Cold-hardy strawberry plants may seem unlikely candidates for greenhouse growing until you consider the experience of Mark Cox, a farmer whose transplant greenhouses stood empty for nine months of the year. He decided to plant greenhouse strawberries that ripened a month after the last garden-grown strawberries were history, and found a cash-rich crop. Whether you wish to get strawberries earlier or later than the typical season, a greenhouse is your best bet. Indoor growing is particularly useful for organic berries since the ceiling and walls keep out insect and wildlife pests.
Fill 12-inch-deep containers halfway to the top with organic compost. Select containers that are 6 inches in diameter and have multiple drain holes.
Set one young strawberry transplant into each pot. Choose transplants that are healthy and grown organically. Tuck the compost in around the edges of the root ball, maintaining the same level of soil as in the original container. Put the pots into the greenhouse in February. Place them at least 2 inches apart in an area that gets between six and eight hours a day of sunlight. Keep the temperature in the greenhouse at 60 degrees Fahrenheit or less until the plants have flowered.
Irrigate the strawberries from the bottom, if possible, to prevent crown rot. Give strawberries frequent water during establishment and when the weather is dry. Feed the plants with a balanced organic liquid fertilizer such as 12-12-12 every two weeks from planting until the moment the flowers open.
Remove the blossoms the first year if you choose June-bearing strawberries, the kind that offer one abundant crop late in June every year. For all other types of berries, pollinate the plants by passing a small paint brush over the center of the plant's blossoms. Once flowering is completed, use a water-soluble organic fertilizer that is high in potash to encourage fruiting.
Tuck straw between berries and soil if the fruit of your berry cultivar droops to the ground. Alternatively, use pieces of fiber mats. Both straw and mats prevent berry rot and also help keep down weeds.
Harvest your berries when ripe. Remove mulch when the last berries have been picked. Reduce the temperature in your greenhouse after harvest and leave it cool through the winter. Strawberry plants require a chill period to initiate flowering.
Things You Will Need
- Planting containers 6 inches in diameter
- Organic compost
- Strawberry transplants
- Organic liquid fertilizer
- Organic high-potash fertilizer
- Straw or fiber mats
- If you must water your berries from above, do so in the morning to reduce the amount of time they remain wet.
- Greenhouse berries are largely protected from attacks by slugs, snails, rodents and insects, but they still can catch diseases. Select disease-resistant cultivars and find organic treatments for diseases that occur. For treatment of fungal diseases, make an organic spray by adding 2 drops of organic olive oil, 2 drops of liquid soap, and 3 tbsp. of baking soda to a gallon of water.
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