Do show your appreciation by keeping a link to iRedlof. You can put anything you want in this sliding panel: like a post, videos, image, anything you feel like.Open iredlof_ajax_login.php and modify line no:151
With winter approaching it is time to look at ways to lessen the damage that very cold weather can cause.
What happens within the plant?
It is when the temperature falls below freezing that plants are most likely to be damaged. Some of the water contained within the plant cells flows out the cells to the spaces between the cells and freezes. When the temperature warms it melts and moves back into the cells without causing too much damage (provided it caused no bursting of any of the plant’s parts). Although the dissolved salts within the plant cells act as the plant’s equivalent of anti-freeze and lower the point of freezing, if it gets cold enough the water within the cells also freezes. When this happens the ice crystals damage the cell walls and as the crystals melt the cells dry out and die off.
What climatic conditions lead to cold damage?
Air may be invisible but it flows in the same manner as water. Cold air, being dense and heavy, flows and settles closest to the ground. If the flow of cold air is slowed down or stopped by walls, fences and hedges it will begin to flow upwards. Because the coldest air is closest to the ground it initially causes damage to the lowest parts of the plant but over time the damage systematically moves up the plant.
Wind exacerbates cold damage; this is because it reduces the temperature on the surface of plants through evaporation. Windbreaks can prevent this additional damage but they must also be designed in such a way that they don’t trap cold air.
What can a gardener do?
Gardeners in cold climates are not totally helpless – there are ways to fight back!
• Pick the right plants – choose plants suitable to the climate and micro-climate of your garden. Endemic plants, for example, will stand a much better chance against the cold than exotics from more temperate climes.
§ Keep them healthy – plants that have had timely treatment against diseases and pests are better able to withstand cold weather.
• Good feeding – apply the correct fertilizers in spring and summer and stay away from nitrogen-rich fertilizers in late autumn. Nitrogen stimulates new growth, especially during sunny days, so should rather not be applied after March.
• Leave the leaves – dense foliage prevents heat loss so don’t prune tender evergreen plants in late autumn or winter and don’t cut away dead plant material, unless it is very unsightly. It is also best to delay winter pruning as long as possible because pruning stimulates new growth (most especially in unexpected warm weather) and new growth is most susceptible to frost damage.
• Cover up with mulch and fleece – organic mulches are the ideal protection against water and heat loss from the root area of plants. By preventing the loss of these two elements microbial activity can continue and this, in turn, generates heat. Protect vulnerable plants with horticultural fleece or frost cover, or by making enclosures around them using plastic (keep the tops open). The roots of plants in containers are especially susceptible to cold damage so pack the pots and planters closely together and cover them with hessian or grass.
• Moist soil helps – because it cools down at a slower rate than dry soil. Ensure that your plants never dry out and make a point of watering well when a cold front is expected. Watering at daybreak before the sun’s rays reach frozen plants will help them to defrost slowly thus lessening the damage – provided the air temperature rises above freezing point. Change your summer irrigation programme from April – you can still irrigate for the same length of time per session, but gradually increase the time between sessions.
• Don’t plant now – avoid planting and transplanting perennial plants in late autumn as they are unlikely to have established themselves properly by the time the worst winter cold strikes. Ideally in the summer rainfall areas with cold climates it is best if planting only starts again in August.
There is nothing nicer than getting plants for free. One of the quickest ways to do that is to take cuttings -- this applies particularly to perennial herbs. Taking cuttings is one of the most reliable methods of propagation and it is also fun -- there is such a sense of satisfaction when the cutting begins to grow.
All you need is a clean knife or a pair of secateurs and as soon as the cutting has been taken, insert it in a damp growing medium, which can be well drained compost or a mixture of peat and sand. Warmth is needed for rooting and humidity is important for leafy cuttings. To create a mini greenhouse you can enclose the pot in a plastic bag.
Here’s the step-by-step approach to taking softwood cuttings that I use in my home study course, ‘How to be a wildly successful herb gardener’.
• The first step is to take a cutting with at least three leaves and a shoot. The best stems for cutting are the side branches or those near the base of the plant. Trim the stem just below the lowest leaf point• Have a clean pot on hand that is filled with damp, but well-drained compost. Make a hole with a dibbler or your finger, and insert the cutting.
• Gently firm the compost by pressing downwards and sideways towards the cutting (Picture 6 and 7).
• Water lightly
• Bend a piece of wire to form an arch over the cutting and press it into the pot. Cover with a transparent polythene bag. Another option is to cut the bottom off a 2-litre soft drink bottle and place it over the pot
• Place the cuttings in a warm area that receives good light but no direct sun
• The plastic bag or bottle traps the moisture and the heat inside, creating a mini-micro climate allowing the pot to be left for about 3 days without watering. Check every now and then to ensure that the soil is still damp.
• If it gets too humid in the bags it might be necessary to open them up during the day otherwise fungus could attack the plants.
Softwood cuttings should root within two to five weeks. Such cuttings are generally taken in spring and summer.
The cuttings taken in late summer or early autumn are usually from ‘half ripe’ wood. They will be firmer than softwood cuttings and should be taken from the side shoots of the current season’s growth. It is possible to put these cuttings straight into well-prepared soil but the soil must be kept moist and they must be kept shaded.
The best time or times to take cuttings, and the type of cutting to be taken during that season, varies from herb to herb.
The Artemisias: Wilde als (ARTEMISIA affra);
Mugwort (A. vulgaris);
Southernwood (A. abrotanum);
Wormwood (A. absinthium) -- take semi-hardwood cuttings in late summer.
Bergamot (MONARDA didyma) -- stem cuttings.
Feverfew (TANACETUM parthenium) -- stem cuttings.
Mints -- stem cuttings.
Sage (SALVIA officinalis) -softwood cuttings in late summer. Replace plants every four to five years.
Santolina (SANTOLINA chamaecyparissus) -cuttings, from midsummer to autumn.
Savory (SATUREJA montana) -- stem cuttings.
Spring and summer
Marjoram (ORIGANUM majorana) -- stem cuttings (late spring to summer).
Oregano (ORIGANUM vulgare) -- stem cuttings (late spring to summer).
Scented geraniums (Pelargonium species) -- tip cuttings (spring and late summer).
Thyme (all Thymus species) -stem cuttings.