Pots & Plants
Posted by Phytopath on Feb 26, 2011
Gardeners frequently grow plants in pots or containers for two main reasons; convenience and necessity.
Plants growing in pots are easily moved or transported.
Retail nurseries nationwide can purchase young plants in tubes (from wholesale nurseries), known as tube stock, then pot them up into larger size pots and sell them to the public.
The public can then purchase these plants and transport them home.
The plants can then be planted into a more ornamental pot or container, or planted in the garden, or more frequently, left at the back door to be planted ‘later’.
This typical behaviour leads to a collection (sometimes rather large) of various sized pots in the garden shed. We don’t always dispose of the pots either – just in case we need to use them later.
I don’t know about your garden shed, but in the dark of my shed, behind closed doors, my pots breed.
I’m sure I didn’t have that many pots last season.
Because of the portability of pot plants, they can be moved to a better growing environment through the seasons.
Cold sensitive plants can be moved to a warmer spot or indoors during the winter and sun sensitive plants can be moved to shade during the heat of summer.
Potted plants can also be utilized in office blocks and business premises to create an atmosphere of well being.
These indoor plants need to be rotated or replaced on a regular basis for the health of the plant. Growing plants in pots makes this more convenient for the business responsible for plant hire.
Convenience is also a factor for people who like gardening but are limited to a balcony garden or rental premises. Plants grown in pots are portable and convenient for both of the above situations.
Potted plants are also a great way to make a temporary display of colour or patterns. This is used by retail nurseries to display certain plants that they want to move or sell quickly.
It is also used in garden shows or gardening events where landscapers and garden designers erect a temporary display for the duration of the event.
The other reason people grow plants in pots is necessity.
The first example that comes to mind is pH.
If you live in an area where the soil pH is very high or alkaline, you would have a hard time trying to grow azaleas, rhododendrons and most berries.
The ability to purchase bags of potting mix specifically prepared for these plants, (low pH) would allow you to grow them in pots when otherwise it would be impossible.
Bonsai is another example. Growing trees in small containers allows you to control the growth of the plant.
Large scale commercial growers also recognise the benefits of pot culture to manipulate flowering times of container grown plants.
Temperature, humidity and light can be controlled in the growing environment, so that potted plants are ready for sale at optimum times of the year for profit e.g. Valentine’s Day and Mothers Day.
Some important points to keep in mind when considering growing plants in containers are:-
- The shape or height of the pot
- The material the pot is made of
- Drainage holes (size & number)
- The potting mix or media
In some cases, the shape of the pot may determine if the plant grown in it lives or dies.
Here is an example.
Take two plants that are identical in every way i.e. size, age shape etc.
Place one in a shallow pot and the other in a tall pot.
Potting mix and watering frequency are to be the same.
The plant growing in the shallow pot will suffer from root rot but the plant growing in the taller container will be fine. (Note: the reverse of this will happen if the watering frequency is low i.e. the plant grown in the shallow container or squat pot, will survive, and the plant growing in the tall container may die) 
The reason for this is: the water level of a saturated medium (just watered pot plant) is the same no matter what height or width the container is.
Try this by hanging two bath towels on the clothes line – one horizontal and one vertical.
After a wee while, check the dampness of both bath towels.
The damp area on both towels will be at the same height from the bottom of the towel regardless of which way they were hung.
The material that the pot is made from is also important.
Terracotta pots and unglazed pots dry out quicker in warm climates and black plastic pots hold a lot of heat around the root zone in hot climates.
For plant health it is best to match the plant to the pot, allowing for climatic and micro-climate conditions.
Plants should not be grown in a pot or container just because it ‘looks pretty’.
The third important point for pot growing culture is the medium or soil that is used in the pot.
I will cover this in another blog post.
Taking plant cuttings
Posted by Phytopath on Feb 13, 2011
It is almost my favourite time of the year.
I just love autumn. The deciduous trees colour up before losing their leaves.
The days are still warm but the nights start to get colder, but best of all, it’s the best time to take cuttings.
From late February until early May, semi-hardwood cuttings (Northern Hemisphere) strike the best.
The best material for taking cuttings, has high carbohydrate levels and low nitrogen levels.
To test this, use the ‘snap test’. If the piece of stem cutting snaps when you bend it rather than just bend, then it has low nitrogen levels and would have made a good piece of cutting wood until you just broke it. (she laughs)
The next selection criterion is the age of the stock plant.
Cuttings form roots much quicker when the material is taken from a young plant. Cuttings taken from older plants do not form roots as readily.
The area on the stock plant where the cutting is taken from is also important.
As a general rule, lateral growth (side shoots) is better than terminal growth (shoot tips). The lateral growth can often be removed with a heel. This provides a larger surface area for roots to develop from.
The size of the cutting will depend on the individual plant and how far apart the nodes are along the stem.
For small plants whose nodes are close together, a typical cutting would be 35mm to 60mm. Larger plants may need the cutting length to be 60mm to 80mm. But if you are taking cuttings from a plant like the Tree Dahlia – well, the nodes can be as much as 40mm or 50mm apart, so the cuttings will be quite long.
Non flowering material is best. If the plant has not quite finished flowering – wait for it to finish. If it is just starting to flower, forget about taking cuttings until flowering has stopped.
The time of year that you would take a cutting, is specific to each species of plant. Try a few cuttings throughout the seasons and see which works the best.
Time of day can also be important. Cuttings should be taken in the shade or on a cool day, not in the heat of a warm afternoon.
Make sure your secateurs or cutting implement is sharp and clean. Hygiene is important in the propagation area.
If you cannot deal with the cuttings immediately and need to store them for a while; wrap the cuttings in damp newspaper rather than leaving them in a plastic bag.
Root promoting hormones can be applied to the end of the cutting if you are not certified organic. The most common are IBA (indolbutyric acid), IAA (indoleacetic acid) and NAA (napthaleneacetic acid).
These root promoting hormones can be purchased as a liquid, gel or powder. If you are a bit clumsy, use the gel.
Local rose growers tell me they have great success with rose cuttings after soaking them in a bucket containing a solution of water and Willow twigs and leaves.
The environmental conditions where the cuttings are housed, is also important.
Moisture levels and humidity levels need to be correct for the species being propagated.
Temperature is also important and for most plants grown in warm temperate regions, the day temperature should be around 21°C to 27°C and the night temperature between 15°C and 18°C for best results.
If you can provide bottom heat near the base of your cuttings and ensure that the difference in temperature between the root zone and the air near the top of the cutting is around 10°C, then you will surely have success.
One last thing – make sure you put the cutting in the pot, the right way up.
