Gifford Garden Notes
Caring for your seedlings
by Diane Fagergren
After you have sown your seeds and placed them in a warm, well-lit place, the watching and waiting begins. Check your containers everyday to see if germination has occurred. Once you see the tiny sprouts breaking through the seed coat, take the cover off and allow the light and air to circulate around the new plant. If the cover remains on after the seedling emerges, it will stretch and the stems shall become weak.
As this tiny embryo starts to grow, a plumule or shoot emerges. Then two seed leaves called cotyledons unfold. A root called a radicle starts to delve downward. Nutrients contained within the seed, in the endosperm, feed the seedling until its first true set of leaves appear. Once the seedlings have their true leaves, you should start to feed them with a seed starting fertilizer (like 9-45-15) at half the normal dose. Follow the directions on the package. Over fertilizing can cause damage too, so use caution.
Now that the true leaves have developed, the seedlings will need to go into a larger container to accommodate its growing root system. This process of gently teasing the seedlings apart is called pricking off.
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Carefully pull the seedlings apart and always be sure to hold them by the cotyledons. The stem contains very important vascular systems that can be easily damaged so, I repeat, hold the seedlings by the leaves only! After you have successfully separated them, plant them into their new container.
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It is important to water the newly transplanted seedlings thoroughly so that the water reaches the bottom of the container. This will encourage good root development. Place your plants in a warm, well-lit location. It is a good practice to cover seedlings that have just been pricked off with a single layer of newspaper for the first day. This will shelter them from strong sunlight and be less stressful on the seedlings. Once these plants get established and put on some new growth, it will be time to move them outside. To acclimate them to the outdoors, place them in a sheltered location on an overcast day or in an area that has dappled sunlight. This will help prevent sun and wind burn. A cold frame is perfect for hardening off seedlings. Make sure to place a shade cloth over the frame during the day so that the seedlings can get accustomed to the sun's strong rays. Vent the cold frame if it is warm out and close it down on chilly nights. When you can see small white roots emerging from the bottom of the container it is time to plant them in the garden. Make sure if you are planting annuals, that it is past the last frost date for your area.
Gifford Garden Archives, January 2003 - present
Gifford Garden Archives, July 2001 - January 2003