Understanding Potting Soil

A Practical Guide for New Brunswick Gardeners

March. 26th 2026

If you’ve spent any time in the garden this time of year in New Brunswick, you know how quickly things pick up once spring arrives. One minute, there’s still a chill in the air, and the next, everyone’s out planting up containers, refreshing window boxes, and getting a head start on the growing season.

 

One thing we see every year at Scott’s Nursery is how often potting soil gets overlooked—or treated like it’s all the same. In reality, the soil you choose can make a big difference in how your plants grow, especially with our mix of cool nights, damp conditions, and warm summer days here in the Maritimes.

 

Whether you’re planting up a few patio pots or going all-in on container gardening, understanding your potting soil is one of the easiest ways to set yourself up for success.

In this guide, we’ll walk through what potting soil really is, what’s in it, and how to choose the right mix for whatever you’re growing this season.

What Is Potting Soil (And What It Isn’t)

Despite the name, potting soil isn’t actually “soil” in the traditional sense.

Instead, it’s a carefully blended growing medium designed specifically for containers—things like pots, hanging baskets, window boxes, and planters. Unlike the soil in your garden, it’s made to be lightweight, well-draining, and consistent from bag to bag.

 

That consistency is key, especially here in New Brunswick, where natural soil can vary quite a bit from one yard to the next.

So what makes it different?

Potting soil is designed to:

  • Drain excess water easily (important during our wetter stretches)
  • Hold just enough moisture for plant roots
  • Allow air to move through the mix so roots don’t suffocate
  • Stay loose instead of compacting over time

What it’s not meant for:

  • Filling garden beds
  • Replacing topsoil
  • Using directly in the ground

A common mistake we see is using garden soil in containers. 

It might seem like a good idea, but it tends to:

  • Compact quickly
  • Hold too much water
  • Limit airflow to roots

In containers, that usually leads to struggling plants—or worse, root rot.

Why this matters locally

With our Maritime climate—cool springs, humid summers, and the occasional stretch of heavy rain—having a potting mix that balances drainage and moisture retention is especially important.

 

A good potting soil gives you control, no matter what the weather decides to do.

What’s in Potting Soil and Why It Matters

If you’ve ever opened a bag of potting soil and wondered what you’re actually looking at, you’re not alone. Most mixes look fairly similar at a glance—but what’s inside can vary quite a bit, and those differences matter.

 

At its core, a good potting mix is all about balance. You want something that can hold moisture, drain well, and still leave room for air around the roots.

 

Here’s a breakdown of the most common ingredients you’ll see in the mixes we carry at Scott’s Nursery, and what each one does.

Base Materials 

(The Foundation of the Mix)

These make up the bulk of your potting soil.

 

Peat Moss

  • One of the most common base ingredients in Canadian-made mixes (like ProMix, Lambert, and others)
  • Holds moisture well
  • Slightly acidic, which works for many plants

Coco Coir 

(less common, but growing in popularity)

  • Made from coconut husks
  • Holds water similarly to peat
  • Considered a more sustainable option

👉 Around here, peat-based mixes are still the most common—and they perform well in our climate, especially when blended properly.

Aeration Ingredients 

(For Drainage & Airflow)

These are what keep your soil from turning into a soggy, compacted mess.

 

Perlite

  • The small white particles you’ll see in the mix
  • Lightweight and excellent for drainage
  • Helps keep soil loose and airy

Vermiculite

  • Holds more moisture than perlite
  • Helps retain nutrients
  • Often used in seed-starting or moisture-loving mixes

👉 If you’re planting things that don’t like sitting in water (like many houseplants), mixes with more perlite are usually a good choice.

Organic Matter 

(For Nutrients & Structure)

Some mixes include added organic components like:

  • Compost
  • Aged forest products

These help:

  • Add nutrients
  • Improve soil structure
  • Support healthy root development

Fertilizers 

(Built-In Plant Food)

Many potting soils come with nutrients already added.

You might see:

  • Starter fertilizer (gives plants an initial boost)
  • Slow-release fertilizer (feeds plants over time)

These are especially helpful for:

  • Hanging baskets
  • Container gardening
  • New plantings in spring

Just keep in mind—they don’t last forever. Most will need additional feeding as the season goes on.

Why This All Matters

When you pick up a bag of potting soil, you’re really choosing how your plant will:

  • Access water
  • Get oxygen
  • Take in nutrients

A heavier mix might hold too much moisture during a rainy New Brunswick stretch, while a very light mix might dry out quickly during a warm, breezy week.

The goal is to match the mix to what you’re growing—and how you garden.

Choosing the Right Potting Soil 
for Your Plants

One of the most common questions we hear in-store is:
“Can I just use this one bag for everything?”

 

The short answer? You can—but you’ll get much better results if you match your soil to what you’re planting.

 

Different plants—and different setups—have different needs. And with New Brunswick’s mix of sun, wind, and moisture, those differences show up pretty quickly.

 

Let’s break it down.

Hanging Baskets & Window Boxes

These tend to dry out the fastest, especially once we get into warmer, breezier weather.

 

Look for a mix that:

  • Holds moisture well
  • Doesn’t dry out too quickly
  • May include moisture-retention features

Good options:

  • Peat-based mixes
  • Soils labelled for containers or baskets
  • Mixes with water-retaining additives

👉 Local tip: Even with a good mix, baskets in full sun around here can still need daily watering in July and August.

Indoor Plants

Indoor plants are a bit different,

they don’t like sitting in soggy soil.

 

Look for a mix that:

  • Drains well
  • Has good airflow
  • Contains more perlite

Good options:

  • Lighter blends (like ProMix HP-style mixes)
  • Specialty indoor or tropical plant mixes

👉 If you’ve ever had a houseplant decline “for no reason,” it’s often too much moisture around the roots.

Vegetables & Container Gardening

Whether you’re growing tomatoes on the deck or herbs by the kitchen door, these plants need a bit more from their soil.

 

Look for a mix that:

  • Holds nutrients
  • Retains moisture without getting heavy
  • Supports steady growth

Good options:

  • Potting mixes with compost or organic matter
  • Soil with added fertilizer (or plan to add your own)

👉 Local tip: With our shorter growing season, giving plants a strong start with good soil can make a noticeable difference in yield.

Seed Starting

Starting from seed? 

Regular potting soil can be a bit too coarse.

 

Look for a mix that:

  • Has a fine, even texture
  • Is low in nutrients initially
  • Drains well but stays lightly moist

Good options:

  • Seed-starting mixes

These help young roots develop without being overwhelmed.

Quick Match Guide

If you’re standing in the aisle and want a quick reference:

 

Hanging baskets / window boxes → Moisture-retaining mix

 

Indoor plants → Well-draining, perlite-rich mix

 

Vegetables / containers → Nutrient-rich potting mix

 

Seed starting → Fine, lightweight seed mix

 

If you’re ever unsure, that’s exactly what we’re here for, feel free to stop by and we can help you match the right soil to your project.

What Do Add-Ins and 
“Enhanced” Mixes Really Do?

When you’re looking at different potting soils, you’ll often see labels like:

  • “Moisture Control”
  • “Feeds for 3 Months”
  • “With Mycorrhizae”

It can start to feel a bit like marketing overload—but many of these add-ins do serve a real purpose. The key is understanding what they actually do, and whether they make sense for how you’re gardening.

Mycorrhizae 

(Beneficial Fungi)

This is one of the more natural—and useful—additions.

  • These are beneficial fungi that form a relationship with plant roots
  • They help plants:
    • Absorb water more efficiently
    • Take in nutrients more effectively

Best for:

  • Container gardening
  • Vegetables
  • New plantings

👉 Think of it as giving your plant a better root support system right from the start.

Moisture Control / 

Water-Retaining Crystals

These are designed to help regulate watering.

  • They absorb water when it’s available
  • Then slowly release it back into the soil

Best for:

  • Hanging baskets
  • Window boxes
  • Sunny or windy locations

👉 Local tip: These can be especially helpful during those hot, breezy stretches we tend to get mid-summer in New Brunswick.

Slow-Release Fertilizer

You’ll often see labels like “feeds up to 3 months.”

  • Nutrients are released gradually over time
  • Reduces the need for constant fertilizing early on

Best for:

  • Containers
  • Baskets
  • Busy gardeners who want a lower-maintenance setup

👉 Just remember: this isn’t a season-long solution. You’ll still likely need to fertilize later in the summer.

Wetting Agents

This is one people don’t always notice—but it’s important.

  • Helps dry soil absorb water again
  • Especially useful in peat-based mixes

Without it, very dry soil can actually repel water at first.

So—Are These Worth It?

In most cases, yes—but only if they match how you’re using the soil.

A few simple guidelines:

  • Low-maintenance containers? → Go for moisture control + slow-release fertilizer
  • Vegetable gardening? → Mycorrhizae + nutrient-rich mix
  • Indoor plants? → Focus more on drainage than extras

Keep It Simple

It’s easy to feel like you need the “perfect” mix with every feature, but in reality, a good base soil that matches your use will take you most of the way there.

Add-ins are just there to make things a bit easier.

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Related Products

Potting Soil vs Garden Soil vs Mulch vs Manure

At a glance, a lot of these products can look similar, especially when they’re all stacked beside each other in bags. 

But they each serve very different purposes, and using the wrong one in the wrong place can lead to disappointing results.

Here’s a simple breakdown to help make sense of it all.

Potting Soil (For Containers Only)

This is what we’ve been focusing on throughout this guide.

Best used for:

  • Pots
  • Hanging baskets
  • Window boxes
  • Indoor plants

Why it works:

  • Lightweight
  • Drains well
  • Designed for root health in confined spaces

👉 This is your go-to for anything above ground or in a container.

Garden Soil (For In-Ground Use)

Garden soil is meant to be used outdoors, directly in your garden beds.

Best used for:

  • In-ground planting
  • Raising or improving garden beds

Why it’s different:

  • Heavier than potting mix
  • Designed to blend with your existing soil

🚫 Not recommended for containers
In pots, it tends to:

  • Compact quickly
  • Hold too much water
  • Limit airflow to roots

Mulch (For the Surface Layer)

Mulch isn’t a growing medium—it’s more like a protective layer.

Best used for:

  • Covering garden beds
  • Around trees and shrubs

What it does:

  • Helps retain moisture
  • Reduces weeds
  • Regulates soil temperature

👉 Think of mulch as a blanket for your soil, not something you plant directly into.

Manure & Compost (Soil Boosters)

These are used to improve soil, not replace it.

Best used for:

  • Mixing into garden beds
  • Enriching existing soil
  • Boosting nutrients

What they add:

  • Organic matter
  • Nutrients
  • Better soil structure

⚠️ In containers, they should be used in moderation and mixed with potting soil—not on their own.

A Common Mistake to Avoid

Simple Rule of Thumb

One of the most common issues we see is using garden soil in pots.

It seems like a simple swap—but in our climate, especially with periods of steady rain, it often leads to:

  • Waterlogged containers
  • Poor root growth
  • Plants that just don’t thrive
  • In a pot? → Use potting soil
  • In the ground? → Use garden soil + compost
  • On top? → Use mulch
  • Improving soil? → Add compost or manure

If you’re ever unsure which direction to go, feel free to stop in—we’re always happy to walk you through it based on what you’re planting.

Common Questions About Potting Soil

What If There’s Fungal Growth 

on My Potting Soil?

If you’ve ever noticed a white, fuzzy layer forming on top of your soil, don’t panic. It’s actually quite common.

In most cases, these are harmless saprophytic fungi, which simply means they’re feeding on organic material in the soil.

 

Why it happens:

  • Moist conditions
  • Limited airflow
  • Organic matter breaking down (very normal in quality mixes)

What you can do:

  • Let the top layer dry out a bit between waterings
  • Improve airflow around the plant
  • Gently stir the surface of the soil

👉 Local note: With our humidity in New Brunswick, this tends to show up more often—especially indoors or in shaded areas.

When to be concerned:

  • If the plant itself is declining
  • If the soil stays constantly wet

Can You Reuse Potting Soil Every Year?

Yes—you can, and many gardeners around here do. 

But it does need a bit of refreshing.

 

To reuse potting soil:

  • Remove old roots and debris
  • Loosen the mix

Add:

  • Fresh potting soil
  • Compost or organic matter
  • A fertilizer source

This helps bring structure and nutrients back into the mix.

When not to reuse:

  • If the plant had a disease
  • If there were pest issues
  • If the soil is compacted or has a bad smell

👉 A good rule: if it looks and smells healthy, it’s usually safe to reuse with a bit of care.

Should You Mix Potting Soil 

with Other Materials?

Absolutely—this is where you can really tailor things to your plants.

Common additions:

  • Perlite → improves drainage
  • Compost → adds nutrients
  • Aged manure → boosts organic matter

Why mix your own:

  • Adjust for specific plant needs
  • Improve performance of basic mixes
  • Experiment and learn what works best in your space

👉 Local tip: If you’re dealing with a particularly rainy stretch, adding a bit of extra perlite can help prevent containers from staying too wet.

A Quick Takeaway

You don’t have to get everything perfect right away.

A lot of gardening—especially here in the Maritimes—is about:

  • Adjusting as you go
  • Learning from the season
  • Trying something a little different each year

And your potting soil is one of the easiest places to experiment.

What Makes a Really Good Potting Soil?

By now, you’ve probably noticed there’s no single “perfect” potting soil for everything—and that’s the point.

A really good potting mix is one that matches what you’re growing and performs well in our local conditions here in New Brunswick.

That said, there are a few things you should always look for when choosing a quality mix.

1. Good Drainage 

(Without Drying Out Too Fast)

You want a mix that:

  • Lets excess water escape easily
  • Still holds enough moisture for plant roots

In our climate, this balance is key. Too much moisture—especially during rainy stretches—can lead to root issues pretty quickly.

2. Light, Fluffy Texture

A quality potting soil should feel:

  • Loose
  • Airy
  • Easy to work with

If it feels heavy or clumpy right out of the bag, it’s probably not ideal for containers.

3. Consistent Mix (No Large Chunks)

Good mixes are uniform, meaning:

  • Even distribution of ingredients
  • No large sticks or debris

This helps roots grow evenly and access water and nutrients more effectively.

4. The Right Ingredients for the Job

Depending on what you’re planting, look for:

  • More perlite → better drainage
  • More organic matter → more nutrients
  • Added fertilizer → easier maintenance early on

5. Matches Your Gardening Style

Be honest about how you garden:

  • Water often? → You may want better drainage
  • Forget to water sometimes? → Look for moisture retention
  • Growing lots of containers? → Consider mixes with added nutrients

There’s no wrong answer—just what works best for you.

A Note on Brands

We carry a range of trusted options here at Scott’s Nursery, including:

  • Lambert
  • SoilMate
  • ASB Greenworld
  • ProMix (BX & HP)
  • Fafard
  • Sungro Horticulture

All of these offer solid products—the key is choosing the right type of mix within those brands for what you’re planting.

If you’re not sure, we’re always happy to help you compare and decide.

Start Simple, Then Experiment

If there’s one thing to take away from all of this, it’s that potting soil doesn’t have to be complicated.

Start with a good-quality mix that fits your project, and don’t be afraid to adjust as you go.

Try a different blend in one container. Add a bit of compost to another. 

See what works best in your space, with your watering habits, and through a New Brunswick growing season.

That’s how you really learn—and it’s part of what makes gardening so enjoyable.