Growing Leafy Greens From Seed

Lettuce, kale, spinach, chard, arugula, mustards and even herbs. When you think about “salad” today it’s usually a beautiful medley of colours, sizes and textures containing many varieties of leafy plants. Gardeners refer to this group of crops simply as “greens” – even if they have many different and distinct characteristics and uses beyond a salad mix. Greens can be eaten raw and fresh, but some can also be sautéed, stewed or even grilled. While the list of these plants is long, the difficulty of growing them is extremely low. In fact, if there is one thing that every beginner gardener should start with, it’s growing greens. And one of the best features of growing greens is their productivity and ease when starting them from seed. So much so, that you can grow multiple successions of them each year!

Here is a guide on growing beautiful, healthy, bountiful greens.

When to Grow

Greens are a quick-growing crop that love the cooler weather of spring and fall. They do best when the days are warm and nights are cool, particularly daytime highs in the 16-21°C (60-70°F) range. To get a head start in early spring, or to continue growing them later in fall, consider a cold frame or simple poly tunnel to act as an temporary greenhouse. Fall is an underrated gardening season and the plants that are grown in fall tend to be easier to manage than spring-sown greens. Fewer insects, not as much watering, less weeds and the fact that the plants will stay alive even as the temperatures get close to or below freezing, allow you to keep enjoying them far longer.  

Leafy greens grown in warm weather are easily stressed and this causes them to "bolt" or flower prematurely. Some heat-tolerant varieties of greens can hold up to summer temperatures, otherwise considering interplanting leafy greens in shadier parts of the garden (between taller plants or in areas that don't get full sun). You can also use shade cloth to protect them from direct sun if you want to grow them all summer long.

Where to Grow

Greens don't need deep soil to grow well, making them very versatile for many types of gardens. They grow wonderfully in traditionally sprawling in-ground gardens, as well in organized and protected raised beds, but can just as easily be grown in pots and containers on spaces as small as a balcony or rooftop. No matter the location, they prefer airy, loamy soil high in organic matter such as compost or manure. Most greens are great companions plants and because of their limited space requirements they can be scattered around and between other plants. Growing greens with beans and garlic is especially beneficial. Beans help fix nitrogen to the soil which encourages leaf grow, and the smell of garlic helps to repel slugs and snails from eating your greens.

Starting Seeds

Seeds can be started indoors or outdoors in trays, or in the soil directly. If using trays and you plan on transplanting later, sprinkle seeds in rows as close as 2 inches apart and cover with ½ inch of soil before watering in well. I prefer to overseed and thin out plants every 2 inches. When sowing directly into the garden, you can overseed and thin out or space plants and rows 8 inches apart. If starting inside, place trays under grow lights or next to a south or west facing window. When starting them outside, consider a location that gets at least 6 hours of sun, but a little shade will help keep the soil temperature just right. In either case, ensure the soil stays moist through germination in 5-10 days. 

Spring greens can be sown directly in the soil as soon as it is workable. If starting indoors or under a protective cover, they can be done two weeks earlier and then planted outside once nighttime temperatures are consistently above freezing. Once leafy greens are growing consistently they can be reseeded every few weeks for a continuous harvest. To grow them in the fall months, work back from your typical first frost date and start seeds 7-8 weeks before that to ensure plants are in the garden and growing for at least 5-6 weeks to get them to full size by the time the season starts to slow down.

How to Care For Greens

With a shallow root system, the most important factor in caring for greens is to keep the soil sufficiently moist. Not only does this ensure great growth rates and production, it keeps the plants from getting stressed due to fluctuating temperatures, too much sun, or other environmental conditions. Greens also benefit from boosts of nitrogen. Organic fertilizers like blood meal and liquid seaweed emulsions are good options. For an easy DIY compost tea let a few handfuls of green grass clippings sit in a bucket of water for 3-5 days, then dilute  half-and-half with water to feed your plants. Watch this "how to fertilize greens" video here. 

Harvesting Greens

Depending on the variety, greens reach maturity in 40 to 70 days, but can be eaten as small as a few inches (baby greens). Clippings from overseeded trays that are thinned out can go right into salad mixes. As plants get larger, it’s best to harvest the outer leaves only as you need them – this keeps the rest of the plant growing and gives inner leaves a chance to mature. This is the time to start the next round of seeds for replanting. Once full heads of greens start to overcrowd and touch each other you can cut them down entirely to enjoy – making room for new transplants in their place. 

Buying Seeds vs. Saving Seeds

In order to grow successions of beautiful greens, you will need to get your hands on reliable, high-quality seeds. Initially, you may want to shop around for packets of various varieties to start on your own. You can find seeds online, at big-box stores or at nurseries almost all year round. There are countless seed suppliers and types of lettuce, spinach, kale, etc., so read the packet carefully for what grows best in your growing zone, garden conditions and for your tastes. Even with repeated over-seeding and thinning out, a single packet of seeds can last years. The only drawback in starting from purchased seeds is one of the most frustrating things a gardener can face: low or no germination. It’s an unfortunate reality that some packets can be duds – though most companies will offer and honor a satisfaction guarantee. So, if you prefer you can buy spring nursery transplants to eat and for seed collection. Since greens are so easy to start and grow quickly, I wouldn’t recommend buying seedlings regularly, but by purchasing them once you can guarantee a crop, try the variety out, and save seeds of your own. 

To collect seeds from greens, let the plant grow past maturity until it flowers, or bolts. Before it does, you can harvest leaves to eat, without cutting the entire plant down. Once the flowers have dried out they will leave behind pods – usually either long or round – full of seeds. You can either store whole pods or loose seeds in a cool, dry, dark place. Hot and dry conditions trigger the plants flowering, so consider saving seeds from the first planting of greens in spring, which will bolt once summer weather rolls in for good, and leaves time for at least one more planting succession in fall. Fair warning: a garden full of overgrown and seeding plants is not the prettiest to look at, but do it once and you will have reliably germinating seeds for life.

Now you know everything there is to starting and growing your own greens! If you need a more detailed approach specific to your garden space I can help create a custom garden plan for you to follow along. Want to know specific tips for particular varieties? Try one of my garden coaching programs where I can answer all your questions and instruct you how to do it for yourself. What greens are you growing or will you try now? Leave a comment below to tell me. 

Buon giardinaggio!