A Question of the Week

pumpkin seeds

If you are an avid gardener, at some point in time you’ll likely become interested in saving seeds. People have been saving seeds for thousands of years, preserving some of the seeds of the most productive crops to grow again the following year. Nowadays, seed saving is less common among home gardeners because it is easy to purchase high-quality seeds from dozens of seed companies at low cost. However, with heightened interest in unusual, heirloom and locally adapted vegetable and flower seeds, many devoted gardeners are trying their hand at saving seeds from their own gardens.

In doing this, you get to practice informal plant breeding by choosing to save seeds from plants that have the best traits like fruit quality, yield, maturity date, disease resistance or other qualities. Being a successful seed saver doesn’t require an advanced degree, but it does demand careful planning and a basic understanding of plant reproduction.

Plant Reproduction Basics

At the most basic level, seed production requires the movement of pollen from the male parts of a flower (stamens) to the female parts (pistil), which results in fertilized ovules (seeds). Plants that are the same species will readily pollinate one another, whereas different species will not.

Plants are often broken into two categories by their method of reproduction: self-pollinating and cross-pollinating. Self-pollinating plants have “perfect” flowers that include both male and female parts, and the flowers are often constructed in a way that prevents pollen from other plants from entering. Cross-pollinating crops encourage pollination by other plants of the same species. In many cases, they have developed mechanisms that prevent them from pollinating themselves, such as having separate male and female flowers on the same plant or releasing pollen before the female parts of the flower are receptive to fertilization.

Pollination results in genetic recombination. The seeds of self-pollinating plants will usually grow to closely resemble their parent because there is little novel genetic recombination occurring. However, the offspring of cross-pollinated plants have the potential to display much more diversity.

This comes to a head in the garden when seed savers want to keep seeds of a specific variety of flower or vegetable. Self-pollinating crops, such as peas, beans, tomatoes and peppers, are the easiest to save because it is less likely they will have crossed with other varieties in the garden. It is more difficult to preserve a variety if you are growing cross-pollinating species such as squash or corn. These plants will readily cross with other varieties of the same species, so if you are intent on saving seeds, it may be necessary for you to carefully pollinate flowers by hand or by only growing one variety. Otherwise, the seeds will likely grow into plants that have inferior characteristics.

It is important to note that cross-pollination does not impact the quality of the current crop, which will have all the characteristics of the desired variety regardless of what it was pollinated by. However, the seeds of cross-pollinated plants will often grow into plants with flowers or fruit that are very different from their parent plant. The exception to this is corn, which will have the traits of both parents in the harvest year.

Additionally, none of this comes into play if you are saving seeds from the straight species of a plant, not a variety. While this almost never happens in the vegetable garden, many wildflower seeds can be saved successfully without any thought given to pollination.

Hybrid or Open-Pollinated?

To muddy the waters further, plant varieties can be classified as either hybrid or open-pollinated. Hybrid plants are the result of specific crosses of two different varieties, thus combining the characteristics of both parent plants. Hybrid plants often have superior characteristics such as disease resistance, high productivity and outstanding vigor. However, they are not suitable for seed saving because the seeds collected from hybrids will not resemble their hybrid parents. Instead, they will have a combination of traits from the two, both the good and bad.

If you are really interested in saving seeds, choose open-pollinated varieties. Open-pollinated varieties produce offspring that are very similar to the parent plant as long as they self-pollinate or cross-pollinate with the same variety. Many open-pollinated varieties are “heirlooms” that have historically been passed down through generations.


The next key to successful seed saving is getting the harvest timing right. Different procedures apply whether you are collecting “wet” or “dry” seeds. Plants with wet seeds include tomato, eggplant, cucumber, melon, squash and pumpkin. These seeds need to be harvested when fruit is ripe and then processed to remove wet pulp or gelatinous coatings that surround the seeds. The best way to do this is to scoop the seeds out of fully ripe fruit and put them in a glass jar filled with a little bit of water. Stir the mixture a couple of times a day. The mixture will ferment and viable seeds will sink to the bottom. Finally, pour out the liquid, rinse the seeds and set them out to dry on plates or baking sheets.

Peas and beans should be left on plants until their pods are brown and dry and their seeds are rattling on the inside. Remove the pods from plants and spread them out indoors in a dry place out of direct sunlight. After a couple of weeks, you can shell the pods to extract the seeds.

Many flower and herb seeds can also be collected by waiting until flowers have fully finished blooming and seed heads turn brown. The best protocol varies by species, and it doesn’t hurt to do a little research before harvesting.


After putting lots of effort into collecting your seeds, you’ll need to store them properly. It is essential to keep seeds dry and cool so that they will remain viable until the next spring. Ideally, they should be stored in tightly sealed glass containers. Individual varieties or different types of seeds can be placed inside of paper packets and then packed together inside of a larger glass container. A good temperature range for storage is between 32° and 41°F, making the refrigerator a good place for keeping seeds.

Humidity can sometimes be an issue inside of containers, so adding a desiccant can be helpful. A small amount of silica-gel from a craft supply store or powdered milk wrapped in tissue or cheese cloth will absorb moisture and keep seeds dry.

Finally, make sure to carefully label seeds before you put them into storage. At minimum, note their name, variety and the date you collected them. Aim to use saved seeds within a year, as older seeds do not germinate as well and are not as vigorous.

Got questions? The Ask UNH Extension Infoline offers practical help finding answers for your home, yard, and garden questions. Call toll free at 1-877-398-4769, Monday to Friday, 9 a.m. to 2 p.m., or e-mail us at answers@unh.edu.

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Got questions? The Ask UNH Extension Infoline offers practical help finding answers for your home, yard, and garden questions.
Call toll free at 1-877-398-4769, Monday to Friday, 9 a.m. to 2 p.m., or e-mail us at answers@unh.edu.