5 Tips for Successful Container Gardening

I almost bought a condo last year. The whys and wherefores aren’t really relevant here, but the experience did get me thinking about my gardens (naturally), and I spent much of the winter thinking about deck and patio gardening.

Even though I remained put after all, still surrounded by a yard and gardens, I decided to step up my container gardening efforts.

I’ve grown things in pots all of my adult life (including urban apartment balcony gardening, y’all), and there’s nothing I won’t try to grow in a pot. If your container is large enough with strong supports, you can grow it. Even corn. And pumpkins. Tomatoes. Blueberries. Ginger (yes!). Herbs, herbs, and more herbs.

Some plants, like peppers, loooove containers. I grow hot chili peppers in pots and by August, I’m picking dozens of chilis from these plants every single week. I chop them up and freeze them and [boom!] a year’s worth of diced chilis, all from an 8″ pot.

I also grow cooking staples in pots, like green onions, which I keep near the kitchen door for fast retrieval, rain or shine. Green onions do really well in containers, too, and they’re easy to reseed all summer long.

My container garden is off to a great start this spring, so I thought I’d share the tips and hands-on wisdom that I’ve gained over the years. Container gardening rocks!

1. Seasonality matters.

Temperature impacts plants in pots more acutely than plants in the ground, which get extra snuggly protection and temperature moderation from both heat and cold. Exposed pots, not so much.

When purchasing plants or sowing seeds, understand the vegetable’s temperature limits. Lettuce greens, for example, are an excellent early spring crop, as they need cool weather to thrive. Once June heat sets in, however, the plants switch to propagation mode and bolt (flower) to produce seed.

That’s not to say that you can’t extend the season: I drop shade cloth between my salad greens and the sun, which lets light through but keeps the direct heat punch of the sun from their leaves. Ambient temperatures will still send the greens toward bolting, but it slows the pace considerably. We’ve had numerous days over 80°F so far this spring, but my salad greens garden bench is still lush and crisp:

At the other end of the season, note which plants are frost sensitive. Perennials that are out of your growing zone often thrive happily indoors. Rosemary is one such plant. Although I plant it in a garden bed for the summer, I transplant it to a pot every October and bring it indoors.

The bay laurel shrub I purchased this year is another frost sensitive perennial. I’m growing it in a pot, and will bring it indoors when the weather turns cold (just in time for lots of soup with bay leaf flavoring!).

2. Choose the proper container, both size and type, to accommodate the plant and any necessary supports (stakes, trellises, etc.)

When selecting a pot for your vegetable, keep in mind the size of the plant as an adult, not just the cute little tike you currently hold in your hand. Peppers typically grow to 3 feet tall; tomatoes, 6 or more. Even seemingly small herbs will bush out and produce large root systems.

Although counterintuitive (especially if you’re a seasoned grower of indoor houseplants), I’ve found that a too-large pot is rarely a mistake. Vegetables are super-heavy feeders, and a growing plant squeeeezed into a small pot produces a tight nest of roots too tangled to adequately take in water and nutrients.

Pots can be plastic or clay, but make sure they have drainage holes. Avoid the “self-watering” pots that retain water in the bottom compartment, keeping the soil wet. Vegetables don’t like to have wet feet — they need good drainage. Yes, it means more watering, but the reward is a healthy root system.

Many gardeners prefer the breathability of clay pots, but, honestly, I’ve had great success with both clay and plastic. (Do note that plants in clay tend to need more frequent watering, especially in bright sun and hot temperatures.)

Also take into consideration any supports that the adult vegetable plant will need. A large pot or storage tub usually provides enough room and stability to include stakes and trellises.

(Side note: I just love watching vining cucumbers grow. They send out spirally tendrils that seek supports to grab on to. Crazy fascinating. It doesn’t matter where you place the support, the tendrils will find it and wrap themselves up tight around it. How do they do that without eyes?!)

3. Nutrition, nutrition, nutrition

Most potting soil mixes today are a disaster. Made mostly (if not completely) of peat moss, they have very few nutritive properties for vegetables, with the added characteristic of drying out drier than the desert.

I use a 50/50 mix of organic potting soil and clean, organic compost. I also mix in a healthy dose of perlite, which keeps the soil loose and airy, and Plant-tone granulated fertilizer (by Espoma).

Because of the good drainage you provided via smart pot selection in #2 above, a portion of soil nutrients will leach out along with excess water. No problem; just replace it. I prefer to fertilize frequently with a dilute fish and seaweed solution, rather than less frequently at full strength.

4. Mind the weather

Plants in pots are more vulnerable to strong winds and heavy rains. Even if your pot is huge and heavy — like the tomatoes above — and is not in threat of tipping over, the plants are still exposed to wind shear, hail, and blowing rains. When storms are predicted, be on the safe side and move pots to the ground or floor, preferably behind some protection, like a wall or covered grill or deck furniture. Nothing is more heartbreaking than to nurture a productive, fruiting plant all summer long, only to have it smashed in half in a dive from the deck rail.

D’oh!

BTW, the plant above survived the fall, although the pot is cracked neatly in half all the way around (the shards in the photo above are from the drainage saucer). This is my red mustard plant — the leaves were tasty all spring, and now it’s flowering and producing seed pods. I hope to collect the mustard seeds. 🙂

5. Know the plants’ needs.

In all the years I’ve grown basil, this is the first year I’ve grown it in a pot outdoors. I made a noteworthy mistake this spring: the pot sat on my exposed deck rail day and night. We had a lot of rain. Frequent rain. And basil’s soil was always very wet.

Just two weeks after potting, the plant started showing signs of distress — browning that looked like sunburn (but wasn’t) and curling. The basil plants in my garden beds were beautiful and flourishing under the same rain. But the difference was that the potted basil in its little pot remained drenched day after day, while the soil in the other basils’ garden beds wicked away excess water quite efficiently in between rains.

Once I moved the potted basil to a covered but sunny location and began reasonably scheduled watering, the plant recovered quickly and pushed out healthy new growth (see how pretty, above left?). Basil likes to dry out in between waterings (not desert-peat-moss dry, but mostly dry). I knew that, but didn’t take the voluminosity of spring rains into proper consideration. (Drainage wasn’t the issue — it was simply that the soil was constantly wet due to nearly continuous rain.)

Some vegetables, like celery, are warm-weather summer crops, but dislike high heat and super bright sun. I’ve had more success with celery in a pot than in the ground, because I can move the plant to a shady spot during extra hot, 100°+ spells, which we seem to have with more and more frequency here in the Ohio Valley.

Happy producers, like my hot chili peppers, benefit from regular harvests: picking the fruit allows the plant to divert energy from ripening that particular pepper to developing new fruit. The more you pick, the more you grow. How cool is that?

It’s not too late to start your own container garden. Selection at the nurseries and farmers’ markets might be dwindling, but you still have time to plant your favorite summer vegetables. Who wouldn’t like a gorgeous cherry tomato plant on the patio? (Add a sweet little pot of Genovese or sweet basil, and hello, Caprese salad!)

Happy gardening!

Karen xo