Dahlia

Dahlias are vibrant and versatile flowering plants known for their stunning variety of shapes, sizes, and colours. Originating from Mexico and Central America, dahlias belong to the Asteraceae family, which also includes daisies and sunflowers. These perennial plants have become a favourite among gardeners and flower enthusiasts due to their showy, intricate blooms that range from small, delicate pom-poms to large, dinner-plate-sized blossoms. Dahlia flowers come in an array of colours, including shades of red, pink, yellow, orange, purple, and white, as well as bi-coloured and multi-coloured varieties. The petals can be smooth, fringed, or even cactus-like, adding to the plant's visual appeal. Dahlias typically bloom from midsummer through the first frost, providing a long-lasting display of color in gardens and floral arrangements. The plants vary in height, with some dwarf varieties growing as short as 12 inches, while others can reach up to 6 feet tall. They thrive in well-drained, fertile soil and prefer full sun, making them ideal for garden beds, borders, and containers. While dahlias are perennial in warmer climates, they are often grown as annuals in cooler regions, with tubers being dug up and stored during the winter. Beyond their ornamental use, dahlias hold symbolic meanings in various cultures, representing elegance, inner strength, and creativity. Whether used in a formal garden setting or as a cut flower in a bouquet, dahlias bring a touch of vibrant beauty and sophistication to any space.

How To Grow

Growing dahlias can be a rewarding experience, as these beautiful flowers can add vibrant colour and texture to any garden. Here's a step-by-step guide on how to grow dahlias:

  1. Choose the Right Dahlia Variety Select your dahlia variety based on your garden space, as they come in various sizes from compact, small-flowered types to large, towering varieties. Check your hardiness zone: Dahlias are generally hardy in USDA zones 8-11, but they can be grown as annuals in cooler climates or overwintered indoors.

  2. Prepare the Soil Pick a sunny location: Dahlias need at least 6-8 hours of direct sunlight each day. Ensure well-draining soil: Dahlias thrive in well-drained, fertile soil. If your soil is heavy or clay-like, amend it with compost or sand to improve drainage. Soil pH: Aim for a slightly acidic to neutral soil pH of 6.0 to 7.5.

  3. Planting Dahlias Planting tubers: Wait until the soil has warmed up to at least 60°F (15°C), usually after the last frost in spring. Dig a hole about 6-8 inches deep. Place the tuber horizontally with the "eye" (where the sprout will emerge) facing up, and cover it with 2-3 inches of soil. As the plant grows, gradually fill in the hole with more soil. Spacing: Space taller varieties 2-3 feet apart and shorter ones about 1-2 feet apart. Support: For larger varieties, insert stakes or tomato cages at the time of planting to support the plants as they grow.

  4. Watering and Feeding Watering: Water thoroughly after planting, but avoid overwatering as tubers can rot in soggy soil. Once established, water deeply 2-3 times a week, depending on the weather. Keep the soil evenly moist, especially during dry periods. Fertilizing: Start feeding your dahlias with a low-nitrogen fertilizer (such as 5-10-10) about 3-4 weeks after planting. Repeat every 3-4 weeks during the growing season. Avoid fertilizers high in nitrogen, as they promote leafy growth at the expense of flowers.

  5. Caring for Dahlias Pinching: When your dahlia plants are about 12 inches tall, pinch off the top 3-4 inches to encourage bushier growth and more blooms. Deadheading: Regularly remove spent flowers to encourage continuous blooming throughout the season. Pest and disease control: Watch for common pests like aphids, slugs, and earwigs. Treat with appropriate organic or chemical controls if necessary. Keep an eye out for powdery mildew or other fungal diseases, and ensure good air circulation around the plants.

  6. Overwintering Dahlias In warmer climates: Dahlias can be left in the ground. Mulch heavily to protect them during the winter. In cooler climates: After the first frost kills the foliage, carefully dig up the tubers, leaving a small stem attached. Let the tubers dry in a cool, dry place for a few days, then store them in a box filled with peat moss, vermiculite, or sand. Keep the box in a cool, dark, frost-free place (around 40-50°F or 4-10°C) until spring.

  7. Replanting in Spring Inspect stored tubers for any signs of rot or disease before replanting in the spring. Divide large clumps of tubers if desired, ensuring each division has at least one "eye."

  8. Enjoy Your Dahlias! As your dahlias bloom, cut flowers regularly for indoor arrangements, which can also encourage more blooms in the garden. With proper care, dahlias will reward you with stunning flowers from midsummer until the first frost.

How/When To Harvesting

Harvesting dahlias at the right time and with proper technique ensures that you get the most out of these stunning flowers, whether for garden enjoyment or cut flower arrangements. Here's a guide on how to harvest dahlias:

  1. Timing the Harvest Harvest in the morning or late afternoon: The best time to harvest dahlias is early in the morning or late in the afternoon when temperatures are cooler. This helps the flowers stay hydrated and fresh for longer. Wait for the right stage: Dahlias should be harvested when the flowers are fully open but before they start to fade. The petals should be firm and vibrant, and the center should be fully developed. Avoid cutting buds that are too tight, as they may not open fully after cutting.

  2. Prepare Your Tools Use sharp, clean shears or scissors: To prevent damage to the plant and ensure a clean cut, use sharp and sterilized tools. This helps reduce the risk of disease transmission. Have a clean bucket of water ready: Prepare a bucket filled with cool, clean water to place the cut stems in immediately after harvesting.

  3. Cutting the Stems Choose the longest stems: When selecting flowers to cut, choose those with long stems, as this allows more flexibility in arranging and ensures a healthier regrowth of the plant. Cut at an angle: Make a diagonal cut on the stem about 1/4 inch above a set of leaves or a node. Cutting at an angle increases the surface area for water absorption and helps prevent the stem from sitting flat on the bottom of the vase, which can block water uptake. Remove lower leaves: Strip any leaves that will be below the water line in the vase. Leaves left in water can rot and cause bacteria to grow, shortening the vase life of the flowers.

  4. Conditioning the Flowers Immediately place the stems in water: After cutting, immediately place the stems in the bucket of water to prevent them from wilting. Condition the flowers: Allow the dahlias to sit in a cool, dark place for a few hours to overnight to condition them. This process helps them last longer by allowing them to fully hydrate.

  5. Storing and Arranging Store in a cool place: If you’re not arranging them immediately, keep the dahlias in a cool, dark place until you’re ready to use them. Refresh the water daily: Change the water in the vase every day or two to keep it fresh and add a floral preservative if desired. Trim the stems slightly each time you change the water to maintain water uptake.

  6. Caring for the Plant After Harvest Deadheading: Continue to deadhead spent blooms on the plant to encourage more flowering throughout the season. Support the plant: If you’re cutting a significant number of flowers, consider providing extra support to the plant, as removing blooms can sometimes destabilize taller varieties.

  7. Enjoy Your Dahlias Whether arranging them in a vase or displaying them in a bouquet, freshly harvested dahlias can brighten up any space. With proper care, they can last up to a week or more as cut flowers.

Planting Schedules for Location: London, City of London

Sow Indoors / Plant Out

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Sow Indoors
Plant Out
Harvest
  • Sow Depth: 15 cm
  • Spacing Between Rows: 30 cm
  • Spacing Along Row: 30 cm
  • Number plants per Square Foot: 2