Thalictrum delavayi 'Hewitt's Double' is a perennial plant known for its delicate and attractive flowers. It belongs to the Thalictrum genus and is commonly referred to as 'Hewitt's Double Meadow Rue'. 

Height/Spread: Thalictrum delavayi 'Hewitt's Double' typically grows to a height of 90-120 cm (35-47 inches) and has a spread of approximately 60-90 cm (24-35 inches).

Position: This plant thrives in partially shaded to sunny locations. It prefers a position that receives morning sunlight and afternoon shade, especially in areas with warmer summers.

Soil: Thalictrum delavayi 'Hewitt's Double' prefers well-drained soils that are rich in organic matter. It can tolerate various soil types, including loam, sandy loam, and clay loam, as long as the soil doesn't become waterlogged.

Flowering Season: In the Irish climate, Thalictrum delavayi 'Hewitt's Double' typically blooms in late spring to early summer. It produces clusters of double, fluffy, lavender-purple flowers that add a touch of elegance to the garden.

Uses: This plant is often used as an ornamental perennial in gardens, borders, and cottage-style landscapes. It provides a graceful and airy presence with its finely divided foliage and attractive flowers. Thalictrum delavayi 'Hewitt's Double' also attracts pollinators like bees and butterflies, making it beneficial for supporting local ecosystems.

Note: It's important to consider specific local conditions and microclimates when cultivating plants, as factors like regional variations in temperature, rainfall, and soil composition can influence their growth and performance.