Thriving Greens: How to Fill Large Planters Properly

Have you ever looked at a large planter, full of lush, healthy plants and wondered just how it’s done? Just like an artist with their palette, the gardener must also masterfully mix colors, textures… and something far less glamorous – dirt.

But what lies beneath that surface layer is more than meets the eye.

A well-filled large pot can be your own little slice of Eden in any space – a testament to life’s vibrancy. But getting there isn’t always as simple as tossing in some soil and planting away. Oh no! The secret to creating this vibrant canvas goes beyond choosing the right plants.


Let’s start by figuring out why good drainage is key for plant health. Even bacteria have a role to play here! Then, we’ll dive into the secrets of choosing top-notch potting mixes that fuel growth from the inside.

Table Of Contents:

Understanding the Importance of Proper Drainage in Large Planters

Proper drainage is essential for the well-being of your plants; it isn’t merely a good suggestion.

Think about root rot – that nasty little problem caused by excess water around plant roots.

It can make your indoor planters look more like horror movie props than decorative features.

Root rot breeds harmful bacteria growth and turns vibrant green leaves into wilted messes. So, what’s our knight in shining armor here? Adequate drainage.

This useful guide will tell you exactly what to put at the bottom of your planter for optimum moisture drainage.

The Role of Drainage Holes in Preventing Root Rot

Adequate drainage works wonders against root rot and its sidekick, bacteria growth. When there are no puddles pooling at the base of your potted plant, it has room to breathe.

If we consider each hole as a tiny escape route for excess water – voila. You’ve got yourself quality potting soil that isn’t drowning under H2O pressure but flourishing instead.

Choosing the Right Potting Mix for Large Planters

The secret to a lush, healthy plant lies in its roots. And what surrounds those roots? You guessed it, potting soil.

Selecting High-Quality Potting Soil

A high-quality potting mix can make your green thumb shine brighter than a garden gnome’s hat. It’s like choosing between fast food and grandma’s home-cooked meal for your plants.

Use quality potting soil tailored specifically to your plant’s needs. Not all soils are equivalent, so don’t assume that just because you’ve got dirt on your hands any old ground will do the trick.

Two of my favorite companies for potting soil are Fox Farm and Espoma. You can often find them in your local garden store or online.

Garden soil is too heavy and may lead to drainage issues – think of it as trying to drain water through chocolate cake (and not the moist kind.).

On the other hand, high-quality potting mixes ensure good moisture retention while providing essential nutrients for optimal growth – like an all-inclusive resort vacation package but for plants.

Natural and Environmentally Friendly Pot Fillers for Large Planters

if you are using your plants for medicinal purposes, look into natural potting fillers first. As long as they haven’t been treated with any pesticides or chemicals, there typically won’t be any leaching from these materials which may cause health problems.

You will want to replace these with new materials at the end of the year as they might break down.

Here are a few organic materials to consider:

  • Sticks: Take some sticks you’ve found fallen on the ground, break them up, and put them in the bottom of your planter as a lightweight filler.
  • Pine cones: They’re not just festive decorations! Just imagine those tiny crevices guiding excess water away from your plants’ roots like an efficient highway system.
  • Coconut fiber: This is a lightweight option that is also eco-friendly.
  • Wood chips: But why stop there? Ever thought of wood chips? These guys can provide the same benefits too. They may be fairly dense though so watch to make sure your plants are draining well.
  • Wood logs: This is a heavier option, so be sure you are able to move the planter if necessary.

Let us know if you have any creative ideas on how to give old items new life in your garden adventure.

Lightweight Pot Fillers for Large Planters

Filling a large planter can feel like wrestling with an elephant. You’re sweating, and straining, and that potting soil bag doesn’t seem to get any lighter. But guess what?

You can cut back on the amount of potting soil you use and replace it with lightweight pot fillers. These are also great options if you have an already heavy planter.

Many of the suggestions here are man-made and have the potential to leach chemicals, so these are wonderful options for decorative pieces and not medicinal.

  • Plastic pots
  • Old soda
  • Plastic Milk Jugs
  • Plastic Water Bottles
  • Packing Peanuts (non-degradable)
  • Foam Pool Noodles (cut up)
  • Styrofoam

Save yourself from unnecessary chiropractor bills and money on costly soil bags with some of these options. Many of you were probably planning to recycle them anyway!

Heavy Pot Fillers for Large Planters

If you move some of your houseplants outside for the summer you may need to be mindful of the wind and weigh it down. Or consider these if it is a top-heavy plant.

Take a look at some of your options below.

  • Broken ceramic
  • Large rocks
  • Wood Logs
  • Broken pieces of cinderblock

These fillers not only help prevent your potted plant from toppling over but also promote better water flow through improved drainage.

Using Recycled Materials as Pot Fillers for Large Planters

Filling up large planters with potting soil can get pricey. So, why not lighten your wallet’s load and go green at the same time?

You’ve got a goldmine of potential pot fillers right in your recycling bin. We mentioned many of these options earlier in the article.

The trick is simple: you can cut or crush these items into smaller pieces and voila. They become perfect lightweight filler materials that won’t compromise on drainage. 

Plus, you’ll be making an environmentally friendly choice by reusing what would otherwise end up in a landfill.

And again, if using plastic, be mindful of chemical leaving if using these options for medicinal purposes.

  • Milk jugs
  • Corks from wine bottles
  • Packing Peanuts
  • Broken Plastic Pots
  • Water bottles you forgot about in the car – they’re all game.

We toss out plenty of recyclable plastics daily. Why not give them another life while helping our plants thrive?

**Note: Clean the containers out before utilizing them to prevent unwanted bacteria growth.

Steps to Fill a Large Planter for Proper Drainage

Knowing how to properly fill and drain these sizable containers is crucial. So let’s get our hands dirty!

Step 1: Pick Your Planter

First things first – selecting your planter. Look for one with drainage holes at the bottom.

This helps excess water escape instead of drowning your plants’ roots (which they hate by the way). If it doesn’t have any, don’t fret! You can drill some yourself.

Cleanliness is next to godliness, right? Be sure to clean your planter if it was used previously. Rinse it out and make sure any old soil or roots are gone.

show room of empty clay pots

Step 2: Add the Base Layer (Pot Filler)

Start off by adding a layer of pot filler at the base of your planter.

Typically plants come with a general recommendation for what size pot (aka space) is needed for optimal growth. Put enough of your filler in so that the amount of room left above is enough for the needed amount of soil.

For example, if you have a basil plant that needs about a foot of depth, add filler to about 13-14 inches from the top of the pot.

Extra Notes:

  • If you have any whole bottles, consider capping them so water doesn’t collect at the bottom.
  • If you have a very tall planter and are using lightweight materials, it may be a good idea to place a brick at the bottom. It can help with stability so large plants don’t topple over.
  • Some people suggest putting landscape fabric on top of the filler to keep the soil in place. I will leave it to you to decide. I haven’t found it necessary, but others prefer it.

You can get landscape fabric at your local garden store or online. Here is a bio-degradable option if you’re interested.

Adding rocks to the bottom of planter

Step 3: Add The Potting Soil

Grab some high-quality potting soil recommended for your plant type and pour it on top of your pot filler until you place your plant in the pot and it is about 1-2 inches from the top.

Adding Soil to Planter

Step 4: In Goes Your Plant!

Now gently place your chosen plant into its new spacious abode and fill around it with more soil until only an inch or two below the rim remains empty – leaving room for watering without overflow.

Placing plant into green pot

Step 5: Firm It Up And Water Away

Gently press down on the surrounding soil. Now, water your plant until you see some drainage out the bottom of the planter.

And voila! You’ve successfully filled a large planter for optimal drainage and happy plants. Remember to always check on your green friends regularly – they’ll thank you with lush growth and cleaner air in return!

Filling the pot with soil around plant

Tips for Ensuring Healthy Plant Growth in Large Planters

Tip 1: Proper watering techniques are crucial to make sure your plants don’t feel like they’re on a water slide or stuck in a desert.

Plants can be picky about their drink just like us with our morning coffee.

Some prefer sipping slowly throughout the day while others love a good soak now and then. Get to know your plant’s thirst level – it’ll help prevent root rot and promote growth.

Tip 2: Fertilizing is another biggie. Think of it as adding some spice to your plant’s life – nutrients boost their mood (aka health) substantially. Only add what your plant needs though or it could hurt your plant.

FAQs in Relation to How to Fill Large Planters

Should you put rocks in the bottom of a planter?

Rocks can help with drainage, but they’re not always necessary. If your potting mix drains well and your planter has good drainage holes, you might not need them.

Is it OK to put Styrofoam in the bottom of a planter?

You can use Styrofoam as a lightweight filler for large planters. It improves drainage while reducing weight. Use styrofoam in plants used for design and not medicinal purposes in the event of chemical leaching.

What do you put in a large square planter?

Apart from plants, add quality potting soil mixed with compost or slow-release fertilizer. Consider adding fillers like pine cones or broken ceramics at the base for better drainage and to reduce the amount of soil you need to purchase

How high should you fill a planter?

The depth depends on what’s being planted. Generally, leave about an inch between the soil surface and rim for watering space.


Mastering how to fill large planters is no small feat. You’ve journeyed through the crucial importance of proper drainage and seen how it safeguards against root rot.

We learned about lightweight and heavy pot fillers, each with their unique roles in improving drainage while maintaining balance. Remember those natural materials? They’re not just environmentally friendly; they’re also your allies in creating thriving container gardens.

And let’s not forget our recycled warriors like milk jugs that save money while promoting recycling. Every step counts when preparing your planter, from cleaning to layering soil & plants correctly – these are all keys to unlocking flourishing growth.

Now you’re equipped with tools and techniques necessary for ensuring healthy plant life in your large pots! So get out there – let’s make this world greener one planter at a time!

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