Phil McCann’s 10 step guide to your best containers ever!
Posted: February 16, 2015
Categories: Garden Survival Guides
About Phil McCann
Phil McCann has worked on BBC Gardener's World and is an experienced horticultrual consultant, previously working for the RHS, Unwins Seeds and Hillier Nurseries.
Phil has kindly used his experience to provide us with a great 10-step guide to perfect container gardening, leaving few excuses not to get started straight away.
Choosing the correct container
Containers come in all shapes and sizes and ultimately you should only choose one's you are happy with. After all, you are the one having to look at it every day for years and years. Funky plastic containers fit modern, cutting edge gardens whereas stately terracotta, getting cheaper every year, fit most gardens. But you don't even need to buy in containers. Baked bean and soup cans when emptied and cleaned make lovely little homes for single pelargoniums or a bunch of living basil.
It's also worth chatting to local restaurant owners who throw away larger metal cooking oil (or olive) containers. They are superb for growing bush tomatoes. Just ensure that before any planting your containers have plenty of drainage holes drilled in the base. Water has to be able to get out of the root zone for healthy plants to grow.
A common question is whether or not you can use garden soil in a container, or do you have to buy specially formulated compost. Sorry, the cheaper soil option isn't right. If you did use soil the chances are it will compact over time depriving roots of the essential oxygen they need to survive. Compost has a more open structure allowing roots to thrive over many years.
However, composts do run out of nutrients (whereas soil is a more living and vibrant environment) and these need to be replenished. Most composts will sustain good growth for around two months, then balanced fertilisers need to be added. It adds to the cost but it is the best way to help plants flourish.
Where your container ends up is entirely down to what you grow in it. Gardening isn't rocket science (unless you are growing rocket!) If your plants need a sunny spot – then bung the container in the sun! You get the picture. Containers placed against a wall will get a little more protection against the cold. The bricks give off the heat soaked up during the day. These same containers could well become drier than their counterparts out in the open. It depends on the direction of the rain.
That’s why hanging baskets, surely the most popular container around, need so much watering (and the fact there are twenty healthy, robust plants competing for water in a small area) It's also worth bearing in mind that if your container is to sit pretty over winter, water needs to run out of the bottom to prevent water logging. Site your pots just above ground or path or stone or concrete slab or decking or wherever – pot feet are available but bricks placed underneath the pot will do fine.
Planting trees and shrubs
I reckon you can grow anything in a container (yep, even trees) but only if you stick to some basic rules. Firstly, grow trees and shrubs in appropriately sized containers, and as they grow do pot it up into bigger pots. Otherwise we are entering the magical world of bonsai, and that's a completely different set of guidelines. Secondly, read the labels on any tree and shrubs you buy to find out how big they grow, how quickly and what kind of conditions they need.
Then thirdly, match it up with a container of choice, get those drainage holes sorted and place the container on pot feet or bricks and plant it up. Once planted up, most containers are heavy. Some plants need special conditions to thrive e.g. azaleas, rhododendrons and blueberries need ericaceous / acidic compost. It's worth doing the homework because such plants will begin to yellow and look extremely sad if plonked into the wrong kind of compost.
Nothing beats the thrill of seeing the first shoots appear through the compost surface from bulbs you planted months before. The idea is that daffodils, tulips and crocus bulbs are planted in autumn to flower the following spring whereas gladioli, agapanthus and lilies are planted in spring for flowering the same year.
They are also so versatile – plant up the bulbs ( or corms, or tubers – 'bulb' is a generic term for all this type of gardening) in containers using multi-purpose compost and leave them in a quiet part of the garden. Once the shoots appear bring them into the display area, let them develop, flower, thrill and delight and then, put them back to the quiet part for the leaves to feed the bulbs for next years display. In their place you can bring in more containers stuffed with interest.
Containers and vegetables
You don't need a garden the size of a small county to grow your own veg. You don't even need an allotment. You don't even need a garden. If you have a front door then you have space either side for containers of tomatoes. Substitute one for an aubergine, or a cucumber, maybe squeeze in a low trough of finger carrots, pack a hanging basket with cherry toms and throw in some small pots of herbs. Can't grow your own? Yes you can, in a can.
Most vegetables are now available to buy as young seedlings or you can raise your own from seeds. A windowsill, some pots, compost and seeds are all you need. Some crops ( toms and cues and peppers) can all stay indoors if you have the space, or simply choose outdoor varieties and grow them instead . And potatoes – they are, in my opinion, best when grown in containers.
Step 1: Find yourself some thick polythene sacks, or old compost sacks (turned inside out so they aren't too garish ) and fill with a 10 cm of compost
Step 2: Nuzzle a seed potato on the surface and cover with compost
Step 3: As the shoots appear cover with compost
Step 4: Repeat step 3 until near the top of the sack
Step 5: When near the top of the sack let the shoots develop
Step 6: Harvest your lovely spuds a week or so after the flowers die off
Watering and feeding
Just bear in mind that as the plants thrive in your containers they will need some care and attention.
Never ignore watering. In soil, in the garden, water moves freely and the more it rains, the more water the roots get. In a container, especially where plants produce a dense canopy that prevents water from even reaching the compost, you need to keep a close watch on anything becoming dry. You need to be handy with a watering can of water. It isn’t a chore through – it's called gardening!
After a few weeks the nutrients do run out of most composts. You can add nutrients through pelleted fertilisers (some release their nutrients slowly over a season saving you the bother of doing it every week) or a weekly feed will suffice – it depends on what is growing. A balanced or all round feed is best and I think seaweed extract is fantastic at producing the best crops, shrubs, trees or whatever you grow in containers.
Long term container care
In time, and this probably means two years for trees and shrubs in containers, you will need to carefully scrape off the top 4cm or so of compost and add new. Vegetables only hang around for a year, as do bedding plants so little attention is required (other than watering) Terracotta pots may degrade with time and become flaky – this is due to the water in the clay expanding and contracting as it freezes and thaws.
Eventually parts will break off, but so long as the pot is stable it only adds pure character. Algae will grow on most pots, especially on the shady side, but this is easily blasted off with a pressure washer or cleaned off with warm, soapy water.
Design with containers
A solo container adds drama to a garden, providing a focal point for the eye to rest and take in the beauty. A group of pots add height, texture and interest to a bare wall, and regimented lines of pots are perfect for a modern look. And remember, anything can be grown in a pot so a group of them can transform a bleak, concrete back yard into a green oasis providing blooms, food, perfume, texture and sound.
What can go wrong?
Any plant in any container is more reliant on you, its curator, than plants growing in the garden. Nothing needs to go wrong if you water and feed when required. It's actually easier to spot bugs and beasties getting a hold as you are in daily contact with your containers. Nip the nasties in the bud and all will be well.
OK, a tall pot may blow over in a gale (not if planted with substantial compost and crammed with plants though) and if you don't raise them ever so slightly off the ground the compost may, in a wet winter, get waterlogged, but pot feet are on your shopping list aren’t they? No, I'm not having any doom and gloom - with a little care and attention pots are perfect for all plants.