It depends on the person as far as you need to dig to plant your flowers. It depends on how deep the hole is and how far you want to plant the product as well.
You should plant it 15 inches apart.
You should plant them 3 inches apart.
You should plant them arond 3-4m apart
15cm should be fine
the ground.
Plant the bulbs in clusters of 5-7 bulbs 4" apart at irregular intervals, about 4" deep in good fertile soil.
A plant's roots go as deep as the C Horizon.
Rows should be spaced 12" apart and the seeds within the rows should be planted 3" apart. Once the plants are growing, transplant the seedlings, making sure each plant has 6" of space on both sides.
As far as "it" goes
Tulip bulbs should be planted about 6 to 8 inches deep in the soil.
When planting a daffodil bulb, you have to find a site with full sun or part shade with somewhat fertile and well-drained soil. Plant the bulbs in the fall about 3-6 inches apart. Bear in mind that they will soon be crowding each other. Generally planting is done in the fall, but late winter is OK, too, as long as the ground is not frozen. The bulbs need to be 2 times as deep as the bulb is high. A 2-inch long bulb should be planted 4-inches deep. If the winters are severe, 3-inches of soil above the bulb tip is recommended. In clay soils, don't plant as deeply as in sandy soil. If planted too deeply, the bulb will produce long stems and few flowers.