August 14, 2026·7 min read

How to Write Landscape Architecture Specifications

A practical guide to writing landscape architecture specifications that hold up in the field, protect your firm, and reduce RFIs during construction.

Specifications are where projects get built correctly or where they fall apart. If your specs are vague, contractors fill in the gaps with the cheapest option available — and then you're writing RFI responses instead of designing.

Understand What Specs Actually Do

A specification is a legal document. It defines the quality, performance, and installation standards for every material and system on your project. It works in tandem with your drawings, and when there's a conflict between the two, most contract language gives the spec precedence. That makes errors in your spec more consequential than errors on your plans.

Specs also allocate risk. A well-written spec tells the contractor exactly what's required, which means deviations become their liability. A poorly written spec creates ambiguity, and ambiguity in construction almost always costs the owner money — and costs you credibility.

The other thing specs do: they force you to make decisions. You can't write a soil specification without knowing your compaction requirements. You can't write an irrigation spec without knowing your water source, pressure, and flow rate. The discipline of writing specs catches design gaps before the bid set goes out.

Choose the Right Specification Format

Most landscape architecture firms use one of two formats: MasterFormat or a proprietary office standard. For public projects and anything with a general contractor, MasterFormat is expected. The Construction Specifications Institute (CSI) MasterFormat divides work into divisions — Division 31 for earthwork, Division 32 for exterior improvements, Division 33 for utilities.

Within landscape architecture, you'll spend most of your time in:

Section 32 90 00 — Planting
Section 32 84 00 — Planting Irrigation
Section 32 80 00 — Irrigation (broader)
Section 31 22 00 — Grading
Section 32 14 00 — Unit Paving

For smaller private projects, a simplified proprietary format can work — but if the project ever goes to litigation, MasterFormat-organized specs read as more professionally credible. The trade-off is time: MasterFormat requires more upfront organization.

Structure Each Section Correctly

Every spec section follows a three-part format: Part 1 General, Part 2 Products, Part 3 Execution. Don't skip any of them, even when they feel redundant.

Part 1: General

This covers scope, related sections, references, submittals, quality assurance, and project conditions. Write the scope statement narrowly — it should describe exactly what this section covers, not everything on the project. Reference the standards you're requiring: ASTM, ANSI, AWWA, or ASLA guidelines as appropriate. For planting, reference ANSI Z60.1 (American Standard for Nursery Stock) explicitly. It defines container sizes, caliper measurements, and height tolerances so you don't have to.

Part 2: Products

Be specific here. "Approved equal" language is unavoidable, but define what equal means. For irrigation, specify the manufacturer and model number you designed around, then list the performance criteria a substitution must meet: precipitation rate, distribution uniformity, operating pressure range. For planting soil, specify the USDA textural class, organic matter percentage, and pH range — not just "good topsoil."

Part 3: Execution

This is where most specs get lazy. Execution requirements tell the contractor how to install, not just what to install. For tree planting, specify the excavation diameter (minimum 2x the rootball width), backfill compaction limits (no more than 85% Proctor density in the planting zone), staking duration (12 months maximum), and mulch depth (3 inches, kept 3 inches clear of the trunk). Every one of those numbers came from a failure I've seen in the field.

Write Planting Specifications That Hold

Planting specs are the most commonly underwritten section in landscape architecture. The drawings show what goes where; the spec defines what "correct" looks like.

Start with material quality. Reference ANSI Z60.1 and then go beyond it. Specify that trees must be free of co-dominant stems, that container stock must show no evidence of circling roots at the container edge, and that balled-and-burlapped material must have a solid rootball with no cracks. These aren't bureaucratic details — they're the difference between a tree that establishes and one that fails in year three.

Specify a plant establishment period with teeth. A one-year warranty is standard, but write in the conditions: the contractor is responsible for irrigation during establishment, replacement of any plant showing greater than 25% dieback, and a final inspection 11 months after substantial completion. Without that inspection trigger, warranties expire before anyone checks the plants.

For large projects, include a plant material approval process. Require the contractor to submit tagged samples or photos of proposed plant material before delivery. On a $2M planting contract, you do not want to see the trees for the first time when the crane is already on site.

Write Irrigation Specifications That Match Your Design

Irrigation specs need to reflect how you actually designed the system. If you designed to 0.5 inches per week application rate for turf zones, say so in the spec and require the contractor to demonstrate that rate during system startup. If you specified Hunter MP Rotators for a low-precipitation-rate zone, define the substitution criteria: matched precipitation rate within 5%, same arc adjustability range, same operating pressure window.

Specify controller type and smart controller requirements explicitly. If the project requires a WELO-compliant or MWELO-compliant controller with weather-based ET adjustment, name that requirement in the spec and reference the applicable regulation. Don't assume the contractor knows what's required.

Include a pressure testing requirement. Before backfilling, require a static pressure test at 150% of operating pressure for a minimum of 30 minutes with zero pressure loss. This one line prevents the most common irrigation defect: leaks at fittings that get buried before anyone checks them.

Common Mistakes Firms Make

1. Using another project's spec without updating it. The fastest way to get a specification wrong is to copy last year's spec and change the project name. Material standards change, local requirements change, and the design itself is different. At minimum, do a full pass through every Part 2 and Part 3 before issuing.

2. Specifying products you haven't coordinated with the drawings. If your spec calls for 4-inch caliper trees and your planting plan shows them in 5-foot-wide planting strips between sidewalk and curb, you have a conflict. The drawings and spec need to be designed together, not written separately.

3. Leaving "approved equal" undefined. Contractors will read "approved equal" as permission to substitute whatever is cheapest. Define the performance criteria a substitution must meet, and require submittals before substitution is accepted — not after installation.

4. Writing execution requirements that can't be inspected. "Install per manufacturer's recommendations" is not an enforceable execution requirement. Write requirements that a field inspector can actually verify: depth, spacing, compaction values, test pressures, mulch depths.

5. Skipping the submittals requirement. If you don't require submittals — shop drawings, product data, samples — you have no formal review point before materials arrive on site. For planting and irrigation especially, submittals are your last chance to catch substitutions before they're in the ground.

6. Treating the warranty section as boilerplate. One year is standard, but many jurisdictions and project types warrant longer — two years for trees on public projects is increasingly common. Specify what triggers the warranty clock (substantial completion, not final completion), what constitutes failure, and what the remedy is.

How Phasewise Handles This

Specifications sit inside a larger document production workflow, and the most common breakdown isn't the writing — it's tracking which sections are complete, who reviewed them, and whether the current version matches the issued drawings. Phasewise's project phase tracking lets you attach spec sections as deliverables to specific phase milestones, so nothing ships without a completion check. The submittal log feature carries directly into construction administration, giving you a single place to track spec-required submittals from the moment you write them into the spec through contractor submission and your review.