Many gardeners start from seed at least some of the plants that will produce food and flowers in their garden. As seedlings grow, sometimes they encounter problems that result from their physical environment. If the problems are promptly and properly diagnosed, damage can be minimized or corrected and the immature plants can be assured their place in the garden, come May.

If tiny seedlings line your windowsills and any other horizontal surface that can support plant trays, cell packs, pots or containers, you may notice that not all of them are doing as well as you’d like. Many problems arise from overcrowding, inadequate sunlight or too much watering. Use the following guidelines to help identify your problem.

Spotty or inconsistent germination: While some species naturally have a low germination rate or germinate unevenly over an extended period, most common garden plants germinate well and relatively quickly. Generally speaking, we can expect at least half of the seeds sown to germinate. While poor germination can result from soil-borne diseases that attack developing seedlings, a common cause is inadequate, inconsistent moisture.

Once seeds are sown and dampened, maintain the moisture level. If the growing medium is allowed to dry out during germination, developing plants may be set back or die. Even before we are able to spot leaves, tender little roots are taking form beneath the soil. If the soil dries too much, these roots wither and fail to gain resources to continue growth by setting on leaves.

. Spindly or leggy plants with fine, fragile stems: Elongation of stems commonly results from inadequate light. Thin, weak stems can also be a symptom of seed sown too densely. Even under a grow light, plants emerging from seeds sown too closely can yield spindly stems as they compete to reach the light source. Two simple solutions: Sow seed at the recommended distance and provide adequate supplemental light. Seedlings will stretch toward the light even in a bright, sunny window. Consider implementing grow lights and don’t be afraid to install them close (12-15 inches) from the tops of your seedlings.

. Light green or yellow seedling leaves: Off-color or yellow leaves may be a sign of poor fertilization. By nature, seeds are packed with all the necessary resources until they produce their first set of true leaves. As seedlings emerge, you will see one or two leaves. Most seedlings do not require additional fertilization until their next set of leaves (the true leaves) form. Fertilize seedlings with a balanced fertilizer at half strength for two weeks.

For example, if using a soluble, synthetic 20-20-20 fertilizer, mix at a rate of 11/2teaspoons per gallon of water. Allow the mix to dry slightly, not completely, between waterings.

. Seedlings that topple over at the soil line and stems that are brown and withered: Root- or stem-rotting disease afflicts vulnerable seedlings. Perhaps the most common disease is damping off, which is evident when seedling stems become weak and brown and collapse at the soil line. Damping off is a fungal disease, which is minimized through proper watering. Overwatering and a cool growing environment often exacerbate disease problems. When damping off is spotted, the prompt eradication of affected seedlings and the soil around their root zones may be an effective control measure. Often widespread damage is uncontrollable. Reseeding in clean growing mix is the best defense against the disease.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, RR1, Box 2120, Montville 04941, or e-mail them to dianagc@ctel.net. Selected questions will be answered in future columns. Include name, address and telephone number.