April 24, 2024

When I was in college, I had three pots with tiny plants growing on my windowsill. They were my connection with horticulture. Those long nights trying to figure out why a horticulture major was taking calculus I’d look at those plants and they’d encourage me to keep pushing on. Somehow, we made it through.

Container gardens give us all hope. Whether we live on a spacious estate or on the third floor of an apartment, there’s always room for a few pots and the plants to grow in them. Look at any garden center — you can tell by their inventory and displays. Container gardening has never been more popular. Let’s break it down to the basics.

It starts with the pots

The container is to its plants like a frame is to its artwork. You don’t want it to overwhelm. You never have to apologize for choosing something simple. Here are some random considerations that need to be put into the final choice.

Right up front, it must have a drain hole. Without one, minerals (salts) will accumulate to toxic levels. (Think of the Great Salt Lake.) You must have a way of flushing them out the drain hole with a very heavy watering periodically.

The pot needs enough weight to offer ballast. Your plants will grow tall during the summer. They can become top-heavy and topple during windstorms. Terra cotta and ceramic containers stand up better, for example. Plastic pots, not so much (using this measure).

The container should be appropriately sized and shaped for the type of plant(s) that you’ll be growing in it. In case you come across them, old type clay pots were designated as “standards” (same height as diameter), “azaleas” (three-fourths as tall as wide), and “tubs” (half as tall as wide). The term “rose” pots has been used for clay pots that are taller than wide. “Pans” is a term used for very shallow, wide pots.

You want to repot your plants when they become rootbound. My rule of green thumb here is that when a plant becomes three or four times as tall or wide as the pot in which it’s growing, it’s time to examine the roots. If they’re encircling the inside of the container, it’s time to water it, let it drain for a couple of hours, then carefully tap it out and replant it into the next larger size pot. If the roots are tightly packed, I’ll use a sharp knife to cut through the outer layer in a couple of places.

It’s best not to “over-pot” a plant, that is, to plant it into a pot that is far too large for its needs. The soil won’t dry out uniformly. Parts will remain soggy too long and roots won’t grow evenly throughout.

Choosing or mixing your potting soil

When I pick up a shovelful or bag of potting soil I want to exclaim, “Wow! I thought that would be heavier.” If I’m mixing my own potting soil I’ll use 45% sphagnum peat moss, 20% finely ground pine bark mulch, 25% horticultural perlite, and 10% expanded shale. The shale serves essentially the same purposes as the perlite, but it’s heavy, so it gives my mix that ballast I mentioned earlier.

You’ll notice that I’ve included no native soil in my mix. It’s too unpredictable, and in many cases it’s too hard to get it to combine well with the amendments. And, I may fine-tune the mix just a bit. If I’ll be growing ferns, African violets, or other plants that require highly organic soil, I’ll decrease the perlite/shale portion and step up the amount of sphagnum peat. By contrast, if I’m growing succulents, I’ll increase the expanded shale percentage.

I’m often asked about re-using potting soil out of my containers. Since these are the most prime of my gardening spaces, I always feel like they deserve the best attention I can give them. For that reason, I always start with freshly mixed soil each season. I re-use the old soil in my in-ground beds. It’s certainly fine when used in tandem with compost and other amendments.

Potting the plants

I buy the plants for my container gardens at one time so I can do all my potting simultaneously. I use primarily large pots (14-inch and larger) around our landscape, so I’m looking at planting several plants in each of the pots.

“Thriller” plants go in first. They’re the center plants that are the focal points of the planting — the upright spikes that stand above all the others.

“Filler” plants may be foliage or flowers, and they make up the bulk of the plantings that surround the tall plants. They’re generally rounded, and they often are of a contrasting texture and color. It’s quite possible that you’d have a couple of types of filler plants for interest.

“Spiller” plants tumble across the edges of the pots and down their sides. They’re usually trailing growers, hopefully somewhat compact. Probably they should be fairly soft textured with small leaves and flowers so they don’t take away from the most visible “super stars” up above.

Grouping your pots

Position your containers so they’ll look like a family. They should be compatible in container and flower colors and textures. It’s good if one of the plants is used as a common thread through each of the pots, either as a filler or spiller, just to tie things together. Odd numbers of pots always look visually restful.

I use concrete rounds as bases for my large containers. That keeps the pots from making direct contact with the soil so that roots don’t grow out the drain holes and into the soil. In the winter, those concrete stones sit idly by in the groundcover beds waiting for their next time of use. To my eye, they look better than an abandoned spot of mud.

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source: star-telegram

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