How to Pollinate Hydroponic Tomatoes

Tomatoes in an outdoor garden are pollinated by the wind or by insects, and they require a specific frequency of vibration to release their pollen. This frequency poses a challenge for those growing tomatoes hydroponically indoors. In a greenhouse, fans can induce a small amount of pollination, but yields will be low. In a very large greenhouse, growers often pollinate hydroponic tomatoes by keeping a colony of bumblebees indoors. Small-scale and at-home growers will have to manually vibrate each tomato plant to release the pollen.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• Bumblebees
• Greenhouse
• Sugar water
• Bee feeder
• Electric toothbrush or vibrator

Pollinating with Vibrators

1. Purchase an electric toothbrush or pollination vibrator. Garden supply stores that specialize in hydroponics will sell electric vibrators that run at the right frequency for tomato pollination. An electric toothbrush also works.

2. Turn the electric toothbrush or vibrator on and touch it to every flower cluster on every plant. This should be done every day or every other day between 10 a.m. and 2 p.m.--the period when pollen levels are the highest.

3. Maintain an ideal environment for hydroponic tomatoes. Mechanical pollination attempts are most effective when humidity levels are around 70 percent and temperatures are below 85 F during the day and above 65 F at night.

Pollinating with Bees

4. Purchase a hive of bumblebees. Compared to honey bees or other insects, bumblebees are more efficient pollinators for hydroponic tomatoes and also are more suited to life in a greenhouse. Bumblebees are available by mail from specialty garden supply stores. Bees are sold by quantity, and the quantity you need depends on the size of the greenhouse. The store selling the bees can help you determine how many bees you need.

5. Install your bees in the greenhouse following any instructions supplied via the retailer. Place the cardboard shipping box in a location you can keep it in and leave it sit undisturbed for an hour. This allows the bees to settle down after the trip. Close any ventilation windows on the greenhouse before freeing the bees. After you open the box, it can serve as their home.

6. Maintain a bee-friendly habitat. Bumblebees are happiest and most productive when kept at temperatures between 59 and 77 F. Never use pesticides or other chemicals when pollinating with bees.

7. Feed bees a sugar water solution (3 parts sugar to 2 parts water) in a specially designed bee feeder that is available from beekeeping supply stores. Even in a greenhouse filled with diverse crops, a hive of bumblebees will need more nectar than is available naturally. Your bees should come with instructions for how much sugar water to offer and how often.

8. Replace the bees as needed. Depending on the size of the hive and greenhouse, a colony of bumblebees kept indoors will have a lifespan of 4 to 12 weeks.

Tips & Warnings

• Bees are more effective pollinators than electric vibrators or toothbrushes, and also greatly reduce labor time. However, they are more expensive and are not practical for small-scale growers or people who do not have a dedicated greenhouse.

References

• Hydroponic Tomato Pollination
• Greenhouse Tomato Culture
• Natural Pollination with Bumblebees