Gadenin日本語Get the appThe year in outline
Almost everything you do to a cactus happens in one half of the year, and the skill is in judging the two switch points: when to start watering in spring and when to stop in autumn. Get those right and the rest of the calendar looks after itself.
| Season | Watering | Feeding | Jobs |
|---|---|---|---|
| Early spring | One light watering to wake the roots | None | Repot, inspect roots, check for pests |
| Late spring | Full soak whenever dry two or three days | Start, monthly | Take offsets and cuttings, sow seed, harden off |
| Summer | Soak on the same cycle, evening in a heatwave | Monthly | Shade at midday under glass, keep air moving |
| Early autumn | Halve the frequency | Stop | Bring outdoor plants under cover, check for pests |
| Late autumn | Last watering, then none | None | Move to the cold bright room |
| Winter | None below 50F (10C) | None | Look at the plants weekly, do nothing else |
Spring: wake it up slowly
After months without water the plant is shrunken and the roots have partly died back. A full soak onto that root system is the classic way to lose a plant that survived the whole winter. Give it a quarter of a normal watering as the days lengthen and the room warms, then wait two or three weeks.
Watch for the sign that it has restarted: fresh, glossy growth at the crown, or new spines that are brighter and softer than the old ones. From that point, water normally and start feeding once a month with a dilute high-potash feed.
This is also the whole window for disruptive work. Repotting, dividing, taking cuttings and sowing seed all belong to late spring and early summer, when the plant has the season ahead of it to recover.
Buds appear in spring on plants that had a proper cold dry winter. Once buds are forming, do not move or turn the plant. A change of light direction at that stage is a common reason buds dry up and drop.
Summer: the growing season
This is when the plant does its year's growing, so it should be as bright and as airy as you can make it. A plant standing outdoors from late spring, once hardened off, puts on visibly harder and better colored growth than the same plant indoors.
Keep rain off it. A cactus outdoors in a wet week sits in saturated compost with no way to dry, and that combination undoes a whole season. Under an open-sided cover or the eaves of the house is ideal.
Above 95F (35C) many desert cacti pause and stop taking up water. Stretch the interval, shade the pot rather than the plant if it is in a small container, and water in the evening so the roots are not in hot wet compost through the afternoon.
Autumn: start the taper early
The autumn mistake is leaving the reduction too late. Compost that is still wet when the nights turn cold is the exact condition that rots the root plate, and the damage is invisible until spring.
Halve the watering frequency as soon as the nights cool, stop feeding entirely at the same time, and plan the last watering for roughly a month before the plant goes into its cold room, so it enters the winter with genuinely dry compost.
- Bring outdoor plants in before the first cold nights Move them under cover once nights start falling below about 50F (10C). Do it while the weather is still dry so the compost is not soaked when they come in.
- Inspect every plant on the way in Check the areoles, the crown and the underside of the pot rim for mealybugs and slugs before the plants stand together on a shelf all winter.
- Clear away dead flowers and debris Pull off spent flowers and any fallen leaves lodged between the ribs. Damp debris against the body over a still winter is a starting point for fungal spotting.
- Give the last watering on a bright morning Water once more while the weather is still warm enough to dry the pot through within a week or two, then stop completely.
Winter: the rest that makes flowers
Through the coldest months the plant should be bright, completely dry, and held between 41 and 50F (5 to 10C). This is not neglect and it is not merely tolerated: it is the condition that triggers flower buds. A cactus kept warm and watered all year will stay alive for decades and never bloom.
Expect the plant to shrink, wrinkle and pull its ribs in. That is what a resting cactus looks like and it reverses within a fortnight of the first spring watering. Do nothing about it.
Keep it away from freezing, away from a radiator, and out of a dark cupboard. Cold with light is a rest; cold with darkness is a slow decline, and warmth with poor light produces the thin stretched section you see at the top of so many neglected plants.
Look at the plants once a week through winter without touching them. You are checking for softening at the base and for mealybugs, which stay active in a cool room, and for nothing else.
What to write down each year
Four dates per plant carry almost all the useful information: the last watering before the rest, the coldest temperature reached in the winter room, the first watering of spring, and the date any bud was first visible.
After two or three seasons those records answer the question everyone eventually asks, which is why one plant flowers and the identical one beside it does not. It is nearly always a difference in how cold and how dry the winter was, and only a written record will show you that.
Add the repotting date and the pot size to the same note. A cactus gives so little outward sign of being potbound that the record is the only practical way to know when it was last moved.