Home gardeners looking for inexpensive herb seed are in luck, as many varieties are not only cheap, they replace themselves over time. Popular herbs and culinary herbs are often the least expensive option because there is a larger market for them. Obtaining specialty herb seeds may require placing an order through a greenhouse, catalog or online retailer. Shipping and fees add to the slightly higher cost of these seeds.
Seed Number and Size
Basil and dill are among the least expensive seeds available. Part of the reason for this is that these seeds are larger and easier to harvest. A single plant can produce a generous number of seeds, which can then be saved for planting the following year. Basil and dill are annuals and more expensive in the long run if you don't save seed. Saving seed serves to decrease the overall cost because a single purchase can potentially provide you with a free supply of seed for the next growing season.
Herbs that are perennial, generally hardy and tolerant of a range of conditions are less expensive. Perennials--like mint, oregano, sage and chives--are less expensive because they can produce both plants and seeds. Mint is perennial, even invasive. Sage will return, but tends to thrive less with each season. The ability of the plant to persist and return the following growing season means fewer seeds to buy and greater return on your investment.
Hardy and Tolerant Varieties
The ease with which the seed can be saved and started is also a factor. Some varieties may be difficult to start from seed. Ginseng, for example, is more expensive because it is difficult to grow and seeds are not usually gathered until the plant is several years old. Some seeds also remain viable longer in storage. The biennial parsley is considered a medium-lived seed with a storage potential up to three years.
Herbs that produce large seeds and heavy producers--plants that yield large numbers of seeds--are often the least expensive seeds, simply because their seeds are the most readily available. As seed size shrinks, the individual seeds become more difficult to harvest successfully. Many are lost to handling and in transit, in packaging and planting. Smaller seeds are also difficult for the home gardener to separate and plant at the proper distance and depth. Their size makes them tough to manage. The fewer grown, the less seed, the greater the cost of obtaining a seed.
Other factors that can increase the price of seed include whether it has been treated, if it was organically grown and if it is from an heirloom variety. Heirloom seeds are somewhat rare and difficult to grow. People are willing to pay more for them because the plants produced are more flavorful, more aromatic, have unique characteristics, produce consistent to parent plants and have good natural resistance or ability to grow in a particular climate. Heirlooms that cross-pollinate require special handling to preserve genetic purity. This labor and trouble adds to the final cost.