15 Things All Delphinium Owners Must Know

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Flowers bring life and color to our garden, and the delphinium stands out with its stunning beauty. Like many ornamental plants, these delicate flowers require special care and attention. Here are a few planting, growing, and caring tips to help you handle these perennials despite their short lifespan.

Understand Their Symbolism

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Delphinium flowers got their name from the Greek word “delphis,” meaning dolphin. The shape of the flowers looks like a dolphin’s nose, so they were named after it. In stories, their flowers represent positivity, joy, and goodwill. People also believe they bring good vibes and cheer up anyone who sees them.

Identify the Ideal Temperature and Humidity

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The temperature for growing these beauties in your garden should be between 60-70°F (15-21°C) with moderate humidity levels. They prefer full sunlight for at least 6 hours a day, and humid conditions make them vulnerable to mildew infestation.

Use the Right Soil Type and pH


Before planting delphiniums in your garden, it’s essential to ensure the soil type is draining and rich in nutrients. A moist loam with a good balance of acidity helps them grow healthy and strong. Please place them in a slightly acidic area to a neutral pH level, around 6.0 to 7.0.

Keep Track of the Blooming Season

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When delphinium flowers bloom, they show off their pretty leaves, which look like colorful towers. They can be blue, pink, purple, or white. They also grow tall, reaching up to 6 feet, so figure out which kind you’re planting to give it enough space to grow.

Beware of Toxicity

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Though beautiful, they contain poisonous chemicals like methyllycaconitine, which are toxic to humans and animals. Please don’t touch them with your bare hands or put them in your mouth. Keep them away from pets like cats and dogs; they can get sick if they eat the flowers. Their seeds have about 1.4% diterpenoid alkaloids, which can cause severe digestive issues.

Follows Pre-Plantings Tips

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Since delphiniums love sunlight, the best time to seed them is late spring or early summer. Avoid extreme heat or cold, and ensure you use fresh seeds. Also, when sowing the seeds, start ten weeks before the final day of spring frost and dig a 1-foot hole twice as wide as the roots.

Take Planting Measures


When planting delphiniums, prepare the soil with mulch, place them in the hole, and gently cover it up. Ensure the top of the root ball is level with the ground, and then mix in some compost or manure. Afterward, water the area, and the seedlings will sprout in four weeks.

Grow and Care for them After Planting

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Delphiniums must be watered once a week, especially during hot weather, but you don’t waterlog the soil. Place them 2-4 inches apart for spacing, as overcrowding will affect air circulation and cause fungal issues. Furthermore, cover them with mulch during winter to protect them from the cold.

Provide Stake Support

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Use wooden stakes and garden twine to gently tie the stem to the stake. Place the stake close to the plant without damaging the roots. As the delphinium grows, adjust the knots to provide proper support. This method helps prevent it from bending or breaking in strong winds.

Add Fertilizer

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While organic fertilizers are the best, adding artificial ones like 10-10-10 (balanced) can help delphinium grow better. Sprinkle just one tablespoon around young shoots, as too much can harm them, then avoid using too little to prevent stunted growth. Overall, follow the instructions on the fertilizer package to know how much to use and get the best results.

Maintain the Right Soil Moisture

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Delphinium likes its soil to be moist but not soaking wet. Grab a handful in your palm to check the moisture. If it feels dry, it’s time to water the area; however, be careful not to overwater it since it can rot the roots. Also, the plant will wilt if you let the soil dry out completely.

Propagate Young Plants


The best time to propagate is during the early spring. Use a small shovel or garden trowel to carefully dig up small sections of the parent plant with the root system attached. Set them in pots with soil, water them regularly, and keep them in a sunny spot.

Prune and Care for Flower Spikes


Remove any dead or wilted flowers regularly to care for the flower spikes. Thinning the shoots helps the delphinium focus its energy on growing new, beautiful flowers. Leave 5–7 stalks on mature plants and keep 2-3 shoots on younger ones.

Avoid Pests and Diseases


Nematodes, snails, slugs, and critters such as aphids are common pests that may infest your delphinium. You can pick off the bugs or use insecticidal soap, but wear gloves. They can also get diseases like powdery mildew, gray mold, or botrytis when the weather is too humid. The best measures are to remove affected plants, improve air circulation, and use fungicides.

Know the Best Companion Plants

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Salvias, hyssops bloom, and Joe Pye weeds are perfect because they grow during winter and beautify the environment when delphiniums aren’t flowering. Likewise, lavender and daisies pair well based on color and scent. You can do more research and see what other compatible companions you can find to decorate your garden.


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