Home-grown mustard packs a lot more zest. Seeds chosen for zip, productivity are available now to home gardeners

Two of the better-known mustards in this world are Grey Poupon and Coleman's. The former, if you pay much credence to TV advertising, is a glove-compartment feature of every Rolls-Royce, while the latter carried Jeremiah and James Coleman's name to the farthest corners of the British Empire and beyond and made them very rich men in the process. But good as these two mustards are, they don't come close to the home-grown, freshly ground product. That is the opinion (which I now share) of Rob Johnstone, a mustard lover from his youth and founder of Johnny's Selected Seeds on the outskirts of this rural Maine town.

It so happened that Johnstone and I returned on the same plane from a recent seed conference in St. Louis, and he made his mustard claim just as we were being served sandwiches somewhere over Indiana. With an unbecoming impertinence I said that I'd drop by for lunch sometime to test out his theory for myself.

One week later I did just that, and I cannot recall when I agreed with anyone about anything quite so readily. Home-grown mustard is too good a thing to pass up. Moreover, a little mustard goes a long way. You can grow in a few square feet all the mustard your family can eat. So you might bear this in mind when planning next season's garden. For that matter it wouldn't take much land to grow enough mustard to provide for a small cottage industry.

Johnstone did a good deal of traveling looking for the mustards that would add just the right zest to an American meal. He finally tested two varieties that met his criteria -- flavor, zip, and productivity in the back garden. His winners are the yellow-seeded Tilney, which the Coleman family made so famous, and the brown-seeded Burgonde. Tilney is the variety that goes into yellow American hot dog mustards and the much hotter English and German white mustards. Burgonde is the favorite of many French m ustardmakers.

Johnstone's tests show that mustards (related to but not the same as the mustard greens grown for their edible leaves) are easily grown in well-composted garden soil. Sow in the spring arround the last frost date in rows 12 to 24 inches apart. Sow 8 to 12 seeds a foot and thin after germination to 11/2 to 2 inches apart. The seedlings will survive a light frost.

After three months, when the plants have browned off, cut the plants at the base and stack them to dry. When fully dry the pods can be removed and threshed by rubbing the pods on a flat surface or by bagging the plants and then beating or walking on them. The seeds easily release from the brittle pods. Clean by winnowing and store in a cool dry place.

You can expect about an ounce of seeds per foot of row, or anywhere from 3 to 8 pounds per acre. If that doesn't sound like much, remember an ounce of mustard seed can spark up an individual's meals all month long. So zesty is a good hot mustard that most folks take more of it than they need for a meal. It is said, in fact, that the Colemans grew rich not so much on how much mustard people ate but rather on the excess they invariably had to leave on their plates.

Johnny's Selected Seeds (Albion, Maine 04910) is the only retail seed operation I know selling mustard seed to the home gardener. The company's catalog includes tips on cultivating and preparation, as well as recipes.