The other day I received the following question on wild mustard which I am attempting to answer.
Hi! my name is Jeff and I am hoping that you will help me out. I live in the country where wild mustard is very abundant and recently became curious about harvesting and making my own mustard. I have searched different sites and read much material about wild mustard. The problem I am having is that even though the sites are quite informative I am unable to find any information on when to harvest the plant. Are there different times to pick different parts of the plant for different uses? Case in point, which part do I use and when do I harvest it for making plane old mustard? Do you have a recipe that is exceptionally good for mustard? If you would help me with this dilemma I would very much appreciate it. Thank you! Jeff
Wild mustard while common over most of the United States is not all the same. First, much of the wild mustard is Brissica rapa which is a good edible plant. The leaves, flowers and roots should all be picked in the spring to early summer when they are still young and tender.
Where I live in Northern California, you also have Brassica nigra growing wild which produces a black seed. Mustard plants produce three different types of seeds, depending on the species, white, brown or black seeds. The darker the seed color the spicier the mustard.
If you want to make a dry powdered mustard from the seeds it is fairly easy. During the summer you will see seed pods start to grow on the plants. They will be a couple of inches in length, when you see them start to turn brown pick them. Set the pods where they can dry and they will split open giving you the seeds. A pod can contain 10-18 seeds each and a large wild mustard plant can product 2000-3500 seeds per plant.
The dried seeds once ground in a food mill, will give you “Dry Mustard” just like the powdered mustard you buy in the store. You can add water, vinegar or other liquids depending on your taste. The colder the liquid you add the stronger the bite of the mustard will be. I recommend you mix the powder in small patches, because it can start to lose its bite in a few days. You can also use whole mustard seeds for flavoring in pickles, salad dressings and mayonnaise.
If your primary purpose is to make mustard, I recommend you get one of the strains that produce a known seed. You can even mix the different color seed to control the bite of your mustard.
Here is a link to a prior post I made on wild mustard that will give you information on identifying the plants. Eating Wild Mustard