Q How deep must I plant my bulbs? GLORIA DAVIES, CARDIFF

A The general rule with bulbs is to plant them so the top of the bulb is two to three times the height of the bulb below the soil surface. Bulbs can adjust their height, over time, so it’s not too critical, provided you stick to this rule. However, you can plant tulips much deeper if they’re going into a bed that’s often cultivated, to stop them being accidentally damaged. Deep planting also tends to prevent them breaking up into small, non-flowering bulbs.