How to Plant a Miniature Garden in a Big Pot, Part 1
Planting a miniature garden in a big container creates room for more fun, more plants and more ideas. You can visually break up your design into a couple of smaller garden rooms within that one big pot, with paths leading to and fro. You can make a huge yard with several focal points happening around the container, or have enough room for a small house or building, a particular favorite of fairy gardeners. We talk about the different kinds of pots that can be used miniature gardening in our new book Gardening in Miniature: Create Your Own Tiny Living World, but here are a few more tips on how to save some time and money – and your back – when working with very large pots or containers.
What’s Deep? What’s the Minimum?
What do we consider a deep pot for miniature gardening? Any pot that is deeper than 14″, in my opinion. We recommend at least 8″ of soil so the miniature garden can stay together for a couple/few years before needing repotting. This allows the trees and plants to grow and weave together and you still get that aged-garden-look after a couple of years that is very enchanting.
How to Keep Your Big Pot and Plant It Too
Another popular question when planning a miniature garden in a huge pot is, “Should I put something in the bottom before I start planting?” Yes, and there are several reasons why you can go ahead fill that big container up with some sort of filler, leaving 8″ to 10″ from the top of the pot, before you add regular potting soil that will make you, and the plants, happier in the long run.
The miniature garden plants that we recommend to use are usually small to start with, so they don’t need a lot of soil to get growing. I find some types of plants tend to falter when planted in a huge container full of soil, as most plants prefer a smaller root environment when they are young. We call it “swimming in soil,” when the water wicks away from the plant’s roots to the bottom of the pot where gravity pulls it, and the moisture doesn’t stay around the roots where it is needed. Then the roots dry out, the plant starts to stress and falter. By using filler, it shortens the depth of the soil, prevents the water from wicking, the soil stays damp longer and the roots stay happy.
Fill ‘Er Up
Another reason to use filler on the bottom of the pot is huge pots can get really heavy. The spot you choose may be perfect for that garden this summer and into next summer but you may want to eventually move it. The two most popular ways to fill up your pots are:
Styrofoam peanuts or popcorn: Most packing peanuts are biodegradable now so put them in a plastic shopping bag, tie the bag shut and place the bag upside-down in the pot so water doesn’t get inside and stagnate. If you are using a really big pot, use several of bags-full and fill the pot up to about 10” to 12” from the top.
Upside-down black plastic nursery pots: Start with big 1 or 2 gallon pots in the center
of the bottom of the pot and work in the upside-down 4” pots, squishing them so they fill in as much space as possible. You can cut a couple of pieces of cardboard and layer it on top of the upside-down pots to create the “bottom” of the pot, or you can just start filling up the pot with soil.
We’ve heard of people using upside soda-cans and they would work only if they are rinsed out really, really well. Otherwise the sugar in the soda would draw unwanted pests to your container.
Note that this is for miniature gardening with small plants. Bigger plants mean more roots. If you are creating mixed containers of regular perennials and nursery plants (aka trees and shrubs) you may want to use potting soil all through your container to leave plenty or room for root growth.
SOIL CONCERNS: Use organic potting soil with no added fertilizers or water-retaining polymers. Your miniature garden plants don’t need it and the added fertilizer will burn the roots of the miniature and dwarf conifers.
POTTING SOIL VS. TOPSOIL: Potting soil has all the necessary nutrients and micro-organisms for a contained environment. If you look closely, you’ll see rich, dark organic matter, bits of sand and perlite or vermiculite mixed in to keep the potting soil from becoming a big lump of dirt over time.
Topsoil is plain soil, without the added ingredients for pots and containers. It is used to amend the soil in garden beds where any water drains naturally. The plant’s roots have all the room they want and can find nutrients on their own.