Vigorous Hybrids

Photo: Scott Robinson

The first generation offspring often not only have the parents' good qualities, but actually perform even better.

A hybrid plant is a cross between two different varieties.

Nature has produced hybrids for thousands of years; in fact, most traditional garden plants emerged by hybridization long ago, either by chance or with help from attentive farmers. However, at garden shops, plants labeled as hybrids are usually just the first generation offspring of two carefully selected parents. Here’s why.

Plant breeders observed long ago that when you cross two parent plants with desirable traits, something strange happens. The first generation offspring often not only have the parents’ good qualities, but actually perform even better. This phenomenon is called hybrid vigor.

How does it work? Scientists disagree on exactly why first generation hybrids perform so well, but it has something to do with the benefits of genetic mixing.

Most species, including humans, carry some defective genes. However, many defective genes never influence the individual’s development, because when there’s a second, good copy of the same gene, the good copy activates instead. Inbreeding increases the chance of inheriting two defective copies of the same gene, but hybridization does the opposite.

First generation hybrid plants have two different copies of each gene, one from each parent. That means there’s a better chance there will be at least one good copy, and helps explain why first generation hybrids are vigorous all around!