-2 feet wide. Its beautiful silver-blue flowers add an extra touch of elegance to your garden, making it stand out from the rest. What sets ‘Blue Glitter’ apart from other varieties is that it matures faster and produces more blossoms, making it an improved version of the original. The deeply toothed blue-green leaves are low-growing from strikingly silver stems, making this variety a truly unique addition to your garden.
The ‘Blue Hobbit’ is a fantastic option for smaller garden spaces. Its compact size makes it perfect for planting in the front of flower beds or raised garden beds. The plant grows to be around 8 inches to 1 foot tall, with a width of 6 inches to 1 foot. The flowers are a beautiful shade of purple-blue and are held up by sturdy silver-blue stems. Compared to other sea holly varieties, the ‘Blue Hobbit’ has a slightly more purple tint to its blooms. These flowers are also known for their long-lasting beauty. The ‘Blue Hobbit’ is hardy in zones 4-8.
If you’re looking for a stunning addition to your cutting garden, consider the ‘Steel Blue’ variety. This particular plant is known for its tall stature and elegant steel-blue flowers. With long stems reaching up to 4 feet in height and 1-2 feet in width, ‘Steel Blue’ makes for the perfect addition to any cutting garden. Not only does it add a touch of elegance and beauty, but it also offers versatility as its long stems make it easy to add to any vase arrangement. With a classic steel-blue flower color that can grow up to an inch in diameter, ‘Steel Blue’ is a must-have for any cutting garden enthusiast. It also has a hardiness zone of 5-9, meaning it can thrive in a range of climates.
Looking for a plant that will complement your garden’s color scheme without resorting to blue or purple shades? Look no further than the ‘White Glitter’ variety. With its silver-white hues and green stems, this plant offers a unique and eye-catching twist on traditional blue varieties. Plus, at 2-3 feet tall and 1-2 feet wide, it’s the perfect size for any garden. So why not give ‘White Glitter’ a try and add some silvery shine to your outdoor space?
Sea hollies have a natural resistance to insects, thanks to their spiky exterior and typical surroundings. As a result, they don’t attract too many bugs. However, if grown in shady areas, aphids, slugs, and snails can infest the plant’s lower leaves. To prevent this, plant them in full sun. If the issue persists, handpicking the slugs and snails is an option, although an organic bait purchased from a garden center is a more comfortable alternative.
Sea hollies typically flourish in conditions that are resistant to diseases. Nevertheless, it is possible for them to be affected by fungal infections like powdery mildew and leaf spot if they are grown in moist environments. In case of such infections, copper fungicides may be used for treatment. To prevent the occurrence of diseases, it is important to provide enough space for each plant to allow for proper airflow and to keep moisture away from the leaves. Damp leaves increase the likelihood of fungal spores being trapped in the moisture and spreading.
If you’re looking for a plant that thrives in sunny areas with poor soil, sea holly is an excellent choice. This perennial can be mass-planted or used as a standalone feature and adds a spunky touch to any garden. The blooms are perfect for cutting and make stunning accents in vases and bouquets. As the flowers mature, they produce seeds that can self-seed throughout your garden. If you don’t want this to happen, simply deadhead the flowers when they fade. While sea holly is not commonly grown in containers, it can be done by mixing succulent potting soil with regular soil. However, be prepared to re-pot the plant as sea holly does not transplant easily. Once established, sea holly does not like to be moved due to its long taproot. If you notice browning of foliage, check the plant’s water intake as too much moisture can cause this issue. Overall, sea holly is a beautiful, low-maintenance plant that adds beauty to any hot and sunny garden.