Calendula Oils, Vinegar and Other Uses

Could you please inform on the best oil, if there is one, to infuse marigold (calendula officinalis) flowers. And do you recommend the use of heat or to simply let the flowers infuse at room temperature, and for how many days or weeks?? Thanks so much for your help.

I have not infused calendula in oil. When I do make herb oils, I like to use sunflower or canola oil. I half fill a clean jar with the chopped herb (flower petals in this case), pour in fresh room temperature oil and cover. The I refrigerate and let it infuse. You can check it for flavour in about a week. If you like the taste, strain out the flowers and store in refrigerator up to 6 months. If you want the taste more intense, leave another week. If after that time it is not getting stronger, then strain out petals and add fresh petals. Oils can go rancid at room temperatures that is why they should be refrigerated.
You might also like to try this method. Place flower petals in food processor, with machine running, pour in oil through feed tube. Store in refrigerator and use within I week. Or, strain and refrigerate up to 6 months. I have read that you can also heat the oil, pour over the herbs (flowers) a let steep for about an hour. Strain and store in refrigerator. So, try them out and see what give you the best results/flavour.
I have made flower vinegars. I use white wine vinegar, either room temperature or heated (not boiling). Allow to infuse for about a week (if heated, check after 2 days). Strain out flowers and store at room temperature in a dark place or dark bottle.
Also try infusing the petals in warmed honey (to add to tea), or to jams and jellies (added at end before pouring into jars).
Use oils and vinegars to make salad dressing, mayonnaise, marinades. Toss oil with croutons for soup or salads, marinate cheeses, drizzle over tomatoes (fresh or broiled), fry eggs, drizzle over garlic before roasting (after cutting off top of garlic head), drizzle over pizza or vegetables, or to finish a soup, etc.