All Planters Aren’t Created Equal!

Looking at micro gardening in a pot?  If you are confused about what kind of pot or container to choose for your plants, you’re not alone!  There are the good, the bad and the ugly out there …

Choosing a pot - depending on your needs, values and budget, there are a range of choices.

Compare the different options before you decide on your plant container – it may save you time, money and help the environment.

 

A few points to consider:

  • Financial Cost: There are lots of options on the market if you are looking to buy – from cheap and cheerful to decorative and expensive.
  • Product Life: Think about the longevity of the pot you require. Is it for a short term project? If so, looks may not be important. Or is it something you’re prepared to invest in, as a design feature?  Extended durability can mean less consumption of resources.
  • Environmental Impact: Some planter materials and construction processes drain our natural resources. Others have a smaller environmental footprint using less resources. Processes used in manufacture and transport often require significant use of fossil fuels. As a ‘conscious consumer,’ is this important to you? If so, consider making your own pots where possible. Choose pots made from sustainable materials or reuse containers creatively to grow your plants.
  • Time & Energy: If you have limited time, you may want to buy a planter. However, making your own by repurposing a wide range of containers into practical planters, is much easier than you think.  See Repurposed Planters for loads of creative and inspiring low-cost ideas.

 

Basil growing in repurposed tin can planters. Photo: Dov Harrington

Basil growing in repurposed tin can planters.

  • Pros & Cons: You may want to consider some of the advantages and disadvantages of various types of containers before you put your hand in your pocket and go shopping!
  • Your particular situation – there are three key factors which may also influence your decision on which kind of pot to choose.

 

Pros & Cons of Containers Comparison Chart

Here’s a comparison tool I have put together that may help make your decision easier.

 

Pots & Containers Advantages & Disadvantages
Plastic pots (light coloured)

Relatively inexpensive plastic pots with fruit trees.

Lightweight plastic pots heat and cool quickly and minimise root damage in hot weather.

  • Generally cheap. Often available for very low cost from recycling centres or garage sales.
  • Heat and cool quickly so plant roots and microorganisms are not damaged as easily even when in a sunny location.
  • Generally have more drainage holes than terracotta, ceramic and concrete pots.
  • Easy to drill additional holes in base if needed.
  • Lightweight, so suitable for balconies and decks where weight is a consideration.
  • Come in all shapes, colours and sizes, are made from a variety of different plastics and can be spray painted if desired.
  • For younger children, they may be a safer alternative to the standard breakable clay pot.
  • They keep the moisture in but don’t store any reserve themselves, unlike ceramics and terracotta.
  • However, plastics are petroleum based products. They drain our natural resources so consider the environmental impact – there are other more sustainable choices.
  • There are also health issues associated with some plastics – if you are using plastic pots, try to use the least toxic ones (#2 HDPE, #4 LDPE, and #5 PP) and avoid #3 PVC, #6 PS, and #7 polycarbonate.
  • Current research seems to indicate the majority of plant pots are made from polypropylene (#5 or PP – currently one of the safer plastics) however it’s better to check than assume.
  • The Environmental Working Group (a very useful resource for those concerned about health and toxics in our environment) also recommends discarding scratched or worn plastic containers to avoid leaching of chemicals.
  • They do not tend to last more than a few seasons – as with most plastics, sunlight gradually degrades them and they become fragile. If using them, look for the thicker ones for durability. Keep them under cover when not in use – they’ll last longer.
  • Once broken down, it may be challenging to find a way of reusing them so consider the environmental impact at the end of their life if they have to end up in landfill also.
  • If you want to change your current plastic pots for another alternative, consider taking them to your local recycling centre; or donating them to a community garden or local nursery and perhaps swapping for some free plants or cuttings in exchange.
Black plastic pots
  • Heat up quickly and provide little insulation.
  • Avoid using in full sun but OK to use in shady positions.
White Polystyrene (foam) boxes

(Food grade) – also known as EP or expanded polystyrene boxes

Painted polystyrene box

White polystyrene boxes can be painted to make them more attractive as micro gardens

  • Provide great insulation – have excellent thermal properties.
  • White colour reflects light/heat so helps insulate plant roots – useful in hot climates.
  • Cheap (usually free) from greengrocers.
  • Easily available – most greengrocers, supermarkets and fish mongers are happy to offload them rather than pay for them to be taken away to landfill.
  • Useful for when visual appeal is not a priority – or just paint/decorate them!
  • Deep (like broccoli boxes) provide some level of insulation but shallow boxes can get hot.
  • Good drainage – most boxes (with the exception of a few sizes including the deeper broccoli boxes) also happen to have great drainage holes.  If not, you can easily make your own holes.
  • Lightweight – easy to transport and stack.
  • Durable – they are stable and last well even in hot sunny climates.
  • Easy to clean – just need a wipe down with a wet cloth or hose.
  • Come in a variety of sizes and depths – you have a great choice with polystyrene boxes so you can choose which best meets your particular needs.
  • Not particularly attractive – OK if this is not an issue although they can be painted to suit your tastes.
  • Reusing these boxes helps keep them out of landfill and is kinder to our environment.
  • If they start to degrade or become damaged, do not use them.
Terracotta, ceramic and concrete pots that usually only have one hole in the base.

Terracotta pots with herbs may need more watering as they lose moisture in hot weather.

Clay pots are porous but breakable and have a lot of pros and cons to consider.

  • These materials generally offer more visually appealing options in terms of colour and design.
  • Provide inadequate drainage for most species of plants.
  • You have to drill additional holes in the base without breaking the pot!
  • Lightweight terracotta pots tend to be more breakable and chip easily.
  • Prone to cracking when soil freezes and expands in cold-weather zones.
  • These materials retain heat for long periods – whilst some species may benefit from this, the potting mix can become very hot in sunny positions, killing microorganisms and burning plant roots.
  • These materials are porous so draw moisture from the potting mix and dry out more quickly.  Plants require more frequent watering (higher maintenance).
  • Re-potting can be a major challenge to avoid breaking the pots.
  • Ceramic pots that are often curved in shape at the top make it difficult to repot or change the potting mix.
  • Glazed ceramic pots tend to be heavy and are waterproof so hold moisture better.
  • Terracotta is widely available, there are a large variety of shapes and sizes to choose from and the basic unglazed clay pots are not expensive.
  • Unglazed clay pots are perfect for children to paint.
  • They absorb mineral salts and may produce a white crusty build-up on the outside.
  • Clay pots are breakable, and the chards can have sharp edges, so not necessarily a good idea for very young children.
  • Plants put directly inside terracotta and cement pots can stain the outside from the salts and minerals in the soil and water.  This can be avoided by painting the inside and bottom with a coat of non-toxic waterproof paint.
  • They are bottom heavy (weight is generally at the base) so suitable for windy sites.
  • Concrete planters come in much larger sizes so are suitable for large shrubs and trees but their additional weight may be a consideration in some situations.  If this is the case, faux concrete products may be a better option as they are more lightweight.
  • There are a number of environmental issues associated with concrete products.
  • Concrete is a good insulator so suits climates with severe changes in weather because it helps buffer plants and soil from extremes in temperature.
  • Concrete is porous so may need sealing and should be properly cured to avoid impacting the soil alkalinity.
  • Concrete is high in lime which is toxic to many plants.  Prior to use, water the pot or trough thoroughly several times and allow the water to drain away each time so excess lime dissipates.  Alternatively, allow the concrete planter to sit outdoors in the rain for several weeks so lime can leach out before planting.
  • Clay has been used for thousands of years and is generally considered to be a sustainable resource.
Stone containers

Stone containers often suit feature plants that make a statement.

Stone containers are solid and stable.

  • Some old planters made of natural stone have loads of character, look attractive and very ornamental but tend to be very expensive and heavy.
  • Reconstructed or faux stone containers are cheaper and quite widely available in different sizes and styles.  They are also more lightweight.
  • They are solid, have good heat insulation and last a long, long time.
  • Given the embodied energy used to produce these containers and their long life, they are one of the more environmentally friendly choices.
  • Genuine stone ages beautifully with changes in colour.
  • Breakable and heavier to move around.
  • Many stone planters are made from a mix of limestone and lightweight fibreglass so they are more manoeuvrable, durable and waterproof.
  • Production processes for faux stone planters simulate textures and patterns on natural stone so they are very difficult to tell they are not the real thing!
Self-watering pots

Self watering pots cut down time spent watering

Self watering pots usually have a reservoir system in the base

  • Unsuitable for large plants like fruit trees or shrubs as roots work their way into the water reservoir at the bottom, leading to water logging and diseases.
  • More suitable for hanging basket situations that receive ventilation and are likely to dry out quickly.
  • Are usually lightweight so may be useful where pot weight is a consideration.
  • Plants that can cope with ‘wet feet’ may be suitable for these types of pots including indoor varieties like Spathiphillum (Peace Lily) and some ferns.
  • Be careful to remove the ‘plug’ at the bottom of the pot if using in an outdoor area that is open to rain or else the pot will fill up and drown.
  • Handy for people who are busy, away a lot or forgetful gardeners.
  • Contain a hidden reservoir that you fill with water and a wick or delivery system to filter it up to the plant.
  • Useful for smaller plants that may have to be watered more than once a day.
  • Helpful in situations where space is limited, hard to reach places, hanging baskets with higher maintenance needs or groups of plants where some pots are at the back and hard to water.
  • Can be more expensive for the initial outlay but benefits may outweigh this cost.
  • Help reduce the frequency of plant waterings but won’t eliminate them!
  • Again, these containers are most often made of plastic so consider the environmental impact of this choice.
Hanging & wall mounted baskets

Tiered hanging baskets make use of vertical space

Hanging baskets help make the most of vertical space and can provide shade and privacy.

  • Generally inexpensive to buy, the framework is usually made from plastic-coated wire which makes them light and rustproof.
  • When heavily exposed to the weather they can heat up and dry out quickly.  Keep away from windy positions to prevent rapid drying of the soil which can cause extreme damage to the plant’s root system resulting in a plant fatality or one that has poor foliage and flowers.
  • For long term rust prevention and to make them both attractive, some baskets are powder coated inside.
  • Available in a wide variety of materials including coconut fibre, synthetic, wrought iron, coated wire and metal that come with natural liners often made out of coir (coconut fibre) or sphagnum moss.
  • Consider the material they are made from – where possible choose natural fibres and sustainable resources which are not detrimental to our environment.
  • Some liners are made out of recycled plastic bottles and are porous with a looser weave – however if you are considering growing food, consider the safety of growing in recycled plastics which may leach toxic chemicals into the soil.
  • After watering, water may drip out the bottom onto another surface so need to be located above other plants to maximise watering or positioned over a surface that does not matter if it gets wet.
  • Available in self-watering designs with a water reservoir at the bottom, reducing the frequency of watering needed.
Wooden window and planter boxes and containers

Wooden tub of herbs

Wooden containers are usually attractive but have maintenance and environmental issues to consider.

  • Usually light-mid weight depending on the dimensions of the planter and type of wood.
  • Add heaps of character and are available in a wide variety of timbers and colours.
  • Are very functional when combined with other garden features like bench seats, trellises and storage.
  • Can be painted or made with pressure-treated woods, for a longer useful life.
  • For food safety, you will need to check which chemical preservative treatments have been used or whether it needs sealing before being used as a container for growing edibles.
  • Not all preservatives are bio-friendly. Older wooden containers may have been treated with chemicals such as CCA which leaches arsenic into the soil, kills insects and is unsuitable for food crops.  There are safe alternative timber treatments available for DIY timber preservation but there is additional cost and time involved.
  • The timber used may not be from a sustainable resource.  Look for companies creating products from sustainable timber plantations or bamboo.
  • Can be bought both ready made and finished, or as DIY kits.
  • They are very attractive, provide good heat insulation for the soil and can be easy and cheap to make to the exact size you need.
  • Help insulate plant roots from the sun and too much heat.
  • Sometimes the wood can split, or the metal bands (in the case of a half-barrel) or nails can go rusty and weaken the structure.  Use rust proof nails if making your own container.
  • Timber is a natural resource so some pest insects may take up residence.
  • Container bottoms may rot if they get too moist so they need to be elevated and have adequate drainage.  Portable trolleys with castors are a good option for wooden pots and also help with mobility for heavy tubs when filled with soil and plants.
  • To avoid timber rotting, put another pot inside a wooden planter (use as a cache pot) and use only for external decoration or line with heavy duty black plastic with drainage holes.  If using black plastic, avoid planting edibles due to possible chemical leaching.
  • Relatively durable and unlikely to break, they stand up to the cold well.
  • Usually a good choice for larger container gardening projects, and one which is easy to paint and add that personal touch to.
  • Do require maintenance with a preservative treatment every year or so.  Treat wooden planters with a non-toxic stain, paint or a waterproofing agent.  Oil can also help preserve the timber and keep it from drying out.
  • Untreated wooden planters will lose their visual appeal and eventually rot in time.
  • Rot resistant timbers like redwood and cedar don’t require painting.
Metal containers

This metal tub of pansies is positioned in a sheltered spot so it won't cook the flowers!

Metal containers can add character but be aware they heat up too if in direct sun during hot weather.

  • Are usually attractive and very decorative.
  • Are durable – won’t chip, crack or break.
  • Provide little insulation and heat up rapidly which causes the soil to dry out and increase the possibility of root damage. Use some form of insulation such as a clay or plastic pot liner.
  • Avoid the old-fashioned toxic lead planters if you have small children or you want to grow vegetables.
  • Often used as ‘cache pots’— decorative containers which hold a plant in a plastic or less attractive pot inside – also prevents the heat from directly affecting the plant roots.
  • Most metal containers will age gracefully with an aged patina or beautiful colour, although depending on the type of metal, some will rust.
  • Metal is non-porous so drainage is a major consideration.  Make sure you are able to drill adequate holes in the container.
  • Weight may be a consideration depending on the type of metal.  Cast iron is particularly heavy and may not be suitable for balcony gardens or apartments – check the weight tolerance first or position around the perimeter of the balcony where there is more structural strength.
  • In wet regions such as humid sub-tropical or tropical areas where heavy rainfall is common, outside metal planters may require the addition of a non-toxic rust inhibitor to prevent deterioration in the weather.  Otherwise, to keep metal containers looking their best, consider locating them under cover.
Grow bags

Grow bags with potatoes

Grow bags are cheap and lightweight and easy for renters to pick up and move.

  • A relatively new concept for the domestic market, grow bags are strong and very cheap considering the volume they hold.
  • Are lightweight and many have handles so are easy to move.
  • Are UV resistant (usually made from woven UV treated polypropylene) which makes them quite durable.
  • Very compact – they fold up like a shopping bag so easy to transport and due to their flexibility, makes re-potting easy.
  • Have good drainage holes and are strong so can take a wide variety of plants from shallow veggies and herbs to trees.
  • Come in a variety of sizes, colours and shapes.  Generally green is the most popular colour but they can be put inside another decorative cache pot if desired for aesthetics.
  • Can lean a bit if the soil potting mix is not well watered in.
  • Generally regarded as a temporary home for plants.
  • Particularly suit renters who need a portable garden when they move house.
Upside-down grow bags

Tomatoes growing in an upside down tomato planter

Upside down planters are a popular space saving growing system particularly for edible plants like tomatoes.

  • They are specifically designed for food crops such as tomatoes and potatoes but can be adapted for other plants too.
  • Small amount of space required as they hang from a hook so no floor space is needed.
  • They are usually ornamental and attractive.
  • Because the soil system is open on the sides on a hanging planter, it can warm much quicker than with plants grown in the ground.
  • Less likely for weeds to grow and easy to mulch.
  • The chance of soil borne diseases is reduced as the soil does not splash up on the plants when they are watered.
  • Less likelihood of disease problem as there is better air circulation around the plants when hanging.
  • No support system such as cages, stakes or tying required – plants simply hang down with gravity.
  • Heavy weight due to the large volume of potting mix in these planters.  After water is added they can get too heavy to carry or hang.
  • The size of the bag has to be relatively small so it is light enough to carry and hang so the root system is smaller than a tomato plant grown in the ground. Smaller determinate varieties of tomatoes for example need to be selected rather than large ones that won’t grow well in these conditions.
  • The root system is exposed to evaporation on several sides so in the warmer summer months you may need to water daily to keep a large tomato plant going.
Cachepots or double pots (e.g. wicker baskets and decorative containers)

Attractive cache pots with pebble mulch

Cache pots are a popular way to use a decorative outer pot to hide an inner ugly one!

  • Decorative ornamental containers used for holding and concealing ordinary cheap or unattractive grow pot(s) – often flowers but can be used for any plant.
  • Slightly larger containers – Ideal for temporary displays of potted colour or for positioning plants in less than ideal locations e.g. sun-loving flowers in a shady spot or indoor table decorations.  This concept is suitable for rotating plants from indoors back outside for a short period and then returning them to the cachepot.  Cyclamen flowers are a good example.
  • Potted colour (e.g. flowering annuals like pansies) can even manage to flower for a short period in temporary shade.  Just rotate from sitting in a cachepot in a shady spot and move to a sunny position every few days.  Swap with a replacement pot of flowers and then reverse so flowers are not deprived of sun for too long.
  • Aesthetic value – cachepots give the plant a “finished look” – Plants can be replaced if you don’t like the look or the way the plant is performing.
  • Suitable for testing whether a plant will do well in a position without having to re-pot it permanently.
  • Plant and the roots are not disturbed, no mess to change the look and no heavy pots to move around.
  • Pots without drain holes can be used and cachepots can hold a saucer for excess water that drains out of the grow pot.
  • If the decorative cachepot is too tall for the interior grow pot, a piece of Styrofoam in the bottom of the cachepot will raise the plant and assist drainage.
  • Usually unsuitable plant containers such as lightweight, inexpensive and attractive woven baskets can be lined with plastic and become cachepots.

 

At the end of the day, all containers have pros and cons – next time you’re considering buying, repurposing or making your own container, hopefully these guidelines will help you make a better choice.

Still want more information on pots?  Check out some Tips for Growing a Garden in Pots, 5 Thrifty Recycling Ideas for making your own and consider the Benefits of Using Repurposed Planters.  You will also find a lot of tips in the Container Gardening category.

Did you find this information helpful?  Feel free to share your thoughts and experiences with containers you have used … the good, the bad and the ugly or leave a comment below.  Keep up to date with new posts by subscribing to my newsletter (and grab your free eBook) or click on the RSS feed below or to the right.

 

© Copyright Anne Gibson, The Micro Gardener 2010-2013 – http://www.themicrogardener.com. All rights reserved.