Outsidepride Ageratum Yellow - 5000 Seeds Ageratum Yellow seed grows best in full sun in USDA Zones: 4 - 8. These golden-yellow heirloom flowers are a hardy summer annual that can withstand all types of weather. Lonas Inodora grows up to 20 inches in height making it a great cut flower and is often also used for dried flower arrangements. Plant spacing should be 12 - 16 inches apart. Sow Ageratum at 3 -4 seeds per plant and keep moist until germination. Our seeds are always Non-GMO and packaged for the current year.