Just do this:
I can promise you, the plants will grow and grow non stop! I have cut mine down maybe 10-12 times, but they still grow out.
Its important that you plant spring onions from your own country! If not, you can destroy your garden, food production and the envioroment.
I live in Norway, and the temperatures during summer is around 15-25 degrees C, and my spring onions love this temperature. Remember to keep the soil moist. They need a daily dose of water. In the winter you can take your spring onions inside.
Its possible to plant sugar peas, salat and other plants with roots in the same procedure. But not every plant is easy to grow, and need more help with growing.