What Are the Best Ways to Fill a Raised Garden Bed?

What Are the Best Ways to Fill a Raised Garden Bed?

When you’re new to gardening, even the best ways to fill a raised garden bed can feel confusing. Should you use dirt, bagged soil, compost, or something else entirely?

The good news is that it doesn’t have to be complicated. By following a simple, step-by-step method that builds healthy soil from the bottom up, you can create a thriving raised bed without the guesswork. Let’s break it down so you can start growing with confidence.

Best Ways to Fill a Raised Garden Bed

It seems simple. The bed is empty, and you need to fill it up. 

Use dirt right? Bagged soil? compost?

It seems that it just got complicated. I promise, new gardener, it’s not difficult at all. The best ways to fills a raised garden bed follow a simple five step process that will have you on your way to gardening in no time.

1. Prepare the bed
2. Layer in Organic Material
3. Compost on top
4. Pack and Level
5. Protect with mulch

1. Preparing the Bed Site

Preparing the area to place your raised garden beds may be the most important part of establishing your new gardens. Location and materials are the key ingredients to your raised bed success.

Growing Spaces

When deciding where to place your raised beds, consider the amount of of sunlight your plants will be able to receive during your growing season. Most vegetable plants need six to eight hours of sunlight in order to produce fruit. Don’t forget those things that need partial shade too though, such as lettuces, spinaches, and some herbs.

Underneath Protection

Keeping animals out of the bottom of your bed may be an issue one day. In our area, we have pocket gophers that tunnel through and destroy large swaths of growing spaces overnight. They can come in, eat the roots of our plants, and destroy the soil with their tunnels and mounds. I wish that I’d used hardware cloth on the bottom of my beds to prevent this.

If you have a known problem with voles, moles, or gophers in your area, you may want to add metal mesh under your beds. Protect your plant roots with a mesh that has quarter inch or smaller holes to keep destructive varmints out.

Preventing Weeds

You can easily snuff out grass and weeds where you want to establish your new raised bed by using cardboard or weed cloth on the bottom of your bed. No sprays are needed. 

Just gather some used cardboard, and lay is out slightly outside of your bed dimensions. I like to use two layers. Make sure that no native soil or plant growth peeks between your pieces of cardboard to be sure your suffocate those, and they won’t bother you later.

If you choose landscape fabric or weed cloth, make sure that you go with something biodegradable to be sure you aren’t adding microplastics to your vegetable garden. This contractor type paper works well. Save the heavy duty plastic cloth for your walkways between your beds.

Skip the Rocks or Gravel

Some people like to add rocks to the bottom of their raised beds for drainage. This is generally unnecessary if you choose quality materials to fill your bed with. Promoting good drainage through good soil is a better route.

Furthermore, adding rocks can actually hinder good drainage by holding water in. Too much water in your beds will drown your plants.

2. Layers of Organic Material

Alright, let’s get into the best ways to fill a raised garden bed now. Plants will need quality garden soil to grow well and produce, and you can build up your soil by layering in organic materials now. You can play around with how much of each layer you want, depending on the size of your beds.

Keep wood chunkier materials, like wood chips, limbs, and leaves at the top and bottom of your raised beds. You don’t want to mix up too much carbon-heavy items into the space where your plant roots will be. Instead, let them rot at the bottom of the bed, or hold moisture at the top of the bed.

The middle space is where you want a finer, nutrient rich growing medium.  You need 6 to 8 inches of soil to grow in. This is also where you want to make sure that your raised be drains well. You can mix added perlite or sand to help balance your soil for good drainage.

Deep Raised Beds

If you have deep beds to fill, you can save money by filling the bottom with whatever organic materials that you have on hand. Dead limbs and logs in the bottom take up a lot of space, just make sure that you leave the top 8 inches for quality soil.

I recommend this hugelkultur method if your beds are 18″ or deeper. The layers will look something like this:

• large rotting logs and sticks
• fill the gaps with dead leaves
• spent hay or animal bedding
• old compost or native soil
• 6-8″ purchased soil (buy it by the cubic yard from landscape supply companies for affordability)
• compost
• dead leaves
• mulch

Shallow Raised Beds

If you have shallow raised beds, 12″ or less, then you’ll want fewer layers overall so that there’s plenty of space left to grow plants on top. You can go with the same layering configuration as deep beds, but skip the logs. Each layer would be considerably smaller than those of deeper beds.

Or, a better option, and how I’ve filled my shallow raised beds, looks like this:

• Spent animal bedding, small sticks, and dead leaves
• native top soil 
• 6-8″ of purchased soil
• compost
• mulch

I don’t recommend planting in beds smaller than 12 inches deep, unless the bottoms are open to the ground. This is especially important for root vegetables like carrots, or fruiting crops with deep root systems, such as tomatoes.

3. Compost at the Top of the Bed

Note that no matter what size bed you’re filling, the next step is to use compost over the bulk of our soil. Remember, compost adds microbial life to your soil, which unlocks nutrients for your plants.

As the compost breaks down, the microscopic critters make available nitrogen, phosphorus, potassium, and more for your plants to feed on. These nutrients are also washed down throughout the soil as the bed receives water. 

High quality compost helps your beds retain moisture so that your soil doesn’t dry out. This not only helps your soil life thrive, but your plants too. 

The kind of compost that you choose to feed your garden is really personal preference. Mushroom compost, animal manure compost, or homemade compost from kitchen scraps are all acceptable.

4. Level the Soil

Minimize any initial sinking by packing and watering each layer as you fill your beds. Get into your bed, and pack down those dead leaves by stomping them down, and then water them well. This removes large air pockets, giving the bed more room to fill with soil.

Sinking will still happen overtime, especially as those larger, woody pieces break down. You can replenish the soil by continuing to add to it each growing season before you plant.

Be careful not to pack your soil too tightly. You obviously want some water retention, but you have to balance that with good drainage. A great way to achieve the right consistency is to soak each layer as your put them in, which also helps level the soil as you go.

5. Don’t Forget the Mulch

Last, make sure that you mulch the top of your soil beds. I like to start with dead leaves, chopped finely to create leaf mold, or grass clippings. Water them well, and then cover them over with wood chips.

Yes, you can buy cheap, bagged mulch to top your raised bed, but skip the dyed versions. You can use fresh wood chips as well. We always say to use what you have access to.

For me, I highly recommend pine shavings, particularly those used as animal bedding. I’ve been helping a farm friend clean her goat stalls so that I can take the soiled bedding for my garden.

Goats have a cold manure, meaning it won’t burn plants and can be used right away without composting. This has been a game changer in the soil health of my garden.

What Not to Put in Your Raised Garden Bed

There are some things to be wary of adding to your garden beds.

1. Don’t use tarps or plastic sheeting on the bottom of the bed. This will cause water to pool in the bottom, and you’ll drown your plants.

2. Uncomposted hot manures will burn your plants as well. Fresh cow, horse, chicken, or pig manures should be composted before using them in your food gardens. Cold manures from rabbits, goats, sheep, and alpacas are excellent alternatives to use right away. 

Some new gardeners are a little worried about using manure on their edible plants. I count these organic additions as good stuff, but I wouldn’t use them on anything that I’m going to pick to consume soon. For example, fast growing lettuces or root crops probably shouldn’t receive manure as a top dressing.

3. Spent hay should be avoided if you don’t know of its original source. Hay farmers often spray their crops with long term persistent herbicides that will contaminate your soil, killing your plants. This can take years to cure. Additionally, hay is typically filled with seeds that will sprout in your garden beds causing a weedy mess.

4. Organic materials that were diseased or sprayed should not be used in your raised bed garden. This can be a problem if you received wood chips from a tree company that helped remove sick or sprayed trees from another property. Introducing disease or toxins to your garden is the last thing that you want. 

5. Too many soil amendments without a soil test. Be careful using too many additives, especially if you choose to use a quality bagged soil. 

Can I Mix My Own Soil for Filling Raised Beds?

You sure can. A good combination is one part compost to one part peat moss, and then add in some blood meal and perlite. This might look like:

• 5 gallons peat moss
• 5 gallons compost
• 1/2 gallon perlite
• 1 cup blood meal or worm castings

Maintaining the Soil in a Raised Bed

Remember, your beds will continue to sink over time, needing replenishment of bulk material and nutrients. I like to add a 2-3 inch layer of compost to the top of my beds each growing season before planting.

Additionally, I use a high quality bagged soil every time I plant in my beds. If I’m transplanting starts, then I’ll pull back the top layers of mulch and compost, and then drop in my transplant, surrounding the root system with new soil. This helps to keep fertility and diversity up in my growing spaces.

Last, once every year or two, I’ll purchase quality soil in bulk to replenish my raised beds. For best results, pull back the mulch before adding anything new, then cover the soil surface again with that same mulch.

Concluding the Best Ways to Fill a Raised Garden Bed

Setting up a raised garden bed is one of the most rewarding steps you can take on your homesteading journey. When you build your beds with intentional layers, protect them from pests, encourage rich soil life, and top everything with the right mulch, you’re creating more than just a place to grow vegetables. 

You’re crafting a long-term ecosystem that will only improve each season. Remember that soil is a living resource; it shifts, settles, and evolves over time. By topping off with compost regularly, adding fresh soil as needed, and continuing to use what you have on hand, you’ll keep your beds productive and fertile for years to come. 

With these simple steps, you’re well on your way to growing abundance right outside your door. 

Happy planting!

Donna and her family have been homesteading for most of their 20+  years together in some shape or fashion. She currently lives on their 20 acre farm where they grow as much food as possible. What started as a just a few laying hens, has grown into large gardens, pastured poultry, pork, and lamb. They are continuously evolving their small farm to not suit their family’s needs, but also providing to their local community. Donna’s favorite part of the family farm is her self-built micro-dairy, where she gets to love on dairy cows while serving her local community. Milking, cheesemaking, and processing dairy have become the soul of their homestead and the center of their farm.