In the Greenhouse

Current Crop Greenhouse Tomatoes: Oct. 2010

Greenhouse Tomatoes What's happening in the fall greenhouse?

In spite of the normal problems, the fall greenhouse tomatoes are coming along well.  We expect harvest to begin around November 1st. 

So what normal problems are we dealing with?

1- Whiteflies:  After spotting these tiny white insects on the plants I contacted my supplier and ordered Encarsia Formosa, a parasitic wasp that parasitizes the white fly pupae.  Two releases are necessary for good control with a two week interval between releases.

2- Excessive Heat:  Temperatures in the 90's are not favorable to tomato pollination.  As everyone in central NC knows we have endured many days in August and September above 90 degrees F.  As a result fruit-set was slow initially. 

3- Humidity and Disease:   Any experienced NC greenhouse grower knows our late summer hot, humid days create plenty of night-time moisture in the greenhouse.  Our most troublesome tomato disease, powdery mildew, thrives in these moist conditions.  Even though we have been unable to conquer the powdery mildew we have always been able to produce a good crop in spite of it.

4- Cloudy Days:  The arrival of much needed rain brought with it several cloudy days.  In addition to aiding disease growth, cloud cover is also not favorable to tomato pollination.  Again fruit-set has been temporarily hindered.

5- Cool Nights:  Tomatoes need night-time temperatures above 55 degrees F for proper pollination.  With night temperatures expected  to dip into the 40's in a few days it is time to fire up the wood heater.  Exercise, and plenty of it, will be a side benefit of hauling wood and maintaining a fire that will keep our tomatoes cozy.



Planting schedule - July & August

Savoy Cabbage    Broccoli    Chinese CabbageCrisp Savoy Cabbage, delicious Broccoli, Chinese cabbage and Collards - It's time to start the fall garden!  


      The first or second week of July I plant broccoli, cabbage, and collard seed in plug trays to grow plants for the home garden.  Also tomato seeds are planted in July to grow plants for the fall crop in the greenhouse.

      My seeds germinate under florescent  lights and once they reach appropriate size I put them in 3 inch pots and take them to the greenhouse.

      Carrot seeds can be planted directly in the garden this month for carrots that will overwinter in the garden.  Garden soil can be amended with peat moss and compost to make a loose bed for carrots to grow in.  I add one pint of lime for each 5 gallons of peat moss to balance the acidity.  Also potatoes can be planted in the garden for fall harvested potatoes.  They may not grow as well as spring planted potatoes but are still good.  I mulch them heavily to keep the soil as cool as possible.


Broccoli  Cabbage, collards and broccoli  Greenhouse tomatoes                            

Remember we are in USDA Planting Zone 7
Fall is a great time to plant those green vegetables.  In our home garden we plant broccoli, collards, savoy cabbage and Chinese cabbage plants in August. Lettuce plants can be planted as well.  It is also a good time to sow seed for mixed greens such as kale, mustard and turnip.  We should be able to harvest these vegetables through mid-winter.

This is also the time we plant tomato plants in the greenhouse for fall tomatoes.  These tomatoes should begin ripening in October and continue through December.  Vine ripened tomatoes for Christmas, what a treat.

Growing Tomatoes: Greenhouse

Sawing wood to heat the greenhouse      Preparing tomato beds      Planting tomato plants  

Heating the greenhouse can be one of the greatest expenses.  Fortunately we have been able to cut the cost by heating the greenhouse with scrap wood collected from local businesses.  Keeping in mind that healthy soil promotes healthy plants we periodically add leaves and compost to our tomato beds to increase soil fertility and soil life.  This year our tomato plants were planted the last week of March and the first week of April with harvest expected to begin in May.

Fertilizing tomato plants    Pollinating tomatoes   Insects trapped on yellow sticky card

I use a simple hose end sprayer to fertilize our tomato plants.  Our organic fertilizers do not go through the drip irrigation system as easily as non-organic liquid fertilizers.

Organic Fertilizer Mix    Pour into a 1 quart container:  1/8 cup liquid fish fertilizer (nitrogen), 1/8 cup Biolink 0-5-5 (phosphorous and potassium), 1/8 cup Epsom Salts (magnesium; if you applied dolomitic lime to the planting bed you do not need the epsom salts as dolomitic lime contains magnesium), 1 teaspoon Borax (boron).  Finish filling the jug with water.  This is a concentrate and should be enough for 40 - 50 plants. I place this in a hose end sprayer, attach to the end of my garden hose and water the plants.  The number of times that I fertilize is dependent on existing soil fertility and the availability of soil nutrients.

Some hand pollination is beneficial as the greenhouse environment does not get the benefit of wind and insect pollination that occur outside. 

Potato aphids on tomato plant After planting, yellow sticky cards were placed in the greenhouse to trap pest insects.  Once potato aphids were discovered on the plants I removed the yellow sticky cards and released a parasitic wasp, called Aphidius, to parasitize the aphids.  The yellow cards had to be removed because Aphidius are also drawn to them.  Aphidius Ervi effectively control potato aphids while Aphidius Colemani control Green Peach Aphids.  You can also purchase a mix of Aphidius to control a number of different aphids.  We have used these parasitic wasps to control aphids in the greenhouse for many years.  Lady Bugs may also be purchased for an effective control of aphids in the greenhouse.