The success of any revegetation project depends to a large extent on the successful production of vigorous young seedlings.
Seedlings used in revegetation are sometimes called “tubestock” because they are grown in small forestry tubes. In most cases, germination takes place between two and six weeks of sowing the seeds. There should be a white plastic label in one of the corner tubes, with the name of the plant species (scientific name followed by common name) on one side, and a description of where the seed was collected from and the date they were sown on the other.
Placement
In order to reduce the chance of pest and disease attack on you plants it is important to keep your tray(s) in a raised position with full air circulation underneath. Anything that will make it difficult for slugs, snails or ants to reach your plants, while allowing air to circulate underneath, and water to drain away quickly can be suitable. The best method is a raised steel-mesh topped bench.
Most native plants respond best to light shade in the early stages of their life. This can be achieved by keeping your trays under 50% shade cloth, or under the dappled shade of a tree. Alternatively, a position which receives morning and afternoon light, but which is heavily shaded in the middle of the day can be suitable.
Once the plants have germinated and are about 2cm tall they can be moved out into full sun. It may still prove necessary to provide them with light shade on particularly hot, sunny, windy days, but as a general rule the plants will require full sun for 6 hours a day. They should have no problems with this provided they are watered correctly.
Watering
While your plants are germinating it is very important that the soil is not allowed to dry out at all. If the soil does dry out for even a short period, many or all of the germinating plants could perish. It is also important that your seedlings receive regular watering during the early life stages, particularly during germination.
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A healthy seedling
ready for planting out at the
revegetation site
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The best way to deliver water to your seedlings is though a garden hose with a fine spray head, or automatic watering system with misting heads. Fine spray at low pressure is needed because excess disturbance of the soil surface (such as happens with a garden hose without a spray head, or coarse watering can) may either damage emerging plants, or wash seed out of the tubes.
Wherever possible water in the morning and the afternoon. If there is a period of exceptionally hot weather it may be necessary to water during the middle of the day if possible. Try not to water at night because if the seedlings and their surroundings are still wet as it becomes dark, slugs snails and fungal diseases will be encouraged.
Each watering should result in water percolating right through the soil, not just wetting the surface. It pays to check the bottom of a couple of tubes to be sure that the moisture has penetrated right through. Also, be sure that those tubes on the edges of the tray don’t get less water than those in the middle.
PLEASE NOTE that some species of semi-aquatic plants are grown by what is called the “Bog Method”. If your tray is lined with a piece of plastic sheet which prevents water from draining out the bottom, it is because the plants are being grown via this method. The idea is that the tubes are kept constantly “boggy” but retaining 2 – 3 cm of water pooled at their base. This mimics the sort of moisture conditions that such plants favour in their natural setting. Water can be delivered to these plants by pouring it between the tubes. Capillary action will then draw the water up through the soil to the germinating seeds. Care should be taken to keep the water level near constant.
Thinning
Because not all seed is viable, each tube in your tray will have had multiple seeds sown into it. This can result in several plants germinating in a single tube. The aim is to have only 1 plant per tube for planing out, so often thinning is necessary.
PLEASE NOTE: This is not necessary for Monocot (grassy) plants such as Juncus, Cyperus, Themida, Danthonia, Stipa, Carex, Gahnia, Bolboscoenus, and Scoenoplectus species.
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“Pricking out” surplus seedlings
using pointed scissor arm
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After a month or so, (or when most of the young plants have 4 leaves) if every tube in you tray has several plants germinating in it, you will have to thin them. This is done by removing all but the three strongest looking plants. Later, when the plants are 3-5 cm tall, you will remove the 2 smallest seedlings, leaving only 1 strong seedling per tube.
If you have had limited germination, where some tubes have several seedlings emerging, and some tubes with nothing, it is possible to carefully remove some of the smaller seedlings from tubes with many, and transplant them into the empty tubes. To do this you will have to “prick” out some of the smaller seedlings. Using a small screwdriver, the pointed arm of a pair of scissors, or something similar, carefully dig out a small seedling from a tube which has many. Take care to minimise the disturbance to the other plants in the tube.
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Use a pencil to ream a hole in
the soil of the blank tube
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Ream a hole in the soil of a tube without seedlings by pushing in a screwdriver or pencil 5 or 6 cm deep, then place the seedling that you removed in the previous step in the hole being sure to keeping the roots straight down.
Gently press the soil around the transplanted seedling and water in to further settle the soil around the roots. Keep the transplanted seedlings in light shade for 2-3 weeks after this procedure in order to settle them, then return to their original full-sun position.
Weeds
Unfortunately, it is not uncommon to have weeds germinate alongside your seedlings. This is minimised using sterilised potting mix and by keeping the trays raised. However, this does not completely prevent weed seed blowing or falling into the tubes. Once most of your seedlings start to germinate, you will quickly learn to tell when something a bit different appears in one of your tubes. It’s a case of spotting the odd one out.
Any weeds observed in your pots should be carefully removed by gently pulling them out, bringing the roots out if possible. As with thinning, be careful to minimise the disturbance to any nearby seedlings also in the tube.
Damping off
This is a term used to describe a condition that sometimes affects young seedlings. It is caused by a fungus which is encouraged by warm damp conditions. The symptoms can include wilting and blackening (rotting) of the stem. If damping off starts to occur, immediate treatment with a soil fungicide is required. Fungicides are available cheaply, and are often applied by mixing the chemical with water and applying with a watering can. The chance of damping off can be minimised by allowing good water drainage and air circulation under your trays.
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