How to Grow Veronica longifolia
Veronica longifolia
Veronica longifolia is a tall, fully hardy border perennial that bears long spikes of blue-violet to lilac flowers from July to September — later and taller than V. spicata. Plant in full sun to light shade in well-drained soil, spacing 45 cm apart. Stake in exposed positions before stems reach full height. Cut spent spikes back after the first flush to encourage rebloom. A magnet for bees and butterflies. Divide every three to four years to keep clumps vigorous.
Yearly Lifecycle
Care Essentials
Apply a light balanced feed in spring as new growth emerges. Veronica longifolia is not a heavy feeder; avoid high-nitrogen feeds which encourage leafy growth at the expense of flower spikes.
Watch For
- Powdery mildew in dry spells
- Slugs on young spring growth
- Downy mildew in wet conditions
- Aphids on shoot tips
Companions
Echinacea, Salvia, Phlox, Rudbeckia
Care Requirements
Light
Full sun to partial shade
Flowers best in full sun, producing the tallest, most upright spikes. Tolerates light shade but may require staking in shadier positions where stems reach for light.
Watering
Regular moisture, good drainage essential
Water regularly during dry spells, especially in the first season while establishing. Once settled, tolerates short dry periods. Avoid waterlogged soil, which can cause crown rot.
Fertilizing
Light balanced feed in spring
A light dressing of balanced granular fertilizer or compost mulch in spring is sufficient. Heavy feeding, especially with nitrogen, produces lush leafy growth at the expense of flowering.
Pruning
Deadhead after first flush, cut to ground in autumn or spring
Cut spent spikes back to a side shoot after the first flowering to encourage rebloom. Remove all top growth to ground level in late autumn or leave for wildlife and cut back in early spring.
Spacing
45 cm apart
Space plants 45 cm apart to allow for mature clump size and good air circulation. Groups of three or more at this spacing create the best border impact.
Support
Stake in exposed positions
In windy or exposed borders, place grow-through supports or link stakes in late spring before stems reach 50 cm. Plants in sheltered positions with full sun rarely need staking.
Growing Tips
Stake before flowering
Tall stems can flop in exposed borders. Place grow-through supports or link stakes in late spring before stems reach 50 cm.
Cut back for a second flush
After the first flowering, cut spent spikes back to a side shoot. Most plants will produce a second, lighter flush of flowers in late summer.
Plant in groups
Three or more plants together create a bold late-summer display and provide more foraging opportunities for bees and butterflies.
Divide every few years
Clumps become congested after three to four years. Lift and divide in spring or autumn, replanting the healthiest outer portions.
Spacing & Planting
| Plant spacing | 45 cm |
| Row spacing | 60 cm |
| Mature height | 100 cm |
| Mature spread | 45 cm |
Space 45 cm apart in borders to allow for the taller, more robust clumps. Groups of three or more create the best visual impact.
