A stock plant is a plant which is used for propagation. There are a number of ways to utilize stock plants, depending on the plant being grown. Nurseries usually maintain a large library of stock plants which they use to cultivate plants for their customers, as do commercial growers of flowers and crops. Stock plants are sometimes known as “mother plants,” referencing their important role in the process of plant propagation.
One of the simplest uses of a stock plant is in propagation by seed. In this case, seeds are collected from the stock plant to ensure that high quality plants which are true to the cultivar will be produced from the seeds. Stock plants can also be used as a source of cuttings for propagation, along with a source of grafts, bulbs, and other vegetative matter which can be used for propagation. Asexual plant propagation is often used to control quality and outcome, with exemplars of a desired cultivar being cloned over and over again to produce plants for sale.
In order to be used as a stock plant, a plant needs to possess certain traits. From a horticultural perspective, it needs to be a proved and reliable performer which is of high quality. It also needs to be free of disease; if a stock plant becomes diseased, all of the plants propagated from it can potentially have the disease as well. Healthy stock is especially critical in agriculture, where cuttings from a diseased plant could cause an infection to destroy an entire crop.
Home gardeners may use stock to propagate plants for their gardens and those of friends. They should take care to use healthy plants of high quality, and to maintain stock plants in healthy, controlled conditions to avoid the introduction of plant diseases and pests which could spread to other plants. It is also a good idea to inspect any plants, seeds, cuttings, and so forth cultivated from a stock plant and given away to confirm that they are healthy.
The term “stock plant” is also used sometimes to refer to rootstock. Rootstock is a system of hardy roots and a partial trunk to which another plant or tree can be grafted. Viticulturists often use rootstock to grow delicate grapes in harsh climates, relying on the robust nature of the rootstock to support the plant. Rootstock is also used for growing many tree fruits such as apples and peaches.