The advice below applies to most cacti and those other succulents that adapt to growing in our summer. Some succulents do not fit this pattern as they grow and flower during the autumn and winter.
January/February: Very little activity is seen these months and most plants are best left dry to rest. Make sure your heating systems in the greenhouse are working correctly and maintaining the required temperature. A maximum/minimum thermometer is useful for this and will soon repay its cost by indicating when you can turn down the heating. Be watchful for drips from condensation and glass leaks as these can cause fatalities. Windowsill plants should be away from frosty glass. No watering is necessary.
March: The growing season begins with the first sign of buds and new growth. Bright weather will bring on this flurry of activity. Repot those plants which need it, using dry compost which has acclimatised to the greenhouse temperatures, but remember not to water for at least two weeks afterwards, more if there has been any root damage or rot has been found. Ventilate the glasshouse on warm days. Watering can begin once the weather improves, preferably on a bright morning. Buds will appear on Mammillaria, Rebutia and other early flowering plants. Seeds can be sown in a heated propagator (preferably thermostatically controlled).
April: Repotting continues in earnest. Ventilation is important from now on and right through the season. Seeds may be sown without the use of a propagator. A warm, bright windowsill is ideal. Some light shading may be needed against the midday sun.
May: Many plants are in flower this month. Water thoroughly with regular feeding. Be vigilant for pests. Give a first dose of insecticide, either systemic, contact or biologically by buying the predators of the pests found.
June: When the risk of frosts has completely gone, many plants, such as Agave (Fig.3), benefit from a spell outside. As the weather improves, provide more ventilation, especially at night. Continue watering and feeding regularly.
July/August: Continue to ventilate. It may be necessary to shade in very strong sunlight. Be careful, red spider mite is very active in hot dry conditions. Keep the greenhouse clean and tidy. Continue watering and feeding as before. Inspect your plants carefully and, if needed, apply another dose of insecticide in August.
September: A watchful eye on the weather is needed. If it turns wet and cold, stop watering. Otherwise water moderately with a high potash fertiliser to strengthen plants for the winter. Reduce watering towards the end of the month and give a last dose of insecticide if needed.
October: Check your heating systems for the winter. It helps to keep a fan circulating the air over winter to reduce the risk of botrytis (grey mould). Water only if the weather is warm and allow pots to dry out by the third week of month, or earlier if a dull, cold spell is forecast.
November/December: The return to the dormant stage is complete. Plants properly dried will survive lower temperatures. Some extra insulation will ensure lower fuel bills. No watering is necessary apart from winter growing succulents. The BCSS Seed List arrives with the December CactusWorld so start planning what to grow for the New Year!
NOTE Some growers repot during the winter, perhaps in February when the winter is nearly over, the days are lengthening and the time to start watering is only a few weeks away. However in this case, make sure that the compost mix is completely dry and leave the plants for at least three weeks before watering, more if there is any root damage or rot.
A full set of cultivation leaflets are given free to new members and are available for sale in our shop.