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).
The first sign that it is the proper planting time for tomatoes is when the night time temperature stays consistently above 50 F./10 C. Tomato plants will not set fruit until the night time temperature reaches 55 F./10 C., so planting tomato plants when the night time temperature is at 50 F./10 C. will give them enough time to mature a bit before ...