Here are the things you need to know – container gardening basics – to succeed in your own garden.
One of the delights of our summer garden is our container gardens. We use them in a variety of ways and whether you have acres of gardens or a postage stamp patio, you might consider the use of containers to extend and improve the range of plants you grow.
What Plants Can I Grow In Containers?
To begin with, any plant you can name can be grown in a container.
I know that some garden books will say give just the contrary advice but if I can grow plants -from bananas to cosmos and roses to zinnias in a container, I don’t see why you can’t. I grow my lavender collection in containers beside our front door and they lend a certain “style” and fragrance to our entrance way.
Here are a few good gardening techniques for making those containers a hit in your garden this summer.
What Soil To Use
Good container soil is the key to success. Use a good quality soilless mix in the container. Don’t use a cheap brand or regular garden soil because they will compact and turn to concrete over the course of the summer. A good soilless mix is composed mostly of peat moss and perlite (perhaps with a very small amount of compost) and that’s about all.
A good soil like Pro-mix or Fafard will more than pay for themselves in superior plant performance this summer. And, they are light enough that you can still move most containers even when fully filled.
How To Feed
I also use a fish emulsion fertilizer on a weekly basis for my container plants. This stuff is the best container food in the world, producing huge, fragrant rose blossoms and jungle-like growth on our window boxes. There’s nothing else like it because it has all the major and minor nutrients a container plant needs.
Most other liquid fertilizers lack the minor and trace elements a plant requires for superior growth. Remember that soilless mixes, unlike natural mineral soils in your garden, do not have these trace elements as part of their natural composition so you have to provide them if you want your plants to grow properly.
The Essential Watering Rule
There’s a very simple rule of thumb for growing vegetables in a container or anything else for that matter:
Water until water pours out the bottom.
In this way, you know all the soil, from top to bottom is thoroughly wet.
Air Temperatures To Understand
Somewhere around 83F (a bit higher for some and lower for others) plant leaves stop respiration and shut down to conserve water. They essentially stop growing. Because a plant actually gets taller, grows leaves etc at night after the day’s energy has been stored, this high day temperature will reduce the ability of the plant to grow.
In extremely high heat periods, it’s a good idea to give container plants a part shade condition – even those that grow in the sun. Simply pick up and move your containers during the heat of the day or tuck them into a part sun spot until the heat wave is over.
Not much you can do about this but you can control the next variable.
Soil Temperatures in Containers
Soil temperatures will also stop growth through reduced nutrient uptake – the higher the soil temperature, the less food the plant absorbs.
Soil gets hotter in smaller containers – it easily approaches air temperature in small containers. Dark colored containers – such as black plastic – absorb more heat and get hotter.
Adding water to “cool down” the plant will only swamp the plant and kill it.
The solution is to use light, reflective colored containers and to give plants some shade during the heat of the day.
Where Can I Grow Containers
The bonus of container growing plants is that you can place the container where you need it. For example, if you have a paved patio but want to grow plants up a trellis, then simply put a large container beside the trellis and plant morning glory seeds in the container. Those seeds will germinate quickly and if you train them towards the trellis (gently lay them down in the direction of the trellis when they threaten to go the other way) they’ll quickly find it and start climbing.
You could use the back of a round container for morning glory seeds and fill the front with impatiens and trailing lobelia so your container not only grows upwards but also gives you a flower show.
Multi-layer Your Planting
That’s another key to remember. Don’t just think of your containers as having just one use. We used to grow pansies under our containerized roses. The pansies would give us a great show in the early spring before the rose had leaved out and then would climb upwards into the rose when the rose shaded it. The pansy would act like a short vine and would poke its flowers out in unexpected spots. As I recall, we used a mid-blue pansy with a peach coloured rose to give a super colour combination.
You can also tuck herbs like basil into flower pots so you can harvest a few leaves whenever the need for a toasted tomato sandwich strikes (you *have* to use basil on those sandwiches if you want to really experience the joy of a tomato sandwich) I note that if a container is large enough for 8 full, large shovels full of soil, it is large enough (with daily watering) to grow a tomato plant.
Water Plants – Why Not?
Why not plug up the hole of a container and grow small water lilies in one. I did this last year and the lily was a great hit in the garden. I even managed to keep a few small rosy barb fish alive all summer in one clay-coloured container that was semi-shaded.
I did however discover the hard way that the high water temperatures generated in small black plastic above-ground water containers was not good for fish even if it was great for the dwarf lilies.
Perennials and Winter Survival
One of the newest gardening trends is to grow perennials in garden containers and I confess I’ve done this for many years now. The only problem with this is with winter survival. In the case of our lavenders, they spend the winter on our porch. The porch is protected from the wind and moderated by house temperatures and the lavenders survive nicely.
An attached garage would be equally appropriate. A garage or shed that is not protected by house heat would be too cold for good winter survival. (We don’t want perennial roots to get to 5F.)
An alternative suggested by some writers is to dig the perennials out of the pot and plant them in the garden for the winter. You can then dig them up for the container in the spring or simply leave them in the garden to grow. There is no perennial that will not survive in a large container so you are only limited by your imagination.
And that’s the essence of good container gardening. Get a big enough container (I use 16 inch clay pots) and a big enough imagination and you can extend your gardening and growing to anywhere you happen to spend some time.