These bulbs, colchicums and fall-blooming crocus, extend your growing season, but you may want to tap into a sense of urgency about nabbing these bulbs before summer's end. Although these bulbs are from different genera, they confusingly have similar common names — both are often known as "autumn crocus." And just to add a bit more confusion, both colchicum and true crocus are technically not grown from bulbs, but from corms. Fall-blooming species of true crocus include showy crocus (Crocus speciosus), hairy crocus (Crocus pulchellus), and saffron crocus (Crocus sativus), while the majority of colchicums are fall-blooming, including the popular Colchicum autumnale and Colchicum 'Waterlily'. Low availability may also be linked to limited use in gardens since they're planted long before most fall bulbs are.