Dry Tropics Biodiversity Group Inc.
(inform, educate, enthuse, implement)
to education and awareness main page
Buying plants, local and native.
see also conservation value of "local gene pool plants"
How to buy & establish plants:important: plant newly purchased plants immediately | purchase what size pot | how tall should plants in pots be | protect new plants in full sun | the first weeks of establishing plants | watering frequency | how long for full plant establishment | plants sitting in a "pond" after rain
The best advice is... put newly purchased plants into the ground quickly, especially if in small tubes.
Whether tubes or larger pots, put plants in the ground the day after you purchase them. But primarily do not underestimate how often they need to be watered. There are other factors too, so as soon as possible plant in the ground.
What size pot plant is best to buy
All pots require care, but never forget that plants in native tubes require a little more care (see below).
Native tubes (5cm square opening, 12cm long) are best value for money, but only if you care for them better.
You get more plants for the same money, and they catch up and pass the bigger potted specimens in time, providing they are cared for properly and were not rootbound. The cost sensitive tough professional revegetation environment virtually always uses native tubes. Only a narrow range of plants can be stocked in tubes.
14cm standard pots grow very well. The widest range of plants are available in this size.
20cm (8") pots are especially expensive
usually only look more impressive for a short time after planting, but they require less after-planting care.
When purchasing a plant.. how tall should my plant be?
- Different people have quite widely divergent opinions. Contrary to popular opinion, research indicates that smaller foliaged plants are best. Given the same pot size, smaller foliage plants with a less dense rootball at purchase time will be much less work to establish in the garden, will produce the best root system and will grow quicker.
- But long experience with growing plants also shows that larger plants in the same size pot also grow very well. Larger plants have more immediate visual impact, and the difference in growth is usually not noticeable for landscaping. But they require much more care to establish successfully.
- Small shrubs and monocots (e.g. palms, lilies, grasses) do not get rootbound but still benefit from being smaller foliaged. Especially trees and larger shrubs should not be rootbound. "Rootbound" or "potbound" concerns roots that spiral around the pot, these later increase in thickness and grow tightly together so locking into other roots and suffocate the whole plant, these roots are weak and poorly withstand wind.
For commercial growers looking for maximum growth (trees and shrubs), research indicates an ideal height between one pot diameter and two diameters...
- 5 cm dia. x 5 high nursery tubes have an ideal foliage height 5-10cm
- 5 cm square x 12 high native tubes: 20cm is the maximum height accepted by Forestry.
- 14 cm dia. x 14 high standard pots have an ideal foliage height 15-30cm
But taller plants still grow almost as well for many purposes. In fact be sure to purchase taller plants when they compete with tall grasses, or if planting on creek banks where maximum plant size in one growing season is required to minimise flood damage.
- Particularly this is the case with revegetation planting.
- Move up to a larger pot size if becoming rootbound, or to reduce establishment work. The smaller foliaged plants will be shaded out or accidentally mowed if faster growing grasses cannot be controlled satisfactorily. Note that grasses are very competitive and must be removed from the close vicinity of young plants regardless of height
- But if in the same size root container, these taller plants are more sensitive to water shortage and take longer to establish in the ground.
Plants put in full sun should be protected for some weeks.
Prune leafy branches from elsewhere, bury them as stakes alongside new plants to provide partial shade and hot wind protection for at least half of the day.
- Over several weeks the leaves on the stake will shrivel and drop gradually exposing the plant to more and more sun. This reduces plant water usage. Leaves need time to acclimatise to different conditions.
- Temporarily protecting and partially shading newly in ground plants in open sunny positions helps greatly to establish plants that are not fully sun/drought hardened. Indeed for some plants survival is at risk. Regardless of what you are told, plants are seldom sun/drought hardened. Even if grown in full sun, the lower foliage of plants in nurseries is often heavily shaded and in higher humidity from adjacent plants. For very good reasons most nurseries cannot reduce water satisfactorily to drought harden plants.
Alternatively/additionally pruning foliage improves survival chances greatly especially if there is to be minimum maintenance.
Prune to encourage shrub form by cutting off the top half of the plant's foliage.
Prune to encourage tree form by removing all leaves from the base, leaving a leafy tuft at the top.
Watering plants in pots... the first weeks of establishing plants in the ground...
Most plants get forgotten, so suffer from too infrequent watering both while still in the pot and for the first few weeks after planting. Tubes generally need more frequent watering.
Nurseries aim to provide water more often than is absolutely needed, and so should you until they are planted in the ground. (drought hardening plants in potting mix successfully requires specialised knowledge)
Despite the rules of thumb below, make sure you water plants with more foliage more often. For all plants the potting mix should always be quite damp or moist just under the surface until establishment is well underway.
Plants use almost all water by evaporating it from their leaves. Twice the height with the same pot size and foliage shape can mean watering is required 4 times as often.
"native tubes" with more than 30cm tall, erect narrow shaped foliage must be watered at least twice daily... in the early morning and in the afternoon.
The only water available to the plant between watering is held in the potting mix. The larger the tube/pot the larger the reservoir. 14 cm standard pots hold 7 times the water of 5cm square x 12cm "native tubes" so even smaller foliaged native tubes require watering more often than do normally foliaged 14cm pots
14 cm pots with more than 30 cm height and rounded shaped foliage should be watered at least daily.
Watering frequency when in the ground
After a couple of days in the ground, providing the following conditions are fulfilled, decrease the watering frequency to twice weekly for tubes, weekly for larger pots.
- conditions to be fulfilled for plants not to suffer:
- the soil was initially very well loosened and totally saturated before planting
- plants in open positions in full sun are partly shaded and protected from wind initially
- plants have no more than moderate foliage
- These recommendations should ensure rapid growth and establishment of a wide variety of species.
- This information sheet contains general advice, properly hardened plants (need to be grown specially for the purpose) whose species are also very well suited to the natural local conditions can require far less looking after once they are in the ground.
How long does it take for full plant establishment in the ground.
after 1 month in the ground, double the interval between watering.
- It is wise to acclimatise plants to reduced water by gradually increasing the interval between watering interval after about 1 month in the ground. Then if watering is missed plants will suffer less.
- Growth of plants will be slowed, but this is usually best and encourages root development, plants bought in the August Australian Plants Expo. will then be ready to grow well throughout the wet season.
3 months after planting in the ground, ensure at least one deep watering per month
after 6 months watering should be at permanent levels
Plants sitting in a "pond" after rain
One word of caution... most plants cannot tolerate regularly "sitting in a pond" for more than a few hours or so, even if the "pond" is invisible underground around their roots.
Occasional flood inundation for a day or more is often OK, but not regularly.
Society for Growing Australian Plants, Townsville
By Doug Silke
top to education and awareness main page