I will not discuss the subject of climate change here as the Politicians and the ABC have said all there is on the subject, however I will tell you one thing and that is that you cannot fool Tomatoes, Capsicum, Basil and so on as they will grow when 3 basic things are available in correct quantities: light, heat and nutrient.
This year the condition of light and warmth has been lacking as everyone has experienced to date and so this brings me to the subject of how to grow Capsicum in a climate which is not ideal for this cultivar. In general terms Vegetative temperatures would be required to be in the order of 18⁰C – 20⁰C (night) and 20⁰C – 22⁰C (day) and Generative temperatures 18⁰C – 20⁰C (night) and 22⁰C -25⁰C (day)
The good book will tell you that Capsicum needs about 18 weeks of above 20⁰C for it to grow and the fruit to ripen, however this City fails miserably in this regard unless you happen to have a heated greenhouse. The attached graph will show you typically how the long term mean temperature graph looks in my location of Cheltenham.
Because of our climatic conditions we tend to get misshapen, multi-loculed, side lobe and misshapen fruit development at 12-15⁰C. For good flower development they need temperatures in the order of 16⁰C – 21⁰C however they fail to pollinate successfully at temperatures above 35⁰C which is common in Victoria in summer. The root temperature of 25 – 30⁰C benefits the growth regime considerably, so correctly coloured pots may be beneficial.
In the first option I start the growing season with seedlings that are normally available around August and growth would be stunted and flower development poor till October/November where night temperatures are still battling below 15⁰C and it may well be said that nothing happens till year end. The next year you have about 4 months before both the night and day temperatures drop below good growing conditions again.
I find that by growing your plants in this manner you establish good root stock and good vegetative growth and then over winter the plants and allow them to develop new growth in spring by cutting back the well-established woody stems to about 200mm long (photo 1a &1b showing two varieties), protecting the cuts from infection (I use tar paint) and allowing them to shoot early. The woody stock is less likely to develop botrytis attack which is common on green stems in winter in unheated greenhouses
Of course this means growing double the capsicum plants you need and pruning back 50% of them with the rest removed to start with new seedlings the following season.
The second option for capsicum to be started in Jan-Feb and to develop a sturdy plant before the onset of winter then starting with a good rootstock you will find the Plant will develop faster. I have used this method for many years growing Serrano chillies outside and it take 2 years to get a good high yield of fruit from the plants.
Photo 1 (a) – 30th May 2013 Photo 1(b) – 30th May 2013
Photo 2, SERANO CHILLIES 2nd YEAR GROWTH – 15/11/2013
If we study Photos 3a & 3b they are the capsicum plants provided by the association in July with fruit already well-established as they came out of a heated greenhouse however when they were planted out into a unheated greenhouse the growing tips were lost quickly and were not re-established until late in November. On the other hand the previous year’s plant photo 4 is developing well except for the poor fruit shapes.
Photos 3 (a) & 3 (b) Are Plants Provided by the Association
There are no simple solutions to this cold problem however a reasonable crop can be still obtained late in the growing season by careful management of the planting and pruning times and giving the cultivars the best spot in the greenhouse.