I don't think petite is a height so much as a body shape. I have seen tall women shopping in the petite section because they have a short waist or shorter arms or wanted a skirt that fits them better than the regular ones, and I have seen smaller women shopping in the junior/misses/womens section for similar reasons.
Sweet clover needs a high pH, 6.0 or higher, for proper nodulation to occur, and it has a higher calcium requirement as well. Sweet clover is able to obtain phosphorus from relatively unavailable soil phosphates and will grow on soils where alfalfa, red clover or ladino will fail.
Test the pH of your soil. Use litmus paper or another testing kit to determine how acidic or neutral your soil is. Onions need a pH range of 6 to 7.5 in order to grow. 1  Drop the pH by digging in manure or compost.  Raise the pH by adding ground agricultural lime into the soil.