Best Aquarium Plants for 40-Gallon Tanks: Complete Stocking Guide

Setting up a 40-gallon planted tank is one of the most rewarding experiences in the aquarium hobby. With 36" × 18" × 16" of space to work with, you have plenty of room to create a stunning underwater landscape with live plants.

In this guide, we'll cover the best background, midground, and foreground plants for your 40-gallon aquarium — all available at Canton Aquatics with our live arrival guarantee.

Tank Specs at a Glance

• Dimensions: 36" × 18" × 16"
• Substrate needed: 25-30 lbs for 2-3" depth
• Recommended lighting: 30-40W full-spectrum LED
• Filtration: HOB or canister rated for 40-60 gallons

Background Plants

Vallisneria Spiralis

Italian Val grows 16-24" — ideal background for 40-gallon tanks. Low maintenance and beautiful flowing movement.

Amazon Sword

A classic centerpiece that grows large enough to anchor the background of a 40-gallon without overwhelming it.

Rotala Rotundifolia

Fast-growing stem plant with pink-red tips under good light. Creates stunning color contrast.

Midground Plants

Anubias Barteri

Larger anubias variety — broad leaves create visual anchoring points on driftwood and rocks.

Bucephalandra

Rare epiphyte with iridescent leaves. Slow-growing but stunning. Attach to hardscape.

Hygrophila Corymbosa

Temple plant — grows tall but can be trimmed to midground height. Easy and colorful.

Foreground Plants

Dwarf Hair Grass

Classic carpet plant. Benefits from CO2 but will slowly carpet without it in moderate light.

Staurogyne Repens

Compact, low-growing stem plant perfect for foreground and midground transition zones.

Pearl Weed

Versatile — grows as carpet in high light or bushy midground in lower light. Very easy.

Stocking Tips for a 40-Gallon Planted Tank

• Start with easy species — Java Fern, Anubias, and Vallisneria are nearly impossible to kill and establish quickly.
• Plant densely from day one — this helps prevent algae by out-competing it for nutrients from the start.
• Use root tabs for heavy root feeders like swords and crypts. Liquid fertilizer benefits column-feeding plants.
• Don't bury rhizomes — Anubias and Java Fern should be attached to hardscape, not planted in substrate.
• Be patient with crypts — they commonly "melt" after transplanting but grow back stronger.

Frequently Asked Questions

How many plants do I need for a 40-gallon tank?

For a well-planted look, aim for 15-25 individual plants across all zones. Start with fewer and let them fill in, or go heavy from day one to suppress algae.

Do I need CO2 for a 40-gallon planted tank?

Not necessarily. All the plants in this guide can grow without CO2 injection, though CO2 will accelerate growth and enable more demanding carpet plants. Start low-tech and upgrade later if desired.

What substrate is best for a 40-gallon planted tank?

Nutrient-rich substrates like aqua soil work best for root-feeding plants. Inert substrates (gravel, sand) work too — just add root tabs for nutrients. You'll need roughly 25-30 lbs for adequate depth.