Plant Montgomery Astilbe in spring or fall in a location with partial to full shade. Ensure the soil is consistently moist, well-draining, and rich in organic matter. Space plants about 18-24 inches apart. Water regularly, especially during dry spells, to maintain soil moisture. Fertilize in early spring with a balanced, slow-release fertilizer. Remove spent flowers to encourage new blooms. Divide clumps every 3-4 years in early spring to maintain vigor.