Planting Seeds in Spring – Butterfly Lady

Most native milkweed seeds and many native flower seeds need cold moist stratification to germinate successfully. After the recommended days of cold moist stratification are done, you can direct sow the seeds outside in the spring after the last frost under a very light amount of soil or you can start them in containers with soil.

The last frost date for an area is the day a region usually has its last frost. You can type in the phrase “last frost date by zip” and discover sites where you can find the last frost date for your specific zip code. You can also click here to find out the last frost date for your area: https://mygardenlife.com/frost-map-with-dates

Below are ten steps to starting seeds indoor (or outdoors) in containers.

Step 1: Prepare the Seed-starting Soil Mix

You need a seed starting mix for germinating seeds in containers. It’s possible to make your own seed starting mix or purchase a commercially prepared seed soil mix. The soil should be sterile to decrease the risk of bacteria interrupting your germinating rates. I recommend using a soil mix that contains mycorrhizae which helps the roots absorb nutrients and helps prevent fungus.

Soil mix that contains **mycorrhizae** helps to promote root growth, increase nutrient and water uptake, and helps grow larger plants.

Step 2: Dampen Seed Mix and Plant the Seeds

Put the soil mix into a bucket and put water into it and mix it well. You do not want it to be too wet but wet enough to keep seeds moist. I recommend pots, cups, or containers that are at least 4 inches deep to accommodate root growth. You can also purchase seed trays. Sow the seeds by scattering them on the soil surface 1/4 inch apart, and then lightly cover with additional soil mix, coconut coir, or peat moss. Gently mist the surface with water to dampen the additional soil mix that has been added.

Step 3: Cover for Humidity

Covering the seeds will protect them, maintain moisture levels, and create the perfect environment for those seeds to get a great start. Covering the seeds increases the humidity, which is essential for high germination rates. Cover the pots with clear plastic wrap or a plastic dome that fits over the seed-starting tray. This creates a greenhouse effect and speeds germination. I make my own seed tray by using the aluminum baking trays with plastic covers that I purchase at the dollar stores.

You can purchase commercially made seed starting trays or make your own from aluminum baking pans. Rotisserie chicken or salad containers can be used to make mini greenhouse to start seeds.

Step 4: Keep the Seeds Warm

Once temperatures reach over 75 degrees Fahrenheit (24 degrees Celsius) outdoors the germination process will begin. For indoor growing the temperature should be kept around 75-80 degrees F (24-27 degrees C) for optimal growth. If starting the seeds inside place the containers near a window. You can use grow lights to keep the seeds warm, and some gardeners prefer to use heat mats especially designed for seed trays.

If starting seeds indoors, I place the seed trays on heating mats in front of a window.

Step 5: Keep Soil Moist.

After you dampen the seed starting mix when planting the seeds, use a spray bottle or misting hose to keep the soil evenly moistened. Most seeds fail to germinate because the seeds are allowed to dry out.

Step 6: Uncover the Seedlings Once They Germinate

Seeds will typically germinate in 7-20 days. Once they germinate you can remove the cover. It’s very important to uncover the seedlings and expose them to light once they germinate, otherwise they will rapidly become straggly, with overly long, thin stems.

Once the seeds start to germinate remove the lid to allow air flow.

Step 7: Transplant the Seedlings to Individual Pots

Once seedlings have grown a few pairs of “true leaves” and are big enough to handle without damage, they can be transplanted into larger individual pots with potting soil. Be sure to fill the cups almost to the top to give the roots plenty of room to grow.

These Arizona milkweed (Asclepias angustifolia) seedlings are ready to be transplanted into individual containers because they have developed true leaves (second set that follows first cotyledon leaves). Click here to learn how difference between a seedling’s cotyledon and true leaves, and how you can use the leaves to tell when the plant is ready to be transplanted.

Step 8: Keep Transplanted Seedlings Out of Direct Sunlight While They Establish Roots

If seedlings are placed outside, keep them out of direct sunlight (but not in a dark or overly shaded spot) for a week until the roots grow into the new soil and have a better chance of absorbing moisture. In dull, overcast weather, you don’t need to do this.

These Aquatic milkweed (Asclepius perennis) seedlings have been transplanted into larger cups and placed on a shelf on the porch outside.

Step 9: Harden Off Seedings

If plants have been grown inside need to be “hardened off” or slowly acclimated to the outdoors over a period of about seven to 10 days. Gradually introduce them to direct sunlight, dry air, and cold nights so that they don’t suffer shock from the sudden change in growing conditions.

Step 10: Plant Young Plants

Once plants have reached the stage where their roots are starting to emerge from the bottom of the pot, they can be planted out to their final location in your garden.

You can protect the young milkweed plants by covering them with wire basket purchased at dollar stores.

Diagnosing Seedling Problems

Leggy seedlings are the result of insufficient light after germination.
Solution: Move seedlings grown indoors as close as possible to a window as soon as they sprout.

Seedlings that are shriveled or toppled over is seen in cold, wet conditions that cause a damping off disease. Pathogens kill or weaken seeds pre-germination (or shortly afterwards).
Solution: Try to provide adequate light, heat and ventilation and avoid overwatering.