1. Choose Your First Cactus
Not all cacti are equal for beginners. Start with something forgiving:
| Species | Difficulty | Why It's Good | Growth Rate |
|---|---|---|---|
| San Pedro (T. pachanoi) | ★☆☆☆☆ | Fast grower, forgiving of mistakes, easy to root | 30-60cm/year |
| Golden Barrel (E. grusonii) | ★★☆☆☆ | Classic, tough, handles neglect well | 5-10cm/year |
| Bolivian Torch (T. bridgesii) | ★★☆☆☆ | Hardy, vigorous, beautiful blue-green color | 20-40cm/year |
| Paper Spine (T. articulatus) | ★★★☆☆ | Interesting segmented form, offsets easily | 10-20cm/year |
2. Soil — The Most Critical Factor
90% of cactus deaths are from the wrong soil. Regular potting soil holds too much water and causes rot. You need a mineral-heavy, fast-draining mix.
The Ideal Mix (80/20 Rule)
Component Reference
| Component | Drainage | Best For | Notes |
|---|---|---|---|
| Pumice | ★★★★★ | All-purpose | Gold standard. Porous, stable, doesn't break down. |
| Lava Rock | ★★★★★ | Trichocereus mix | Adds minerals and weight. |
| Perlite | ★★★★☆ | Seedlings, budget mix | Floats, breaks down. Cheap alternative to pumice. |
| Turface | ★★★★☆ | Gritty mix, bonsai | Calcined clay. Holds water without staying wet. |
| Coir | ★★☆☆☆ | Moisture retention | Eco-friendly peat alternative. |
| Worm Castings | ★★☆☆☆ | Nutrition | Use sparingly — 5-15% of total mix. |
3. Watering — Less Is More
The #1 killer of cacti is overwatering. Cacti store water in their stems — they're designed to go weeks without it.
When to Water
- Spring/Summer (Growing season): Water every 7-14 days. Let soil dry completely between waterings.
- Fall: Reduce to every 2-3 weeks as temperatures drop.
- Winter (Dormancy): Water once a month or not at all if kept cool (<10°C).
How to Water
Water thoroughly until it runs out the drainage holes. Don't just mist the surface — deep watering encourages deep roots. Then wait until the soil is bone dry before watering again.
4. Light — Sun Lovers
☀️ Full Sun Species
San Pedro, Bolivian Torch, Peruvian Torch, Golden Barrel, Turk's Head — need 6+ hours direct sun. Indoors: south-facing window or grow light.
🌤️ Part Shade Species
Peyote, Star Cactus, Aztekium, Haworthia — bright indirect light. Morning sun only. Too much direct sun causes yellowing (sunburn).
5. Potting
Pot Selection
- Terracotta/Clay: Best choice. Porous — lets soil dry faster. Prevents rot.
- Plastic: Retains moisture longer. Only use with very gritty mix.
- Ceramic (glazed): Traps moisture. Use only if you're experienced.
Always use a pot with drainage holes. Never pot a cactus in a container without drainage.
Pot Size
The pot should be just big enough to fit the root ball. Too-large pots hold excess moisture and cause rot. A good rule: the pot diameter should be ~2-3cm wider than the cactus.
6. Cactus Life Stages
7. Fertilizer
Cacti are light feeders but benefit from balanced nutrition during the growing season.
- NPK ratio: 10-5-5 or 15-5-5 at ¼ to ½ strength
- Schedule: Feed every 2-4 weeks from April to September. Stop completely October-February.
- Calcium is critical: Cacti need more calcium than most plants. Gypsum, Cal-Mag, or crushed oyster shell.
- Organic option: Diluted worm casting tea + kelp meal. Slow-release, gentle.
8. Common Pests & Problems
🕷️ Spider Mites
Fine webbing on new growth. Treat: neem oil spray, repeat weekly.
🐛 Mealybugs
White cottony clusters on spines. Treat: isopropyl alcohol on q-tip.
🟤 Scale
Brown waxy bumps on ribs. Treat: scrape off, apply neem oil.
⚠️ Root Rot
Mushy base, discoloration. Surgery: cut above rot, sulfur powder, re-root.
☀️ Sunburn
Yellow/brown patches. Move to part shade. Scar tissue is permanent.
🌳 Corking
Brown tough skin at base. Normal aging — not rot. Leave it alone.
9. Winter Dormancy
Most cacti need a cool, dry winter rest to bloom the following year.
- Temperature: 5-12°C indoors. Hardy species (T. terscheckii) down to -8°C.
- Water: Once a month, or not at all if kept very cool.
- Light: Keep bright but reduce hours.
- Fertilizer: None. Feeding during dormancy causes etiolation (thin, pale growth).
Winter Dormancy by Species
| Species | Dormancy Style | Min Temp | Water | Light | Notes |
|---|---|---|---|---|---|
| San Pedro (T. pachanoi) | Cool & dry | -5°C | Every 3-4 weeks | Bright | Can handle occasional light frost if dry. Stops growing below 10°C. |
| Bolivian Torch (T. bridgesii) | Cool & dry | -3°C | Every 3-4 weeks | Bright | Hardy. Continue minimal watering. |
| Argentine Saguaro (T. terscheckii) | Cold hardy | -8°C | Monthly | Bright | Most cold-hardy Trichocereus. Tolerates wet cold better than others. |
| Golden Barrel (E. grusonii) | Cool & dry | 0°C | Monthly | Bright | Needs protection from frost. Rot-prone if cold + wet. |
| Peyote (L. williamsii) | Bone dry | 5°C | None | Indirect | CRITICAL: zero water in winter. Shrivelling is normal. Watering = rot. |
| Paper Spine (T. articulatus) | Minimal | 2°C | Every 4-6 weeks | Bright | Shorter dormancy than other cacti. Native to milder Argentina. |
| Star Cactus (A. asterias) | Cool & dry | 3°C | Monthly light mist | Indirect | Can shrivel noticeably. Don't panic — it plumps back in spring. |
| Aztekium (A. ritteri) | Bone dry | 8°C | None | Indirect | Extremely rot-sensitive in winter. Keep warm and absolutely dry. |
| Living Rock (Ariocarpus) | Bone dry | 5°C | None | Bright | Winter-growing in habitat but needs dry cultivation in captivity. |
| Myrtillocactus | Minimal | 0°C | Every 2-3 weeks | Bright | Milder dormancy. Continues slow growth if kept warm. Keep above 5°C. |