This is a fantastic question that gets to the heart of successful urban gardening! A common medium-sized planter box from our collection, measuring approximately 24 inches long, 12 inches wide, and 12 inches deep, offers a versatile space for your plants. The realistic number isn't a single figure but depends entirely on the mature size of the plants you choose.
For a lush and healthy display, the key is to avoid overcrowding. Here’s a practical guide based on plant type:
For Herbs (like Basil, Cilantro, Thyme):
You can comfortably fit 3 to 5 herb plants. They can be placed relatively close together, especially if you harvest frequently. For example, one basil plant, one cilantro, and two to three smaller plants like thyme or oregano would thrive.
For Leafy Greens (like Lettuce, Spinach, Kale):
You can grow about 2 to 4 plants. Loose-leaf lettuce can be spaced about 6-8 inches apart, allowing for three plants. A larger kale plant might need the entire planter to itself or be paired with one smaller companion.
For Compact Vegetables (like Dwarf Tomatoes, Peppers, Bush Beans):
Realistically, plan for 1 to 2 plants. A single dwarf tomato or pepper plant will happily occupy most of the planter box due to its root system and top growth. You could underplant with a shallow-rooted herb like oregano.
For Flowers (like Petunias, Marigolds, Pansies):
For a full, blooming effect, you can fit 4 to 6 plants. These annuals are often grown for a dense visual impact and can be placed closer together than edible plants.
The Golden Rule: Always Check the Plant Tag.
The most accurate answer will always be on the plant's nursery tag, which specifies the correct "spread" or spacing. This ensures each plant has enough room for roots, nutrients, and air circulation, preventing disease and promoting a bountiful harvest or beautiful bloom. Happy gardening