🌸 Delphiniums and lupins are two of the most striking perennials in the early summer garden. With their tall, colourful spires and stately presence, they bring structure and classic charm to herbaceous borders, particularly in cottage and traditional gardens. May is the key month to care for them—set them up well now, and you’ll be rewarded with strong, healthy plants and long-lasting blooms.
Here’s how to keep your delphiniums and lupins thriving this month:
🪴 1. Stake Before They Flop
Both delphiniums and lupins can grow rapidly in May—delphiniums often shoot up over a metre tall in a few weeks. To prevent wind or rain damage:
- Stake early, before the stems become too tall or heavy.
- Use bamboo canes and soft ties, metal grow-through rings, or purpose-built plant supports.
- For delphiniums, consider using multiple stakes in a circle for best support.
This helps avoid that heartbreaking moment when a storm flattens your tallest flower just before it blooms.
💧 2. Water Deeply and Regularly
These are thirsty plants, especially delphiniums. In dry springs, make sure to:
- Water at the base, deeply and consistently.
- Avoid splashing leaves to reduce fungal risk.
- Mulch around the base with compost or well-rotted manure to lock in moisture.
🌿 3. Feed for Vigour and Colour
To support lush foliage and abundant flowers:
- Feed with a high-potash fertiliser (like tomato feed) every two to three weeks.
- If plants are newly established, start with a balanced feed, then switch to high-potash as buds form.
Feeding now ensures strong flowering and helps build strength for next year’s growth.
🐌 4. Protect from Pests
Delphiniums in particular are a favourite snack of slugs and snails. Protect your plants by:
- Laying down organic slug pellets, wool pellets, or copper barriers.
- Checking the plants after dark and removing pests by hand if needed.
- Keeping the area tidy and free of hiding places like old pots or debris.
Young lupin growth is also vulnerable, though slightly tougher once established.
✂️ 5. Deadhead for Repeat Blooming
Lupins can flower more than once in a season with prompt deadheading:
- As soon as flower spikes fade and start to set seed, cut them back to the base of the stem.
- This can encourage a second flush in late summer.
Delphiniums may also re-flower if cut down after the first bloom—especially in warm summers.
📌 Quick Tips at a Glance:
- Stake tall stems before they lean or fall
- Water deeply during dry weather
- Feed with a potash-rich fertiliser
- Protect against slugs and snails
- Deadhead lupins to prolong flowering
- Mulch around the base to conserve moisture
With the right care in May, your delphiniums and lupins will shoot skyward and fill your garden with towering colour and grace. These classic perennials are worth the attention—and will be the pride of your garden all through June and beyond.
