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Cultivars for hobby Greenhouse Production

Posted by Jim Brown, Horticulturist on 7/16/2007

YOU FINALLY HAVE YOUR OWN GREENHOUSE and it’s up and operational. The next decision, if you have not already determined this, is what to grow in your new greenhouse. The answer depends upon your purpose for having the greenhouse as well as some other factors. If part of your purpose for getting a greenhouse is to provide at least some of your own food, you will need to start by allocating space for those types of plants. Growers quickly find that their greenhouse is smaller than they realized once plants are in and growing.

Most any plant will grow in the greenhouse. Every plant requires its own space; some plants require more space than other plants and still others need the space for a longer time. Some plants, like tomato, will take space in the greenhouse for a long time but will produce over much of that time. Other plants, like lettuce, will take space for six to eight weeks and the whole plant will be removed when it is harvested. The novice grower should take some time to plan out his plant layout for the greenhouse to avoid overcrowded conditions as plants grow.

Once you have decided what you will grow, the next question is do you grow your own plants from seed or buy plants that are already started? Although it seems easier to buy plants that are already started, it will actually save you much trouble to start all your greenhouse plants from seed. Bringing in started plants like tomatoes, peppers, cucumbers, or lettuce from a nursery or another greenhouse is asking for disease and insect problems, because both diseases and insects can travel into your greenhouse on your nursery-bought plants.

With a little planning and scheduling you can have your own plant starts when you need them. However, some plants are not commonly started from seeds. If you want to grow some of these plants, starting everything from seed may not be a workable plan for you. In those instances make sure you purchase your plants from a reputable greenhouse, and keep those plants segregated from the rest of your greenhouse plants until you have had a chance to observe them for a few days.

Make sure you start with good-quality, fresh seed such as our tomato seeds for sale. If you’re interested in growing your own organic produce, organic seed of some types of cultivars are available. Although true organic seeds are not available for many cultivars, most seed producers are no longer treating their seeds with fungicides. This usually allows the seeds to be used for certified organic production if organic seeds are not available.

SEEDS FOR GREENHOUSE FRUIT-BEARING PLANTS

Before we proceed to discuss specific cultivars, let us talk a bit about the seeds. Greenhouse cultivars of tomatoes, peppers, and cucumbers are grown form seeds that are F1 Hybrids. They have been developed through a breeding program that has many advantages and only a few disadvantages.

The fruit characteristics like taste, size, and keeping quality are selected in the breeding process. Resistance or tolerance to various fungi, viruses, and bacterial diseases are also characteristics that are selectively bred into greenhouse cultivars. Because greenhouse cultivars are kept in production for longer periods of time than outside cultivars, disease resistance is more important in them than in their outdoor counterparts. It is important to keep the plant healthy and productive for the longer period of time during which they are grown in the greenhouse.

Conversely, cultivars bred for outdoor production will have different characteristics than those bred for greenhouse production. Different things will be more important to the growth, development, and production of the outdoor plant compared to one in the greenhouse. Because of these distinct differences cultivars bred for greenhouse production will do a better job in the greenhouse than cultivars bred for outside production.

Seeds from a plant grown from F1 hybrid seeds should not be saved for planting. Because of the way F1 hybrids are developed and produced they will not come true to the F1 seed that was initially planted to create the parent plant. In other words, a seed saved from a fruit from an F1 hybrid will have a different mix of genetic material than its parent had.

Tomatoes, peppers, and melons that you purchase in the grocery store are usually the fruit of F1 hybrids developed for field or greenhouse production. Seed from such fruit will not produce plants that produce fruit similar to what you purchased.

Purchasing the seed of greenhouse cultivars for production in your greenhouse will give you much better results and will be well worth the cost of the seed.

Heirloom cultivars are not F1 hybrids. They can be and are reproduced by saving and planting the seed from the fruit of the plant. They are generally old cultivars that have been passed down for many years. Although heirlooms can be grown in the greenhouse, they present some problems. They have very little disease resistance compared to the greenhouse cultivars. They cannot be depended upon to provide an extended productive life in the greenhouse. The plants will need to be replaced in the greenhouse two to three times as often as plants of greenhouse hybrids. Commercial growers who grow heirlooms have them grafted onto a rootstock that gives the plant more vigor and some disease resistance.

GREENHOUSE FRUIT-BEARING PLANT CULTIVARS

Now we’re ready to discuss specific cultivars. Greenhouse tomato seeds are generally grown from F1 seeds. Beefsteak cultivars include Blitz F1, Match F1, Matrix F1, Geronimo F1, and Trust F1. These cultivars produce large tomatoes in the half-pound range.

Cluster or truss tomatoes are four or five ounces in weight and grow with three to seven fruit attached to the truss. They keep for a fairly long time and have a little tougher skin than do beefsteak tomato fruit. Cultivars include Tradero F1, Clarance F1, and Ambiance F1.

If you are interested in small tomato cultivars, Dasher F1 is a grape tomato and Flavorita F1 and Conchita F1 are cherry tomatoes.

Greenhouse cucumbers are seedless F1 hybrids. The seeds in the fruit produced are not developed and are not viable. The only way to get seeds for a seedless cucumber cultivar is to purchase the F1 seeds from the seed producer or a distributor.

There are a variety of popular cucumber cultivars, each of which can be grown at a different time of the year. Accolade F1 is a European-type cucumber cultivar that will grow during the time of year when there are lower light levels. It is not tolerant to powdery mildew and, therefore, should not be grown during the summer when mildew spores are more prevalent. Camaro F1 is a newer cultivar that will grow well in the low light period of the year and has partial powdery mildew tolerance so that it can be grown during the summer as well. Discover F1 is a powdery mildew-tolerant cultivar that should not be grown through the low light period.

Mini cucumbers are seedless but more the size of the traditional garden cucumber. Manar F1 is a powdery mildew-tolerant cultivar that should not be grown through the low light period. Jawell F1 is a newer cultivar that is partially powdery mildew-tolerant and can be grown through the summer as well as low light periods.

Moving on to pepper plants, most any cultivar of hot pepper can be grown in the greenhouse fairly easily. Bell peppers grown in the greenhouse, however, will require a little more attention and manipulation of the fertilizer program to achieve success. Greenhouse cultivars of bell peppers are now available, although just a few years ago, selections of field cultivars were used in the greenhouse for bell pepper production. Since then, a number of bell pepper cultivars have been developed in various colours. There are, however, no green pepper cultivars. Green bell peppers are picked from red or yellow bell pepper plants before they ripen. A bell pepper fruit, unlike a tomato fruit, will not ripen or continue to ripen once it has been removed from the plant.

Red bell pepper cultivars include Cubico F1 and Hawaii F1. Kelvin F1 and Lesley F1 are yellow cultivars and Paramo F1 is orange. These cultivars have all been bred and selected for greenhouse production.

Eggplant and okra can be grown in the greenhouse. They will both produce fruit over a period of time once they start fruiting. Neither crop is a big greenhouse commercial crop in the United States. Although some greenhouse Eggplant cultivars have been developed, you may want to try your favourite garden cultivar first. No specially adapted okra greenhouse cultivars, however, have been developed for greenhouse production.

Squash of the yellow straight neck and zucchini types can be grown in the greenhouse. The typical field cultivar is a bush plant that will produce over a short period of time. A few new cultivars that will produce over a longer period of time in the greenhouse have been developed, but seeds for them can be difficult to obtain. In a squash plant the main stem of the plant continues to grow for an extended period of time. Fruit continues to be produced as the main stem grows, but be aware of the space needs of this plant when planning your greenhouse plant layout.

GREENHOUSE VEGETATIVE PLANTS

Lettuce, basil, Swiss chard and most other herbs are grown for their foliage — or vegetation — and not for the fruit that they may bear. As such, they are known as vegetative plants. They are harvested while they are still in the vegetative plant growth stage. The F1 hybrid breeding program is usually not used to develop cultivars of this type of plant.

When most people grow lettuces in the greenhouse, they grow bibb or other types of leaf lettuce. With these types of lettuces, the entire plant is edible. Growers can begin to harvest and consume the lettuce even at an immature stage so that one planting can be used over a period of time. Most growers will seed lettuce every week or so to have different-stage lettuce plants in the greenhouse at all times.

Bibb lettuce cultivars are developed in Europe and are developed for greenhouse production. The cost of the seed is high compared to garden lettuce seed, but it offers the disease resistance and other characteristics that make it well adapted to the greenhouse environment. A selection of cultivars is available. Some do better during the cooler winter weather while others like more light and are resistant to bolting and tip burn. Rex is a tip burn and bolt- resistant cultivar that does well in the summer. Hawaii and Natalia are a couple newer cultivars for the spring, summer and fall time period. They have more disease resistance than do some of the older cultivars.

Some Grand Rapids-type leaf lettuces perform well in the greenhouses. Although the leaf lettuces have been developed for outdoor growth and production, some of the cultivars are well suited for greenhouse production. Their suitability has been determined by trial-and-error methods by greenhouse growers and seed providers. In Johnny’s Seeds Catalog, the lettuce cultivars that have done well in the greenhouse are identified. In this group, Black Seeded Simpson, Waldamann’s Dark Green, and Two Star are included.

Newer red lettuce cultivars have been doing fairly well in the greenhouse the last few years. Cultivars in the Lollo Rossa and Redina groups generally grow well and develop fairly good red colour if the light levels are adequate. Dark Lollo Rossa is one cultivar available from Johnny’s.

Romaine or cos lettuces present more of a challenge to greenhouse growers in the summer. Many cultivars will tip-burn fairly readily during the summer in the greenhouse. Johnny’s Green Forest is one cultivar that has been grown successfully by many greenhouse growers all year long.

Most herbs can be grown fairly successfully in the greenhouse. Most are grown from seed, but a few need to be grown from cuttings. The herbs grown from seed do not have special cultivars for greenhouse cultivation.

Edible flowers can be grown in the greenhouse if you are interested in having them available to adorn salads and other dishes. No special cultivars are used for them. Any pansy or nasturtium cultivar can be used to provide a number of fresh blossoms over a period of time.

Choosing the right type of cultivar or combination of cultivars can have a profound impact on the outcome of your greenhouse production experience. There is not one right answer for everyone. Hopefully, you can use the information provided above to reach your production objective.

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