While it’s certainly possible to simply grab a few packets of flower seeds off the nursery rack, toss them into the dirt, water, and hope for the best, it’s better to consider a few variables when choosing seeds.

Garden flowers that can be grown from seed generally fall into two categories: annuals or perennials.

Annuals: These are plants that sprout, grow, bloom, and die within one growing season. Some of the most popular garden flowers are in this category, including marigold, zinnia, impatiens, and snapdragon. While you’ll only get one season of color from these flowers, they bloom fairly quickly — some within just a few weeks of planting — and provide a glorious burst of color right up until cold weather sets in. Note that in the mildest winter climates, some annual flowers do survive through the winter to bloom again the following year. In most areas, though, you’ll need to replant them each year.

Perennials: These are plants that grow slowly and usually don’t flower until their second year, but they come back year after year, so there’s no need to replant them each season. Often, they die down to the ground during the winter and then reemerge in the spring. Popular perennial garden flowers include aster, coreopsis, gaillardia, bee balm, and morning glory. Many gardeners in cold-winter climates prefer to treat perennials like annuals, however, replanting them each season.

The U.S. Department of Agriculture established the Plant Hardiness Zone Map back in the 1960s, with many updates over the years. The map divides the United States into 12 zones based on average low winter temperature, with the higher-numbered zones having the mildest winters. Every package of perennial seeds, and most annuals, indicates which garden zones are best suited to the particular flower, but take heart: you can grow perennials outside their preferred zone, but consider them annuals.

Consider where you’ll be planting your flower seeds and the effect you desire. If you want a hanging basket exploding with beautiful blossoms, you’ll want trailing flowers such as petunia, portulaca, lobelia, vinca, and sweet alyssum. The same flowers work well if your goal is to cover a small patch of ground. Other garden flowers with upright growth patterns, including popular choices like cosmos, zinnia, sunflower, celosia, and marigold, are perfect for garden beds or growing in containers.

Every seed package indicates whether the flowers do best in full sun, part sun, part shade, or full shade. Generally, that breaks down as the following:

• Full sun is a minimum of 6 hours of direct sunlight each day.
• Part sun and part shade both mean between 3 and 6 hours of sunlight each day, with part shade toward the lower end of that range and part sun toward the higher end.
• Full shade doesn’t mean the flowers can do without any sun exposure at all but that they can tolerate a little less than 3 hours of direct sunlight each day, with mostly dappled sunlight during the remainder of the daylight hours.

You won’t go broke buying flower seeds, which are far more economical than buying nursery starts, 4-inch pots, or gallon containers.

As a general rule, a packet of flower seeds costs between $2 and $3. Depending on seed size, you’ll get 10 to 100 seeds for that price. You can also find larger seed packets, meant for covering large stretches of ground, for anywhere between $5 and $15, depending on the mix of seeds and the brand.

Compare that to a six-pack of nursery starts, which generally costs $2 to $5, a 4-inch single plant, which will run you the same, or a gallon nursery container, which typically sells for $5 to $10 and holds just one plant, although it’s admittedly a well-established and already flowering one.

Before purchasing a packet of flower seeds, take the time to read all the fine print. Here’s the information most often provided.

• Photo: Every packet of flower seeds has a lovely picture of the blooming beauties on the front.
• Name: Most seed companies list the common name and the specific variety over the flower’s photo, along with info on the color. For example, a packet might read “Zinnia, California Giant, Mixed Colors.” Some companies add the botanical name of the flower on the packet’s front, while others state it on the back.
• Brief description: You’ll typically find a couple of sentences describing the flower, along with any special characteristics such as scent, appeal to butterflies or hummingbirds, or drought tolerance. Many companies also include information on flower size, growing the plant in a container, and growth habits here as well.
• Planting time: Every packet of seeds indicates the best time of year to plant the seeds in your particular area.
• Bloom time: This refers to the time of year you can expect flowers. For many annuals, that’s spring right up until the first frost.
• Light requirements: Here’s the information on how much sunlight the plant requires for optimal growth. Plant full-sun seeds in a shaded area and you will get fewer or perhaps no blossoms.
• Days to germination: This tells you how many days or weeks before you can expect to see shoots appear above the soil.
• Days to bloom: Some companies include information on how many weeks or months until you’ll enjoy actual blossoms.
• Growing height and spread: This is the average height and width of the mature plant.
• Planting directions: Here, you’ll find instructions on how deeply to plant the seeds and how far apart to space them. Note that if you’re planting the flowers in a container rather than into a garden bed, you should space them around half the recommended distance apart for a more bountiful container. Some flowers have other special instructions, such as to soak the seeds before planting them.
• Packed-for year: Both flower and vegetable seeds are packed fresh for each year’s growing season. While you can certainly plant seeds beyond that year, fewer of them will germinate.

Q. Can’t I just harvest seeds from my garden instead of buying seeds?
A. Sometimes. While you often can successfully harvest seeds from your existing garden, if those flowers are a hybridized variety — very common in the gardening world — you might find that planting their seeds leads to flowers that are not quite the same as their parents. Remember as well that to gather flower seeds, you’ll need to leave the blooms in place as they wither and dry. This might not be a big deal in a large flower bed, but it isn’t desirable in a container garden or hanging basket.

Q. What about vegetable seeds?
A. There’s nothing quite like the taste of vegetables grown by you and harvested fresh from your very own backyard. Most of the information given here with regard to choosing flower seeds also applies to vegetables, although you’ll need to follow the seed packet directions more carefully to produce the biggest crop of veggies.

Q. Why do my flower seeds die shortly after sprouting?
A. It’s an unfortunately common scenario: you’re excited to see your seeds sprout and start to grow, but then they collapse and die. While a variety of factors can cause this, the most common is a fungal disease called damping off. Damping off usually strikes when the soil stays too wet and isn’t in a spot with good air circulation. You can’t save seedlings with damping off, but you can help stave off the condition by not overwatering your seedlings, planting them in a spot where the air circulates, not ignoring the sun requirements of the flower, and thinning the seedlings so they aren’t too crowded.