Possible Clues:

• Cooking ingredient for cauldron a daughter omitted, sadly
• Ground powder in a bloomer, did you say?
• Thickening agent in cooking
• Sauce thickener
• Sauce ingredient regularly ran, if stored in shade
• Milled grain for a bloomer, say
• Thickening agent
• Cooking thickener
• Surprise new flower heard by thick sort in the kitchen
• It's 18 down till all is blue, by the sound of it