General Cultural Practices - Plant Spacing & Crop Layout

Plant spacing is determined by two main factors:
1) The availability of light to the canopy - Plants must be far enough apart so that a maximum amount of light reaches the leaves for optimum photosynthesis.
2) The availability of water and nutrients to the roots - Plants must be far enough apart so that all plants have an optimum supply of these items.
*Plant spacing in “vining” greenhouse crops, including tomatoes, is much closer than for field crops.
Example: Field (bush) tomatoes = 4000 – 5000 plants/acre.
Hydroponic greenhouse tomatoes = 10,000 – 11,000 plants/acre.
*Why? A vine has a much smaller diameter than a bush, so they can be closer together and the leaves will still obtain optimum light for photosynthesis. The roots of a plant growing in hydroponics receives all the water and nutrients it requires. They are “spoon-fed” and do not have to grow large systems. The roots of a field grown plant will be more spread out as they search for water and nutrients in the soil matrix. Therefore, field grown plants must be positioned far enough apart to avoid competition of neighboring plants for water or nutrients. NOTE: Drip irrigation allows for closer spacing.
*Typical hydroponic plant spacing:

• Tomatoes = 2.5 – 3 plants per square meter
• Peppers = 2.5 – 4 plants per square meter
• Cucumbers = 1.25 – 3 plants per square meter
• Melon = 2.5 - 3 plants per square meter
  

*The typical layout of the greenhouse for vining vegetable crops is in rows tending approximately north and south. This is important because during the day the sun moves from east to west and if the rows were also set up east to west the southern most rows (in the
northern hemisphere) would shade the rows behind them. Typically, tomatoes are also grown in “double rows”. These double rows are usually 5-6 feet apart. With 3 plants per Rockwool slab (1 meter long each) or perlite bag (about 36”), sets of 2 slabs/bags are placed side by side. With 6 plants per slab/bag a single row of slabs/bags is used. Overhead support wires are set at least 2 feet apart.