A Garden Jump Start: Tips for Being Your Own Nursery

Starting seeds indoors is as much about fun as it is practicality, warding off winter blues while saving money.

Most any plant can be started indoors and transplanted when the timing is right. Katvic/Shutterstock

One of the biggest benefits of starting seeds indoors is the selection; one is no longer limited to the varieties found at local nurseries and home and garden stores. Most any plant can be started indoors and transplanted when the timing is right.

All this selection isn’t necessarily a good thing; seeds need to be chosen judiciously. For example, northern gardeners with shorter growing seasons should focus on quicker harvest times. A good example is snap beans, which can mature in as few as 50 days, versus pole beans, some of which can take up to 110 days.

Another consideration is the growing space (i.e., determinate tomatoes for a small garden or container as opposed to indeterminate tomatoes, which sprawl). While you’re at it, purchase some easy-to-grow marigolds, nasturtiums, or sunflowers (dwarf for a small space) to attract pollinators.

The Importance of Timing

Ordering seeds early is the key to getting the best selection, but that doesn’t mean that they should be planted the minute they arrive. While most plants should be sprouted two to eight weeks before they should be planted outdoors, there are exceptions, such as petunias, which may need up to 10 weeks, or pansies and violets, which require up to 14 weeks. In contrast, zinnias usually need only four weeks. The trick is to count backward from the date that they can be planted outdoors.

Cool-weather crops such as broccoli, cauliflower, kale, lettuce, and spinach can be planted before the last frost date, when the nighttime lows reach 40 degrees Fahrenheit, as long as the soil temperature is at least 70 degrees F. Some can handle even lower temperatures, but remember that the ground must be workable, not frozen. On the other hand, warm-weather crops such as tomatoes, peppers, and eggplants won’t do well under 50 degrees F. Planting them out early won’t give them a head start; at best, they’ll remain semi-dormant, while the worst-case scenario is that the low temperatures may kill them.

Additional Head Start

One way around the timing restriction, if there’s sufficient light and space indoors, is to pot up the plants indoors from their initial starter trays or cups to the next larger pot size, or the one after that. Tomatoes are an excellent example, with most green-thumbed gardeners starting them in four- or six-cell starter trays. These seedlings can be potted up to a four- or six-inch pot once they are 3 inches tall and have a few sets of true leaves (the first leaves that don’t look like all those that come after them are called “seed leaves”).

To get even more of a head start, these plants can be potted up a second time into a 1-gallon pot, which promotes deeper root growth and allows a near-mature plant to be set out in the garden after hardening off (slowly exposing them to chilly temperatures and direct sunlight in increasing increments before planting in the ground).

A combination of fluorescent and natural lights is usually best for plants. EvgeniusD/Shutterstock

Growing Bright

While, for centuries, home gardeners have been starting seedlings indoors with a window and small pot, why not take advantage of the latest technology, starting with proper lighting?

Most plant varieties will grow stronger and faster under fluorescent lights—even simple, standard cool white tubes—compared to natural indoor light alone. A combination of fluorescent and natural light is best, but fluorescent alone will do if necessary. Hang the lights on chains that can be raised as the seedlings grow. Ideally, lights should be suspended 2 inches above growing plants, with a 4-inch maximum. These limits are to help the plants grow compactly. Seedlings that don’t get sufficient light will develop long, skinny, weak stems as they stretch toward an alternate light source. Invest in an inexpensive timer, as most seedlings are happiest with 12 hours to 16 hours of light daily and a dark period each night.

Professional grow lights can be expensive, but they offer the benefit of being designed to provide the specific light ranges required by plants. These can range from individual bulbs or standalone grow light fixtures to complete grow light systems with built-in sprouting/growing trays that are attractive enough to be placed in the living room for a dash of living greenery to counteract the gray outdoors.

Note: Seeds that require darkness to germinate should be moved into the light as soon as they sprout.

Hot Tip

The right temperatures are necessary for proper germination and growth. If the room is already in the 70-degree F to 86-degree F range that most seeds prefer for germination, that’s good. If not, consider using a heating mat. Once the seeds have sprouted, lower the temperature by about 10 degrees for happy growth. While heating mats come with a thermostat, to get a true idea of what is happening in each pot or tray, invest in a soil thermometer. Seedlings can become leggy and weak when they receive too much heat.

Food and Water

Once light and warmth are adjusted properly, watering, humidity, and fertilization are additional key factors to take into account for optimal seedling health.

Spa-Like Setting

Seeds need to remain moist in order to germinate. Too much water can lead to rot, while too little can cause seeds to dry out, losing viability. Mist each newly planted seed tray with water, then cover it with either plastic wrap, a plastic bag, or specially made plexiglass or plastic covers to retain moisture.

Ready, Set, Sprouted

Immediately remove the covering as soon as the seeds germinate, unless it is a specially designed vented cover that is left on. Check the plant babies regularly, and water when the soil surface is dry to the touch.

Feed Them Right

Many commercial potting mixes contain a slow-release fertilizer that will see seedlings through their initial growth and even a potting-up or two. Otherwise, apply a diluted liquid fertilizer every two weeks, following the package directions.