Growing Plants In Containers & The 7 Mistakes Everyone Makes
Having no containers in your garden is like having a sofa without cushions or a window without a view. Here are the 7 most common mistakes everybody makes when growing plants in containers.
1. Choosing the wrong Container
Size: Choose a container that will look right in the space you have.
Shape: Tall plants catch more wind and can blow over damaging the plant and worse still breaking the container. Choose a container with a wide base. Having more weight at the bottom will reduce the chance of it blowing over.
Material: Whilst stone planters look amazing and can be expensive they are very, very heavy. If you plan on moving the container then choose more lightweight material. There are some great recycled plastic containers that have slate or stone effect yet even 50 litre containers weigh less than 5kg unfilled.
Frost: Make sure your planters are frost proof and won’t disintegrate with frosts and U.V light from the sun.
2. Poor Compost Choices
For longer term plantings of shrubs always use the best compost you can find. Choose a soil based compost which is heavier to help with stability in strong winds.
Soil based composts do not tend to dry out so quickly as peat or coir based composts meaning less watering. This also helps to keep your plants watered throughout even hot days.
Thirsty plants do not grow so evenly, producing less flowers or fruits. They are also more prone to pest and disease when under water stress.
For acidic soil loving plants such as Rhododendrons and Camellias always use Ericaceous Compost which has the correct soil pH and nutrients for the plant to thrive.
3. Not Feeding
Yes, your plants do need feeding to grow. In many ways nurture a plant like you would a human or pet without having to treat it to trips out to the zoo or park.
When a plant is containerised, feed from the surrounding soil or rain water which carries nitrates does not get to the roots.
There are many types of feed on the market. Feeds are available as organic or non organic and both are available in granular or liquid form. I sit very much on using a bit of both in my garden.
In my beds and borders I use a mix of organic (Fish Blood and Bonemeal) and Non-organic Growmore along with mulching with my own compost from my compost bin.
However, my patio containers do usually get a teaspoon of slow-release granular fertiliser added on planting and as a top dress feed every spring to my permanent container plantings. This low application rate of feed releases for 6 months as the plant needs it. It avoids having to use any other feed and makes it simple. Applying once a year and it's done!
I’d rather do this than having to remember to add liquid feed once a fortnight to the watering can.
In the height of summer, I do occasionally liquid feed whilst watering for a little more flower power especially on my fruiting crops and summer bedding.
4. Not choosing the right size of container
Always start off with a container that is larger than the plant you have now. Whilst containerised plants will only grow to as much root space they have a large shrub can be kept smaller with regular watering and trimming.
By using a patio container that is smaller than the plant you’ve bought is not wise as simply you won’t get the plant in. It’s a bit like buying a pair of jeans that are 2 sizes too small. They simply won’t fit. The plant ballons from the top of the container and looks like it will fall out at any moment. You won’t have enough space to water the container either. The water will simply run off the sides.
5. Watering; Too much or too little
This is probably the toughest subject. How much water a plant needs depends on many factors.
What type of plant is it? Where would it naturally live? What type of compost has been used? Is it windy? Is it in full sun? Is it actively growing? Has it rained?
To answer most of those questions the answer is learn by experience.
I look at the plant, does the plant look droopy – maybe too much water. Droopy with shrivelled leaves and /or a dull finish to the leaves might mean too dry. The easiest way of all is to touch the compost with your fingertip.
If it is too dry your finger will feel dry soil and also no soil particles will stick to your finger.
If the soil is too wet then it will feel wet and particles will stick to your finger. Look at the soil, does it look dry?
Pots should always be filled leaving 2cm (1in) of gap between the soil and the top of the planter. This allows you to add water to the surface without it spilling out.
Drainage holes allow water to drain out if you’ve watered too much. (be careful with indoor plants as the water could stain your carpets or furniture)
Over the course of the following days and weeks touch the soil surface and you’ll begin to gauge and learn to water or not to water.
In winter outdoor containers rarely need watering in the UK. Long spells of bright yet cool days plants can actively grow. At times you may begin to notice that they look visually thirsty so water sparingly. Sitting in cold wet water is not ideal - a bit like us sitting in a cold swimming pool is not pleasant.
When it rains, apart from in winter, usually there is not enough rain to penetrate the canopy of the plant for the rain drops to hit the soil surface within the container to make any real difference in summer. So check the container daily even if it has rained.
I’d say you can do more damage by overwatering than under-watering. You can visibly see under-watering on a daily basis. Water more, twice a day, pot up into a larger container etc. But overwatering is a slow death for the plant and not so instantly visible.
6. Drainage Holes.
Drainage holes help you to not overwater. Most garden plants apart from aquatic plants do not like their roots in water. Roots breathe and to do so the soil needs to be moist yet not saturated otherwise they effectively drown. Starving the plant of the nutrients it needs for healthy growth. Root rot can set in, possibly killing the plant in the long term.
Drainage holes are simply holes in the bottom of the container which allow the excess water to escape. Some containers have them when you buy them. Others do not and this could be so the container can be used indoors and not leak onto your furniture.
Some containers have a raised section in the bottom of the container. This then ensures excess water can drain out but there is a little reservoir right at the bottom to help keep the plant moist when needed.
Drainage holes can be easily drilled into plastic containers. Using a drill bit slightly thicker than a pencil is large enough. Drill 4-5 holes around the container base.
If the holes are too big it is a good idea to add some gravel or crocs (bits of old broken terracotta pots when these were the main type of patio container available) into the bottom of the container as this will stop the soil leaking out a too big a hole.
In winter a good tip for your Mediterranean plants like Olives, Lavender and Palms which really dislike cold wet feet is to use a pot stand or pot feet or simply some pieces of wood to lift your container off the ground. A centimetre (1/2in) is enough to allow the water to drain away more easily and help keep their feet (a plant's roots) drier.
7. Not planting a container at all
The 'pros' of utilising containers are numerous;
- Containers decorate your garden. They make your garden come alive with shapes and textures.
- They allow you to raise the height of a plant so it can be seen.
- It allows you to grow herbs by your kitchen window.
- You can create fresh inviting displays to welcome you to your home.
- A colourful container can brighten up a dull area.
- Containers of plants can fill the air with perfume.
- Attract and feed beneficial insects.
- Plants can reduce noise pollution
- Plants create a calming environment.
- Provide mental and physical stimulation.
So now you know all the common mistakes to avoid, go ahead and put my tips to use and reinvigorate your existing containers or venture in to the world of container plants for the first time and enjoy transforming your garden with confidence.