square planter inserts for large pots Seeley Cube PlanterSeeley Cube Fiberglass Planter Steel Reinforced Large Block for Indoor Outdoor Plants and Trees. Entryway, Patio, Privacy, Balcony One Planter Unlimited Possibilities Material: Professional grade fiberglass for extreme durability and a refined aesthetic. Structural Integrity: Internal steel reinforcement on 20", 24", and 30" sizes to ensure perfectly straight walls. Application: Versatile design for privacy screening, spatial division, and entryway

Seeley Cube Fiberglass Planter - Steel-Reinforced Large Block for Indoor /Outdoor Plants and Trees. Entryway, Patio, Privacy, Balcony

One Planter - Unlimited Possibilities

• Material: Professional-grade fiberglass for extreme durability and a refined aesthetic.

• Structural Integrity: Internal steel-reinforcement on 20", 24", and 30" sizes to ensure perfectly straight walls.

• Application: Versatile design for privacy screening, spatial division, and entryway framing.

• Indoor / Outdoor: Beautifully finished, and optimized for high-traffic commercial interiors, rooftop decks, and expansive outdoor patios.

• Finish: All Weather UV-resistant architectural matte finish available in Classic White, Grey, and Black.

• Durability: Engineered to be shatterproof, frost-proof, and fade-resistant for year-round exposure.

• Weight: High strength-to-weight ratio allows for easy placement while maintaining stability.

• Drainage: Equipped with pre-drilled drainage holes and removable rubber plugs.

• Free Fast Shipping - All Orders. 30" Cube - 7/10 Pre-Order

Why Designers Choose the Seeley Cube

The Seeley Cube is the foundational choice for anyone who appreciates clean, minimalist geometry. If you have ever seen a standard plastic planter warp or fade after a single season, you will appreciate the industrial-grade difference here. It is designed to be a permanent, design-forward extension of your architecture.

In professional settings, these are most often used to create a "ceremony of arrival" at entryways or arranged in a rhythmic series to create a "living wall." Because the lines are so crisp and the matte finish so refined, the Seeley Cube defines space—like an open-plan office or a sprawling patio—without adding visual clutter. It anchors the environment, allowing your greenery to take center stage.

The Science: Why Steel-Reinforcement Matters for Large Planters

Most large planters suffer from "bellying"—a phenomenon where the sides bulge outward once filled with heavy, wet soil. This ruins the architectural silhouette. To prevent this, NMN Designs integrates internal steel reinforcement into our 20", 24", and 30" models.

This engineering ensures that even when housing a heavy, mature tree, the walls remain perfectly plumb and vertical. Combined with our commercial-grade fiberglass, you get a vessel that handles extreme thermal expansion (from scorching summers to sub-zero winters) without the cracking or brittleness found in standard resin or plastic pots.

Engineered for Performance: Indoor and Outdoor Versatility

The Seeley Cube transitions effortlessly between environments. For interior use in a foyer or gallery, keep the rubber plugs inserted for a watertight seal. For outdoor installations on a deck or patio, simply remove the plugs to ensure vital drainage and oxygen for the root zone.

Recommended Tree and Plant Pairings by Size:

• 14" Cube (Medium): Ideal for architectural foliage and "tree-like" indoor plants. Best for Snake Plant, ZZ Plants, or a Spider Plant. Perfect for office corners or flanking a residential console table. Outdoor - Ornametal Grasses, Small Plants.

• 20" / 24" Cube (Large and Extra Large): The perfect size for entryway ceremony and ornamental trees. Ideas include Evergreens and Boxwood Topiaries, Ornamental Grasses, Olive Trees, or Fiddle Leaf Figs. For a vertical architectural look, Sky Pencil Hollies are excellent.

• 30" Cube (XXL -Extra-Large): Designed for specimen trees and high-impact privacy. This volume is required for larger trees such as Japanese Maples, Dwarf Citrus (Lemon/Lime), or Serviceberry. To create a privacy screen, plant a series of Emerald Green Arborvitae or Tall Ornamental Grasses.

Pro-Tips for the Best Results

• High-Wind Stability: For exposed roof decks or coastal balconies, add 3 inches of heavy gravel at the base before adding soil. This lowers the center of gravity, ensuring your privacy screen stays upright during heavy gusts.

• Thermal Protection: While the fiberglass is frost-proof, using an insulated liner inside the planter in extreme northern climates can help protect the root balls of perennial trees, ensuring they return season after season.

The Seeley Cube Planter is made in India by NMN Designs®

Indoor Planter Box - Medium (14") to Extra Large (24")

Size Specifications

• Medium Planter - 14" L x 14" W x 14" Tall 
• Large Planter - 20” L x 20” W x 20” Tall
• Extra Large Planter - 24" L x 24" W x 24" Tall
• XXL Planter - 30" L X 30" W X 30" Tall  (Black Only)

Internal dimensions are 1/2" less for L x W x H

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