Triumph: Medium height and mid-season blooming in a large selection of colors, make these tulips one of the most popular varieties. They have a strong stem which holds up well under windy conditions. Their height makes them an excellent choice for indoor forcing as well as cut flowers. When to plant your tulip bulbs for a colorful garden next spring: Plant bulbs from October to December; Tulip bulbs can actually be planted up until Christmas and still flower perfectly well in the following spring because they only need a short season of growth.