Cacti are often considered easy plants to grow.  So, why don't they always grow well?

The first rule of thumb is to avoid overwatering, which is one of the most common reasons why cacti become sick in moist and humid Singapore. When in doubt, avoid watering as cacti are adapted to tolerate periods of drought, so it is best to water when the growing media is dried out. To test if your cactus needs water, place a pencil in the soil all the way to the bottom. If moist soil clings to the pencil when you pull it out, it still has enough water.

When you do water, water thoroughly, but be sure to empty the saucer of excess water as extended waterlogged conditions will cause the roots and then the whole plant to turn mushy like a rotten fruit.

Second, use a well-draining mixture. This allows excess water to drain freely from the pot and allows the roots to breathe. A mixture of one-third potting soil, one-third sand and one-third gravel will work well on many types of cacti.

Choose a shallow pot that's not too big, and line the bottom of the pot with rocks before filling it with the mix. In nature, cacti are often found on soil with little nutrients, so they're not used to heavy meals. Feed your cacti lightly with a solution of low nitrogen fertiliser (like 5-10-10 NPK, which stands for 5% nitrogen, 10% phosphorous and 10% potash) diluted to half the dose recommended on the label, every two to three months, this helps the cactus to grow robustly.

Third, place your cactus in a bright and airy location. Depending on the type of cactus, it will appreciate bright indirect light to full sunlight. Try not to change its light condition suddenly if it is used to growing in a darker location, but help them to adjust gradually by placing it in indirect light for a while, and then moving to bright light. With these pointers in mind, you can grow beautiful, thriving cacti!

By Jennie Tang
Pictures of cacti from Flora and Fauna Web

The Sun Garden at the Singapore Botanic Gardens features a fascinating variety of cacti.

Caring for cactus is easy as long as you remember the three rules of maintenance: water the correct amount; use the right potting mixture; and give it sufficient light.