Build an n8n AI Agent That Plans Your Content Calendar

Planning a campaign usually means a blank spreadsheet and an afternoon of "what do we send on Thursday?" In this free n8n tutorial you build an AI agent that takes one campaign theme and plans two weeks of emails and social posts, then saves every item to a Google Sheet your team can review.

What you will build

You will build a Campaign Calendar agent in n8n for Harbor & Pine Coffee Roasters, a small online coffee brand used as the example. n8n is a workflow tool that connects apps together. An AI agent in n8n is a model that can reason about your request and then use tools, and the tool here is Google Sheets.

In the test at the end you tell the agent: "Plan a two-week email and social calendar for our Holiday Ember Blend launch, starting Monday Nov 2. Our offer is free shipping over $35." It comes back with six items across two weeks: three emails and three Instagram or Facebook posts, each with a date, a channel, a topic and a line of draft copy. Then you say "save the calendar to the sheet" and the agent writes six rows into a spreadsheet called Campaign Calendar, each one marked Draft.

Who this is for

This is for marketers at small businesses who plan campaigns by hand: a store owner launching a seasonal product, a marketing coordinator who owns both the newsletter and the social accounts, or a small agency team building calendars for clients. If your calendar lives in a spreadsheet already, this puts a planning assistant in front of it.

It is also a good first n8n project. You meet every core piece of an agent (trigger, system prompt, model, memory and a tool) on a real marketing job.

Step by step: what you do

• Get n8n: go to n8n.io and sign up for an account.
• API key: add a small amount of OpenAI credit, then create a secret key, name it and copy it.
• New workflow and chat trigger: start a workflow and add a trigger that fires on a chat message, so you can talk to the agent.
• AI Agent and system prompt: add the AI Agent node, open its options, add a system message and paste the prompt. It describes Harbor & Pine, its audience and tone, caps email at two a week, bans invented discounts and health claims, and lists the five fields to return.
• Chat model: pick OpenAI, create a credential with your key, and choose gpt-5-mini.
• Memory: add Simple Memory so the agent remembers the calendar when you ask it to save.
• Sheets tool and spreadsheet: add the Google Sheets tool, create a sheet named Campaign Calendar, and type five headers: Date, Channel, Topic, Draft Copy and Status.
• Configure Sheets: sign in with Google, pick Append Row, choose the Campaign Calendar sheet and Sheet1, then click the button next to each column so the model fills it in.
• Test the agent: open the chat, give it the campaign theme, read the plan, then ask it to save the calendar to the sheet.

Why it works

The system prompt does the planning thinking you would otherwise do in your head. It tells the agent who the brand is, who it is talking to, how often it can email, and that every item needs its own angle, like the launch, how the coffee is made, how to brew it, gifting and a customer question. That is why the plan does not repeat the same "buy now" message six times.

The five columns in the sheet match the five fields in the prompt exactly, so the agent always knows where each piece goes. Memory lets you review the plan first and save second. And every row is saved as Draft, so nothing goes out until a person reads it.

How to use this in your business

Rewrite the system prompt for your brand: what you sell, who buys it, how often you email, which channels you actually post on, and which offers are real. Keep the five columns, or rename them to match the calendar your team already uses.

Then run it at the start of every campaign. Give it the theme, the dates and the offer, and you have a first draft calendar in a minute. Your team edits the draft copy in the sheet, changes Status to Approved or Scheduled, and you move on to writing the full emails and posts.

What you need

• For the practice copy here: nothing. No accounts are touched.
• For the real build: an n8n account, an OpenAI account with a little credit, and a Google account for Sheets.

Frequently asked questions

Is this course really free?

Yes. Stepthrough is completely free, and the practice copy needs no accounts. To build it for real you need your own n8n, OpenAI and Google accounts, and some of those cost money once you use them for real work.

Can n8n create a content calendar in Google Sheets automatically?

Yes. In this lesson an AI Agent node with the Google Sheets tool appends one row per calendar item: date, channel, topic, draft copy and status. You ask for the plan in chat, then ask it to save.

How much does the OpenAI part cost?

You pay OpenAI per request, not per month. The lesson adds $10 of credit, and planning a calendar with gpt-5-mini costs a small fraction of that. Check OpenAI's current pricing for exact rates.

Will the agent publish posts or send emails on its own?

No. This agent only plans and saves drafts to a spreadsheet, each marked Draft. Sending and posting stay with you or your usual tools.

Do I need to know how to code?

No. Everything is done by clicking nodes and pasting a prompt. You watch each step first, then do it yourself in the practice copy, and "Do it for me" is there if you get stuck.

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