Gladioli

Gladioli, often referred to as "glads," are strikingly beautiful flowering plants known for their tall, sword-like foliage and vibrant, showy blooms. Belonging to the iris family (Iridaceae), these perennials are native to South Africa, where they thrive in warm, sunny environments. The flowers of gladioli grow along the length of a sturdy, upright stem, typically ranging from 2 to 4 feet tall, and they blossom in a wide array of colours, including red, pink, white, yellow, orange, purple, and even multicoloured varieties. Each stem of a gladiolus can bear up to 20 individual funnel-shaped flowers, which open sequentially from the bottom upwards, creating a cascading effect. This makes them popular as cut flowers for floral arrangements, where they add height, structure, and a touch of elegance. Gladioli are also a favorite in gardens, often planted in groups or rows for a dramatic display. These plants prefer well-drained soil and full sun, making them ideal for summer gardens. Though relatively easy to care for, they require some support to prevent the tall stems from toppling over, especially in windy conditions. Gladioli are typically planted from corms in the spring, and with proper care, they bloom in late summer. In the language of flowers, gladioli symbolize strength of character, integrity, and remembrance, making them a meaningful addition to both celebratory and memorial settings. Their striking appearance and rich symbolism ensure that gladioli continue to be cherished in gardens and bouquets alike.

How To Grow

Growing gladioli is a rewarding experience, as these plants can bring stunning colour and height to your garden. Here's a step-by-step guide on how to grow gladioli:

  1. Choose the Right Location Sunlight: Gladioli thrive in full sun, so choose a location that receives at least 6-8 hours of direct sunlight each day. Soil: They prefer well-drained soil with a slightly acidic to neutral pH (6.0-7.0). If your soil is heavy or clay-like, consider amending it with compost or sand to improve drainage.
  2. Prepare the Soil Loosen the soil to a depth of about 12 inches. Mix in compost or well-rotted manure to enrich the soil and improve drainage. If necessary, test the soil pH and adjust with lime or sulphur to achieve the desired pH level.
  3. Planting the Corms Timing: Plant gladiolus corms in the spring after the danger of frost has passed and the soil has warmed to at least 55°F (13°C). For a continuous bloom, you can plant corms every two weeks until early summer. Depth and Spacing: Dig holes about 4-6 inches deep and place the corms pointed side up. Space the corms 6-8 inches apart. Cover the corms with soil and water them thoroughly.
  4. Watering Water the corms well after planting and keep the soil consistently moist but not waterlogged. Gladioli require about 1 inch of water per week, either from rainfall or supplemental watering. Avoid overhead watering to reduce the risk of fungal diseases; instead, water at the base of the plants.
  5. Fertilizing Apply a balanced, slow-release fertilizer (such as 10-10-10) at planting time. As the plants grow, you can feed them with a high-potassium fertilizer to encourage strong stems and vibrant flowers. Avoid excessive nitrogen, which can lead to weak stems and fewer blooms.
  6. Staking Gladioli can grow tall, so staking may be necessary to support the stems, especially in windy areas. Place stakes or plant supports when the plants are about 12 inches tall. Tie the stems to the stakes loosely to avoid damaging the plants.
  7. Mulching Apply a layer of mulch around the plants to help retain moisture, suppress weeds, and keep the soil temperature stable. Organic mulches like straw, bark, or compost work well for this purpose.
  8. Caring for the Blooms As the flowers bloom, cut the stems for floral arrangements, leaving at least 4 leaves on the plant to ensure the corm continues to develop for the next year. Remove faded flowers to encourage more blooms and prevent the plant from directing energy into seed production.
  9. End of Season Care After the first frost in the fall, it's time to dig up the corms for winter storage, especially in colder climates where the ground freezes. Cut the stems down to about 2 inches above the corms. Carefully dig up the corms and shake off excess soil. Let them dry in a warm, airy place for a few days.
  10. Storing Corms Once dry, remove the old shrivelled corms and any remnants of the stems. Store the healthy corms in a cool, dry place, such as a basement or garage, at around 40-50°F (4-10°C). Place them in paper bags, mesh bags, or boxes with ventilation to prevent moisture build-up.
  11. Replanting In the following spring, replant the corms as described above for another season of beautiful gladiolus blooms. By following these steps, you'll be able to grow gladioli successfully, bringing vibrant, tall flowers to your garden year after year.

How/When To Harvesting

Harvesting gladioli at the right time and in the correct manner ensures that you enjoy their beautiful blooms for as long as possible, whether in a vase or left in the garden. Here's how to harvest gladioli properly:

  1. Timing the Harvest Ideal Stage: Harvest gladioli when the lowest two or three flowers on the spike have started to open. The remaining buds on the stem will continue to open over time, ensuring a prolonged display. Early Morning or Late Evening: The best time to harvest gladioli is early in the morning or late in the evening when temperatures are cooler. This helps prevent wilting and retains the moisture content in the stems.
  2. Tools and Preparation Sharp Knife or Pruners: Use a clean, sharp knife or garden pruners to make a clean cut. Dull tools can crush the stem, reducing the vase life of the flowers. Bucket of Water: Have a bucket of cool, clean water ready to place the stems in immediately after cutting. This helps prevent air bubbles from entering the stems, which can block water uptake.
  3. Cutting the Stems Angle of Cut: Cut the stem at a 45-degree angle. This increases the surface area for water absorption and helps prevent the stem from sitting flat against the bottom of the vase, which could block water intake. Leave Leaves Behind: When cutting the stem, make sure to leave at least 4-5 healthy leaves on the plant. These leaves are essential for photosynthesis, which helps the corm store energy for the next growing season.
  4. Post-Harvest Care Immediate Hydration: Immediately place the cut stems in the bucket of water. Let them rest in a cool, shady spot for a few hours before arranging them in a vase. Conditioning: To extend the life of the flowers, you can add floral preservative to the water. If you don't have any, a homemade solution of 1 teaspoon of sugar and a few drops of bleach in 1 quart of water can help. Water Temperature: Use lukewarm water for the vase, as it helps the stems absorb water more efficiently. Cold water can shock the flowers, reducing their lifespan.
  5. Arranging the Flowers Vase Selection: Choose a tall vase to support the long stems of the gladioli. Ensure the vase is clean to prevent bacterial growth. Trimming: Re-cut the stems at a slight angle before placing them in the vase. Remove any leaves that will be submerged in water to prevent decay and bacterial growth. Positioning: Arrange the gladioli in the vase, ensuring the tallest stems are in the centre, with shorter stems around the edges. This creates a balanced, visually appealing display.
  6. Maintaining the Arrangement Water Maintenance: Change the water every two days, re-cutting the stems each time to improve water absorption. Keep the vase away from direct sunlight, heat sources, and drafts to prolong the life of the blooms. Removing Spent Flowers: As the individual flowers fade, pinch them off to keep the arrangement looking fresh. The remaining buds will continue to open over several days.
  7. Post-Bloom Care Garden Plants: After harvesting, allow the remaining leaves on the plant to continue growing. These leaves will help the corms mature and store energy for the next season. Cut back the leaves only after they have yellowed and died back naturally. Corm Storage: If you plan to dig up and store the corms for the winter, wait until the foliage has died back completely before digging them up.

Planting Schedules for Location: London, City of London

Sow Direct

JFMAMJJASOND
Sow Direct
Harvest

Sow Indoors / Plant Out

JFMAMJJASOND
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