Here is a video of the engine. There are marks on the ball to make it's rotation easier to see. You will notice that at the start I hold the ping-pong ball in my hand very briefly so the liquid nitrogen will boil and start the rotation quickly.
They can be planted in the spring around your last frost date. Gladioli bloom about 90 days (three months) after they sprout in spring, so the bloom time really depends on when you plant them. In warm climates, where they stay in the ground year-round, gladioli bloom anytime from late spring (deep South) to midsummer (middle South).
Now is also a good time to plant 5-gallon citrus. Water deeply once this month. April Remove any citrus you did not eat, since they fall from the tree. If you still have grapefruit on the tree, you might decide not to pick them up, they keep on getting sweeter until the summer. It is still a good time to plant citrus. Check that all the trunk parts of citrus and young trees that are exposed to the sun are painted white. This keeps them cooler and protects them from sunburn. Use white latex paint diluted with water (1 volume white flat latex paint for 1 volume water).