Fruits
- Strawberries are an extremely popular greenhouse fruit and the berries grown in your greenhouse will taste much better than those sold in a supermarket. The protected greenhouse environment means your strawberries will suffer less from disease, pests, and marauding animals. Strawberries flower and fruit between 35°F to 85°F, so they can produce beautiful fruit year-round as long as your greenhouse maintains that range.
- Cantaloupe are great even for small greenhouses, where you can grow them on a trellis, but you may want to introduce some bees to help with pollination or sit down and engage in some manual assistance. If you’re using a trellis, you can support the growing fruit in a string net to help support the weight as it grows. Melons you grow yourself can be harvested later than commercial melons, meaning they’ll have more time to produce natural sugars and will taste sweeter and richer.
- Chilies are so valuable for their ability to boost flavor in even the most mundane dishes, but they’re also packed with nutrition. Chilies do best with a long and hot growing period, so they are ideal for greenhouse conditions. Chilies require at least 6 hours of sunlight each day, so keep that in mind if you decide to sow seeds early either in a warm greenhouse or indoors. If you’re a fan of intense flavor and really hot chilies, give them time to turn red before you harvest them.
Herbs
- Cilantro is actually a cool season crop that prefers temperatures between 50°F and 85°F. When temperatures move higher, the plant will bolt. The leaves don’t have much flavor at this point, so it’s best to let the flowers go to seed and collect them to plant for your next batch. Cilantro should not be transplanted, making it a great candidate for pots. It grows quickly, and while it can produce for many weeks, it’s a good idea to sow a new batch every two to three weeks to keep supplies fresh. You can extend your season by starting seeds early in your greenhouse, moving the pots indoors during the hottest months, then moving them back to the greenhouse to continue producing.
- Thyme is easy to grow from seed where a consistent temperature of 70°F is ideal. Your warm greenhouse is perfect, although if your cold greenhouse isn’t quite there yet, you can start your seeds inside. Thyme is a hardy perennial, so once it’s established, it will overwinter happily even in a cold greenhouse.
- Bay Laurel is a small, aromatic evergreen tree that thrives in a container and housed in a greenhouse. Individual bay leaves can be simply picked as required - the biggest and oldest leaves have the strongest flavor.
- Rosemary is an attractive, extremely fragrant evergreen woody herb that is available in upright or creeping varieties. Rosemary can be used in landscaping, or it can be kept in pots for easy access to the kitchen. Rosemary is very forgiving and can tolerate greenhouse temperatures up to 120°F and down to 10-20°F, making it an ideal plant to propagate and grow in either cold or hot greenhouses.
- Basil is a warm season herb that responds well to growing in pots and under the controlled conditions of a greenhouse. Keep the temperature at least 50°F, but don’t move it indoors since basil needs 6 to 8 hours of full sun every day. Basil is most productive in temperatures ranging from 80°F to 90°F, but there should be a distinct fluctuation between day and night temperatures for healthy growth. Preferred nighttime temperatures are in the range of 65°F to 72°F
Choosing Seeds
- When you’re choosing your seeds it’s easy to be overwhelmed by the profusion of seed catalogs, but don’t let that slow you down. The freshest, most popular seeds are typically purchased in the fall for spring planting, and if you wait until it’s time to start, many of your preferred options will be sold out.
- Look for seeds with a guaranteed freshness date - seeds that are more than a year old might still sprout, but why chance it?
- Consider the available seed types such as heirloom, hybrids, and GMO
- Heirloom seeds are seeds that are produced from plant varieties that were around before World War II. They are open pollinators, meaning they’re naturally pollinated by insects, wind, birds, or human hands. They reliably reproduce seeds that will grow into the same variety as the parent plant. These varieties have stood the test of time, but they have not been artificially improved through hybridization and genetic modifications. This is a great option for adventurous gardeners who prefer to produce their own seeds, free of the vagaries of market availability.
- Hybrid seeds are selective crosses between two different varieties, producing a plant with the best qualities of both parents. Hybrids are the favorite seeds to sell in your local garden shop since they produce plants which are resistant to disease and reliable in their production and maturity dates. Since hybrids are produced only through artificial pollination, their seeds do not reproduce true to the original plant. In other words, you may still get a tomato, but it won’t be the same “Better Boy” hybrid you grew last year. Hybrids are great options for new gardeners and those who are comfortable with purchasing new seeds every year.
- GMO seeds are produced in a laboratory where gene splicing produces plants not available in nature with specific characteristics that make them resistant to certain pesticides, herbicides and viruses. They can be engineered to be more drought and frost tolerant, resistant to poor quality soils, and to produce higher crop yields. Currently, the only GMO seeds in the US are for commercial production crops such as corn, soybeans, alfalfa, and sugar beets. You’ll see many seeds in your local store marked as “non-GMO,” but genetically modified seeds are actually not available to the public, so there’s no need to be concerned at this point.
If your concern is for long-term independence from unstable prices and availability for your home produce, heirloom seeds are the way to go. Many fans say the flavors and textures of heirloom produce are superior, but keep in mind that they tend to be more prone to physical defects and diseases. You may also need to change your idea of what color a carrot should be.
