Short Tutorial on How to Divide Bulbs and Corms

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Master Gardener’s Guide to Storing Seeds for Next Season’s Harvest

As a gardener, there’s something deeply rewarding about harvesting seeds from your own garden and using them to grow next year’s crop. Not only does it save money—avoiding those $1.50 to $7 per packet costs—but it also allows you to preserve the unique characteristics of the plants you love. Whether you’re saving seeds from cherished heirloom tomatoes, vibrant nasturtiums, or your favorite melons, proper seed storage is key to ensuring they remain viable for the next growing season. Here's how to do it right.

1. Start with the Right Seeds

When choosing seeds, opt for heirloom or open-pollinated varieties. These types of seeds will produce plants true to type, meaning the plants you grow next year will be just like the ones you enjoyed this season. Hybrid seeds, while intriguing, may not yield the same results as the parent plant, leading to surprises in your garden. While hybrids can be fun to experiment with, they are less reliable if consistency is your goal.

2. Harvest Seeds at Peak Maturity

Timing is everything when it comes to harvesting seeds. Allow seeds to fully mature on the plant before collecting them. For fruits like tomatoes and cucumbers, this means letting the fruit overripen. For flowers, wait until the seed pods are completely dry.

For example, with tomatoes and cucumbers, scoop out the seeds along with the surrounding gel and place them in a jar with distilled water. Allow this mixture to sit for several days to break down the gel coating—a natural germination inhibitor. Once the gel has separated, rinse the seeds thoroughly and spread them out to dry.

For beans and peas, let the pods dry on the plant. Once they’re fully dry, remove the seeds from the pods. For flowers like nasturtiums or marigolds, wait until the seed heads are dry, then gently shake or rub out the seeds. Some hardy annuals, like sesame, will self-sow if left alone—just step on the seeds to help them settle into the soil.

3. Clean and Dry the Seeds Thoroughly

Cleaning and drying seeds properly is crucial to prevent mold and pests during storage. After harvesting, remove any debris, dirt, or leftover plant material. Dry your seeds completely by spreading them in a single layer on a paper towel, screen, or tray. Place them in a warm, dry spot with good air circulation. Depending on the seed type, drying can take a few days to several weeks. I recommend using glassine envelopes for storage; they are air and water-resistant, providing better protection than paper envelopes, which can wick moisture. Clearly label each envelope with the seed type and harvest date, and consider adding planting instructions. A gardening journal is invaluable for keeping track of these details.

4. Store Seeds in Optimal Conditions

To maintain seed viability, store your seeds in a cool, dry, and dark environment. Ideally, temperatures should be below 40°F (4°C) with low humidity. Here are a few storage tips:

• Use airtight containers like glass jars, plastic vials, or resealable bags. Make sure there’s enough space for your seeds and a silica gel packet or two to absorb excess moisture.
• A small packet of silica gel or powdered milk wrapped in tissue can help maintain dryness in the container.
• If you have the space, storing seeds in the freezer can significantly extend their viability.
• Check your containers periodically to ensure the silica gel packets are still active—most will change color when they need replacing.

5. Test Seed Viability Before Planting

Before you start planting next season, test your seeds to ensure they’re still viable. Place a few seeds on a damp paper towel, roll it up, and put it in a plastic bag. Keep it in a warm spot and check after a few days to see if they’ve sprouted. If most seeds germinate, you’re good to go.

6. Preparing Seeds for Planting

When it’s time to plant, let your seeds come to room temperature before opening their containers. This prevents condensation from forming on the seeds as they warm up. Follow the specific planting instructions for each seed type, and get ready to enjoy the fruits (and vegetables) of your labor.

This past season, I saved seeds from a particularly delicious watermelon I purchased at the grocery store (organic, of course). After rinsing the seeds, I planted them immediately, and five out of six seeds sprouted. Now, I’m eagerly waiting to see if they’ll grow true to type or offer a surprise! Other seeds I’ve collected will wait until the cooler months before finding their way into the soil. Happy gardening!