About me: Greenhouse Fruit Production in Southwest Texas
> West Texas above 4,500ft elevation is ideally suited to greenhouse production of many fruits. Summers are cool and dry enough that greenhouse temperatures can be held in the ideal range. Winters are mild enough that heating costs are reasonable. A greenhouse of 1728 sq ft in Alpine, Texas costs about $50 per month for cooling and $300 per year for heating to 39F.
>
> Soil is a very well drained, deep, clay loam with moderate water holding capacity.
>
> Winter chilling requires about 10-12 weeks with nights at 38-40F and days as cool as possible, about 55-60F. Winter chilling is aided by shade cloth and evaporative cooling. The crops requiring most chilling hours are sweet cherries and some apricots. The other fruits discussed need eight weeks of chilling or less.
> Summer cooling is achieved via wet wall and opposing 36 inch exhaust fans. The high temperatures in summer can be held below 95 F in a greenhouse in Alpine.
>
> All greenhouse fruit species listed have been grown both in-ground and in 5-15 gallon pots. Fruit quality can be superb from potted trees but it is more variable and the fruit is smaller. Brix levels listed are for in-ground trees mostly on Citation and Gisela 5 rootstocks spaced from 6ft by 8ft to 4ft by 3ft. Citation is precocious and increases fruit size but is very susceptible to crown gall. Grapes and figs are too vigorous planted in-ground in the greenhouse. Potting makes them much more manageable.
>
> The key management issue for highest fruit eating quality is water. Limiting water enhances both sweetness and flavor. Greenhouse average total water application for fruit is 28 inches per year. This equates to 1.0 inch every 10-21 days from May thru September (via drip) plus 7-8 inches by flooding in the dormant season to leach salts and rewet the soil profile.
>
> The watering regime could be described as deficit irrigation. The idea is to force the plant to adapt to a water deficit in spring and then maintain that deficit all summer. This lowers the water content of fruit and increases sugars, ie brix. The hardest part is the spring transition. Irrigation begins when the shoot tips stop growing. Vegetative growth during summer is slow. The water deficit has been taken too far if the trees begin to drop leaves or the fruit shrivels. This watering regime is suitable for most fruits in the greenhouse because water demand is low but only for the very drought tolerant fruits outdoors in Alpine; mainly grapes, jujube, and figs.
>
> The floor of the greenhouse is covered with Extenday reflective fabric to increase light in the canopy, control weeds, and save water. This in part accounts for low greenhouse water needs. Light in the greenhouse is highly diffused by IRAC poly and ground fabric but is probably only 33-50% total PAR compared to outdoors.
>
> Little or no fertilizer is applied to greenhouse fruits. It's generally not needed since the fruit trees aren't competing with any ground cover vegetation.
>
> Average brix levels have been 18-25 for pluots and nectarines, 24-32 for sweet cherry, and 16-22 for apricots. Fruit size is generally good despite limiting water as much as possible. Flavor King pluot sometimes averages 200 grams and several nectarines 3-4 inches, ~300-450 grams. Fruit size is reduced by greater water deficits. For instance nectarines running ~28 brix at higher water deficits are 50-70% the size of 18-22 brix fruit.
>
> Key pest is spider mites which build up in late May. There are many new miticides available for control.
>
> The authors single most favorite fruit is Honey Royale nectarine for it's sweet and incredibly rich flavor. Other favorites are the other Honey and Arctic series nectarines, Orangered and Robada apricot, Flavor Supreme and Flavor King pluot, Strawberry Verte fig, Sweetcrisp blueberry, and Summer Royal grape. Summer Muscat is a great tasting grape but has small berries and cracks.
>
>
> West Texas above 4,500ft elevation is ideally suited to greenhouse production of many fruits. Summers are cool and dry enough that greenhouse temperatures can be held in the ideal range. Winters are mild enough that heating costs are reasonable. A greenhouse of 1728 sq ft in Alpine, Texas costs about $50 per month for cooling and $300 per year for heating to 39F.
>
> Soil is a very well drained, deep, clay loam with moderate water holding capacity.
>
> Winter chilling requires about 10-12 weeks with nights at 38-40F and days as cool as possible, about 55-60F. Winter chilling is aided by shade cloth and evaporative cooling. The crops requiring most chilling hours are sweet cherries and some apricots. The other fruits discussed need eight weeks of chilling or less.
> Summer cooling is achieved via wet wall and opposing 36 inch exhaust fans. The high temperatures in summer can be held below 95 F in a greenhouse in Alpine.
>
> All greenhouse fruit species listed have been grown both in-ground and in 5-15 gallon pots. Fruit quality can be superb from potted trees but it is more variable and the fruit is smaller. Brix levels listed are for in-ground trees mostly on Citation and Gisela 5 rootstocks spaced from 6ft by 8ft to 4ft by 3ft. Citation is precocious and increases fruit size but is very susceptible to crown gall. Grapes and figs are too vigorous planted in-ground in the greenhouse. Potting makes them much more manageable.
>
> The key management issue for highest fruit eating quality is water. Limiting water enhances both sweetness and flavor. Greenhouse average total water application for fruit is 28 inches per year. This equates to 1.0 inch every 10-21 days from May thru September (via drip) plus 7-8 inches by flooding in the dormant season to leach salts and rewet the soil profile.
>
> The watering regime could be described as deficit irrigation. The idea is to force the plant to adapt to a water deficit in spring and then maintain that deficit all summer. This lowers the water content of fruit and increases sugars, ie brix. The hardest part is the spring transition. Irrigation begins when the shoot tips stop growing. Vegetative growth during summer is slow. The water deficit has been taken too far if the trees begin to drop leaves or the fruit shrivels. This watering regime is suitable for most fruits in the greenhouse because water demand is low but only for the very drought tolerant fruits outdoors in Alpine; mainly grapes, jujube, and figs.
>
> The floor of the greenhouse is covered with Extenday reflective fabric to increase light in the canopy, control weeds, and save water. This in part accounts for low greenhouse water needs. Light in the greenhouse is highly diffused by IRAC poly and ground fabric but is probably only 33-50% total PAR compared to outdoors.
>
> Little or no fertilizer is applied to greenhouse fruits. It's generally not needed since the fruit trees aren't competing with any ground cover vegetation.
>
> Average brix levels have been 18-25 for pluots and nectarines, 24-32 for sweet cherry, and 16-22 for apricots. Fruit size is generally good despite limiting water as much as possible. Flavor King pluot sometimes averages 200 grams and several nectarines 3-4 inches, ~300-450 grams. Fruit size is reduced by greater water deficits. For instance nectarines running ~28 brix at higher water deficits are 50-70% the size of 18-22 brix fruit.
>
> Key pest is spider mites which build up in late May. There are many new miticides available for control.
>
> The authors single most favorite fruit is Honey Royale nectarine for it's sweet and incredibly rich flavor. Other favorites are the other Honey and Arctic series nectarines, Orangered and Robada apricot, Flavor Supreme and Flavor King pluot, Strawberry Verte fig, Sweetcrisp blueberry, and Summer Royal grape. Summer Muscat is a great tasting grape but has small berries and cracks.
>
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GardenWeb Member: fruitnut - February 11, 2005