Many of us start gardening, at least as adults, by purchasing a few plants from the garden center, big box store, or those temporary greenhouses that spring up in supermarket parking lots in spring. We come home with a four-pack of petunias, a couple of tomato plants, or a hanging basket. Buying potted plants and plunking them in a spot in the ground is convenient, but the price for convenience is high. 

As our gardening ambitions grow, we may wish to save money by starting our own plants, desire a wider selection of varieties, or want to grow vegetables and flowers not typically available in garden centers. At that point, we begin experimenting with planting seeds.

The rewards of planting seeds are many, but significant savings often rank near the top for gardeners. I regularly plant more than 50 tomato plants each summer. Buying them all as transplants would cost several hundred dollars. Instead, I start them all from seed for about ten bucks in seed and potting mix, plus a little TLC. 

Here are a few pointers to help you get started on the right path growing a garden from seed.

Choosing appropriate varieties

At the garden center or supermarket, the selection is limited, especially for annuals. You may find five varieties of tomato, one or two types of summer squash, or three varieties of hot peppers. Take a quick look through a seed catalog and you’ll see what seems to be an endless selection to choose from. Where to start?

While seed companies strive to carry seed from good varieties, not every variety is a good match for your location, growing season, or uses. If you have a small backyard plot, Hubbard squash may not be a good fit space-wise. If your spring weather is short and shifts quickly to summer heat, a bolt-resistant lettuce is a better choice to extend your harvest. Check out our recent article about How to Read a Seed Catalog for some helpful hints when perusing the selections.

Choose varieties that match your growing season, are sized appropriately for your space, and factor in climate considerations like cool nights, extreme heat, or short growing seasons. For example, a patio planter on your deck will probably do better with a determinate tomato. If you’d like to have a tomato plant spill over the sides, crawl up the railing, and take up a lot of space on your deck, then by all means, go for the indeterminate varieties. And of course, choose varieties that intrigue you! That’s part of the fun.

How many seeds to sow

Just as you might determine how many tomato plants to purchase at the garden center based on your available space, do the same when starting them from seed. However, when starting from seed, you'll plant a few extra. 

We plant more seeds than we need plants because not every seed will germinate, although most should. A few seedlings may die after sprouting, and a few may be less vigorous. I typically sow or start about twice as many seeds as I want plants, whether starting them indoors or out in the garden. It’s like insurance. If everything comes up healthy and vigorous, you can simply thin out extra seedlings. For young potted plants, it’s easy enough to find good homes for them. 

You’ll need an early start

Gardeners accustomed to buying plants from the greenhouse may be shocked by how much more time it takes to start a garden from seed. Not time on your part, necessarily, although there is a bit of that. But time for the plant to germinate and grow. The bushy tomato you purchased in a 12-inch pot has been growing for 8-10 weeks in a greenhouse. The hanging basket full of already-blooming petunias was started by the grower back in January, or even earlier.

Because of this lead time, it’s common for gardeners to start many types of plants indoors while the weather is still too cool to garden outside. Vegetables like tomatoes, peppers, eggplants, and even some cole crops like broccoli, cauliflower, and kale, are often started indoors, then transplanted outside after the weather warms. Some flowers, like snapdragons, statice, and petunias, can also be given a head start by sowing indoors. 

Even vegetables, herbs, and flowers that do well when sown directly in the garden take some time to get rolling. Zinnias do very well when planted straight into the garden soil, but you won’t have flowers right away. Rest assured, they’ll come right along. 

Seed planting timeline terms

Transplanting most vegetables and flowers happens after the last spring frosts are over, so it’s easy to figure out. But seed planting time varies widely.  

Here are a few common seed planting and timing phrases, and what they mean:

Start Seed Indoors: Many flowers and vegetables that either take a while to get going (thus benefiting from a head start) or are finicky about sprouting are recommended for starting indoors. The timeline varies greatly. Typically, timing recommendations are given in terms of the number of weeks before your last spring frost. Look up your average last frost date by your ZIP code here.

As soon as soil can be worked: Many cold season crops like our lettuces, peas, and kale can be sown outdoors quite early. The phrase "as soon as the soil can be worked” in gardening circles generally means that all frost is out of the ground, the soil has drained enough to not be muddy, and daytime temperatures are above freezing, even if there is an occasional overnight frost. It’s probably around a month before your last frost date in spring. 

Direct sow: This one is just as it sounds. Direct sowing means simply planting seeds right into the soil in a garden bed. It’s the simple way to garden, and for many plants it works better than transplanting. Some plants, like carrots, corn, and sunflowers, do much better when direct sown.  

Soil temperature is important

As explained in our article, How Seeds (Actually) Germinate, temperature is important for seed germination. It’s the reason for some of the timing recommendations in the previous section. While every plant has an optimum temperature at which germination is the quickest and most reliable, we don’t need to start spreadsheets and log one-degree fluctuations. There is a general rule that will serve well.

Cool-season crops will germinate in cooler soils. Heat-loving crops need warmer soil temperatures. It kind of makes sense. For example, spinach, lettuce, and peas (cool-season crops) will begin germinating in soil as cool as 40℉, although they germinate faster with soil warmer than 50℉. Tomatoes and peppers, however, are warm-weather crops and often won’t reliably germinate until soil temperatures reach 60-70℉. Even warmer is better. 

If starting seeds indoors, room temperature is fine for most plants, but you’ll get faster germination with warm-weather crops using a heat mat. If you are starting seeds in a cool basement, you may need to provide some warmth. When sowing seeds directly outdoors, remember that planting heat-loving seeds too early can result in slow or no germination, and they may rot before they have a chance to pop up.

Lastly, relax

Sowing seeds outdoors is about as simple as gardening gets, but there are still a few pitfalls to avoid. Check out our article, Improving Seed Germination Outdoors, for some tips to increase your success. 

If you start seeds indoors, eventually you’ll need to transplant them, which is quite similar to transplanting potted plants from the garden center. For some transplanting tips, including how to harden off seedlings, check out our transplanting guide. 

Whether planting indoors or outdoors, seed packets include specific instructions on spacing and depth, usually printed on the back. If the packet is illegible (which happens after they get a bit damp) or you don’t have the original, remember the general rule: small seeds are planted shallow; larger seeds, deeper. 

Remember to have fun. Seeds want to germinate, given moisture, temperature, and oxygen. You can always buy a few plants to fill in any holes, or resow the row again if germination was spotty.