UNITED STATES—Local retail nurseries can sell more varieties of more types of plants than anyone needs. That which is unavailable from one nursery is likely available from another. That which is unavailable from any local nursery might not perform well locally. There really should be no need for catalog or online shopping. Of course, many garden enthusiasts would differ.

Catalog shopping, whether from a printed catalog or online, affords many more options. Such catalogs are from specialty nurseries that specialize in particular plants. They lack in selection of different types of plants but excel at their particular specialties. Therefore, they can sell more varieties of their type of plant. They do not need to stay open all year.

Exline Iris Garden, for example, grows and sells only iris. Their catalog features nothing else. However, it does feature 1,231 cultivars of iris! Most retail nurseries that market iris cannot provide one percent of that. Exline Iris Garden accepts orders only from January to early September. Such orders go out for delivery only from July until early September.

Catalog shopping has certain limitations.

This delivery date range conforms to the dormancy cycles of the iris rhizomes. Similarly, delivery of bare root fruit trees and roses occurs only during bare root season. Delivery of bulbs also happens while such bulbs are dormant. Some plants, particularly evergreens, can be ready for delivery at any time of year. Their roots may be contained in potting soil.

Other restrictions may apply. Some plants are unavailable for import into California from other states. They may have potential to become invasive or transmit disease. Citrus, for example, can transmit disease. Therefore, it is unavailable for import. Some plants might be dissatisfied with local climates. Peonies are not recommended locally for that reason.

Seed has fewer, if any restrictions. Most is clean so that it should not transmit disease. Seed for the most invasive plants is mostly unavailable. Seed are much less perishable than other plant items, which facilitates delivery. Each seed catalog features more variety than any garden can accommodate. Nowadays, almost every print catalog is also online.

Highlight: Zinnia

Extensive breeding complicates the identity of modern garden zinnias. Although they are products of several species, most identify simply as Zinnia elegans. They exhibit a broad range of floral color and form. Short varieties grow only a few inches tall. Large varieties grow as tall as two and a half feet. They are warm season annuals that bloom until frost.

The two- to four-inch-wide flowers bloom in phases as long as the weather is warm. Their floral color can be yellow, orange, red, purple, pink, salmon, chartreuse or bronze. Some varieties have striped or freckled flowers. Some resemble daisies, with big petals around prominent centers. Pom-pom types produce puffier flowers with nearly obscured centers.

Zinnias enjoy good exposure and rich soil. The paired and very slightly raspy leaves can be susceptible to powdery mildew. Removal of deteriorating flowers promotes continual bloom. However, a few can remain to produce seed for the following season. Their seed should be sown as soon as possible after the last frost. Zinnias are excellent cut flowers and can last for a week or even two.

Contact Tony Tomeo at tonytomeo.com.