Owners of small "commercial" greenhouses are alert for ways to save labor and stretch their producing areas. Both ends can be served by starting annuals ( plants) and tender perennials in flats in late winter or early spring, and moving them to cold frames as soon as freezing - weather is past. Once the flats are moved out, the greenhouse space can be filled with other things.
Selling plants in flats of a dozen to 100 or more avoids the work of potting. Most small plants retail at about 50 to 60 cents per dozen, with the possible exception of double petunias, which usually run to twice that much. Potted singly, these same plants retail for 25 to 39 cents apiece, but to rate that price range the potted plants
will also have to be grown a bit larger than is necessary in flats.
Grow the plants in full sun in a cool house, to keep them bushy. The following are four of the most popular plants small greenhouse owners have found to be steady, profitable items. The cultural hints I offer are, of course, based on the timing of the seasons, weather, etc., in my area. Be sure you take your own local conditions into consideration in applying my recommendations (or anyone's) as to seeding time,etc.
AlyssumAlthough sweet alyssum (Lobularia maritima) is a tender perennial, it is treated in the north as an annual. It can be started in the 50-degree greenhouse. January seed-planting should assure salable plants in April. Culture approximates that of ageratum, and the sweet alyssum can be propagated by cuttings and rooted in any growing media. If your greenhouse is crowded, move the flats of sweet alyssum to the cold frame as soon as danger of freezing is over.
ImpatiensImpatiens - often called patience, busy Lizzie, or touch-me-not - has a translucent stem. Leaves are green, reddish, or variegated green and white. These attractive little plants produce gay flowers of white, pink, red, or purple.
Any friable soil, in 65-degree temperature, is well adapted to impatiens. Seed
culture is much like that of coleus, and you can grow impatiens from seed to bloom in 6 months. Cuttings taken in January and rooted in any media will be ready for 2- or 3-inch pots by April.
Thrips and aphids are the most bothersome pests and can easily be destroyed by malathion.
MarigoldThe brilliantly colored marigolds that grace nearly every garden can become a source of profit for the home greenhouse grower. Sow the seed in ordinary soil in late February. Pot up as growth indicates, and you will have salable plants by mid-May. If you want the extra greenhouse space, transfer the marigold flats to a cold frame or lath house once the danger of frost is over. In this way, they occupy space for only 6 to 8 weeks. A few more weeks in the cold frame and they are ready to be sold in the same flats they were grown in.
PetuniasPetunias are among the best spring sellers. Hybridizers have done so much work on breeding diverse varieties that it is difficult to recognize the old petunia form in some of the new double beauties. Grow your petunias from the best seed you can obtain; it costs very little more than inferior seed and assures you petunias different enough to sell at a premium to gardeners in your community or to a retailer.
Sow petunia seed in mid-January for flowering
by the first week in May. Transplant the seedlings to flats of average greenhouse soil, spacing them about 2 inches apart. They can be grown on and sold directly from these flats; or, as they crowd one another, you can pot some of them in 2- or 3-inch pots.
Petunias do well in 65 to 75 degrees F. and can stand full sunlight. If you are short of greenhouse room, shift your petunias to the cold frame as soon as hard frost no longer threatens.
Aphids are their worst trouble, but in this case, too, malathion makes short work of the pests.
Enjoy growing and selling these delightful plants!
Source : Articlebase
Author :
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A greenhouse is a place made of plastic or glass to trap the energy of the sun and grow various kinds of plants in that place. In order to build a good enough greenhouse you are going to need some important stuff. The aim is to build a place to nurture those plants which cannot grow in colder climates. This place should be such that the plants can get adequate ventilation, warmth and humidity so that they can grow in a healthy manner. Since the greenhouse is an intensive system you would want to grow as many fruits and vegetables possible in that place. Otherwise it will simply not be a cost effective system.
People think that as they depend only on sun rays to give warmth to their plants and do not need an alternative system of heating, no more equipment is required. There are a lot of utilities that are needed to maintain a good greenhouse. The most important of all is a good ventilation system. If on some days the sun is hot, the plants will receive too much heat and they will suffer. On the other hand, if it’s a cloudy day the plants will not be able to receive adequate sunlight and they will again suffer. The ventilation system if good can help tide over this problem. The cheapest way would be to go there and open the doors and windows on a hot day.
It is essential for you to decide how you would want your plants to grow. They can be grown on the ground and also on benches. The best place to grow plants is on the ground but as you grow them year after year in the same place the soil will lose its nutrient content and the risk of diseases to plants also goes up. You can either replace the soil annually or use commercial potting compost. The latter is a better bet as it is very easy to handle compared to the former. Changing whole of the soil is not going to be an easy task.
If you are in a position to spend some extra bucks then you can get an automatic system installed. There are various varieties in automated ventilation system also. It can be a complex involving fans and a simple one in which it controls the opening of windows. The trigger for working is the temperature in the greenhouse. Having a good watering system in place is also very important for the health of plants. You can water the plants by carrying a can of water or have an elaborate system of maybe drip irrigation in the greenhouse. 
A proper lighting system is also essential in it. It will help in extending the growing season for you. Get an electrician to get the fittings done so that power can reach the greenhouse. A properly planned greenhouse will delight many especially if the gardener has limited mobility in the greenhouse. Having benches can be useful. They help in freeing up space for re potting plants and mixing of compost. A path of well laid stones can have the fairy tale effect on the greenhouse
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