Katz Hi Double White Matthiola

Katz Hi Double White is a white-flowered stock selection with an upright habit and a listed height of 32 inches. PanAmerican Seed reports that more than 90% of its usable stems carry double flowers, distinguishing this selection from the regular Katz White line. ## Flowering and form The exact developer page lists spring and autumn flowering, sun exposure, and suitability for high-tunnel or field production. It describes shorter crop time, uniform stem length and timing, and better heat tolerance than European or traditional field types. The page also notes that growers can schedule flowering across a broader part of the year in some climates; this production flexibility does not establish year-round outdoor bloom everywhere. ## Garden growing Matthiola incana is a cool-season plant. North Carolina State Extension recommends full sun and average to humusy, consistently moist, well-drained soil; the species tends to decline as temperatures rise above 80°F. The Katz Hi Double line’s improved heat tolerance is relative to traditional stock types, so local climate still affects garden performance. Sources: [PanAmerican Seed: Katz Hi Double White](https://www.panamseed.com/Products/074608731005863/matthiola-katz-hi-double-white/); [North Carolina Extension Gardener Plant Toolbox: Matthiola incana](https://plants.ces.ncsu.edu/plants/matthiola-incana/). ## Maintenance Choose a sunny, freely draining site and keep soil evenly moist during active growth. Plan for the milder parts of the year in hot climates, since species-level stock performance declines as temperatures rise.