Spring is nigh and it’s definitely time to think about starting some seeds indoors for planting outside when the weather is warmer.

If you haven’t yet started onion or celery seeds, now is the time to get going with those. Later in the month, start seedlings of broccoli, cabbage, cauliflower, lettuce, spinach and many different flowers.

Wondering what to start when? For a handy interactive chart, see https://tinyurl.com/y8oufb45. Here, you can input the average last spring frost for your area and the chart will advise when to start the seeds indoors. To discover the average frost-free date for your area, go here: https://tinyurl.com/y8xjkzbl.

Although seeds have different ideal starting dates, most of them have the same general requirements. First off, you want to start the seeds in a sterile soilless potting mix. Garden soil is too heavy and too full of potentially damaging bacteria to be used for seed starting indoors. Use clean containers with good drainage. You can use peat pots, plastic cell packs, wooden or plastic flats, plastic produce containers or any similar item.

Different seeds germinate at different temperatures. This site, https://tomclothier.hort.net/page11.html, lists the effect of soil temperature on germination rates of a variety of vegetable seedlings. For instance, spinach germinates in only 12 days at 50 degrees but it takes 23 days for seeds to sprout at 41 degrees. However, you get more plants at the lower temperature with a 96 percent germination rate at the lower, slower temperature as compared with 91 percent in the warmer zone.

While spinach likes it cool, you can see that most of the seeds prefer warmer soil temperatures. Using a heated mat designed specifically for gardening can provide that extra amount of warmth. Although not cheap, my mats have lasted me for decades.

Some seeds prefer to germinate in the dark while others demand light. Read the seed packets carefully for each type you grow. In general, if the seed is planted with only a minimal layer of soil on top, it probably needs extra light.

While a sunny window may be good enough to get seeds to germinate, it is not sufficient to get healthy stocky seedlings. For that, you will need supplemental lights. I am still using fluorescent fixtures, those 4-foot shop lights that used to be available everywhere. These days, LED lights are more common but pricier. Whichever type you choose, make sure that the bulbs are providing adequate light. As the fluorescent bulbs age, they get dark on the ends and although they still emit light, it is not really enough.

Because artificial light is no match for the natural light in a garden, it’s usually best to put the lights very close to the garden seeds, usually within a couple of inches. Placing the lights too far above the seedlings can lead to tall and spindly plants. Note that lights this close can generate heat so pay attention daily to make sure the plants aren’t drying out. Imitate the outdoor conditions and set the lights on a timer to provide eight hours of darkness every day. I keep my heat mats hooked up to the timer too so the seeds get a cool down in the evening.

Keep the seedling soil moist but not wet. It’s better to be a bit too dry than too wet. Again, a daily check is probably necessary and it is also fun. When the plants have at least one set of true leaves, not just the cotyledons, it’s time to pot them up into larger containers.

Beverly Carney can be reached at cultivating country@gmail.com.