Growing Flat sea holly 'Blue Hobbit' in a pot

Once established, Eryngium planum 'Blue Hobbit' is exceptionally low-maintenance and thrives on neglect. Water only during prolonged dry spells in the first growing season to help roots establish; thereafter it tolerates drought admirably and needs no supplementary watering in most years. Overwatering or poorly drained soil is the main killer, so err on the dry side. Feed sparingly. In April or May, scatter a light dressing of general-purpose granular fertiliser (such as blood, fish and bone) around the base, or apply a single handful of slow-release pellets. Avoid high-nitrogen feeds, which produce lush foliage at the expense of flowers and reduce winter hardiness. On fertile soils, feeding may be unnecessary altogether; eryngiums perform well in lean conditions and can become floppy if overfed. 'Blue Hobbit' is fully hardy in zones 4–9 and requires no winter protection in temperate Europe. The crown is tough, but good drainage is critical during wet winters. If your soil is heavy, a top-dressing of grit around the crown in autumn helps prevent waterlogging and rot. Pests are rarely a problem. Slugs and snails occasionally nibble emerging shoots in spring; inspect regularly and remove by hand or use organic pellets if damage is severe. Powdery mildew can appear on foliage in hot, dry summers but seldom affects flowering; improve air circulation by spacing plants properly and avoid overhead watering. Aphids sometimes cluster on flower stems but are easily hosed off. Root rot is the only serious threat, caused by poor drainage rather than disease. Mulch lightly with gravel, not organic matter, to keep the crown dry and discourage fungal issues.