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Monday, December 11, 2017

How To Grow Rosemary in the Tropics

1 tiny seedling in a BIG pot in July 2017.

The same seedling in December 2017.

7 tiny seedlings in generous pots in July 2017.

The same seedlings in December 2017.

Soil Mix
50% perlite + 50% Jiffy potting mix. However, any off the shelf cactus mix will work.

Sun Conditions
As much sun as possible. In the summer, near Aix en Provence, rosemary gets 10 to 11 hours of direct sun in temperatures of 40 Deg Celsius. They LOVE the sun. The more sun you give them, the faster they grow.

Water Conditions
They hate wet feet. Never water at night. Always water the rosemary at the time when the sun shines directly on its leaves. This ensures immediate transpiration throughout the plant and prevents wet feet at night.

Rosemary roots are susceptible to root rot. Once the fine tendrils of roots begin to rot, the rosemary will be unable to uptake water and nutrients. The leaves will begin to curl. The bottom leaves will turn brown.

If you do nothing, the root rot will spread and your rosemary will die.

How To Rescue a Rosemary Plant from Root Rot
Uproot the plant. Trim off the rotted roots. Be THOROUGH when you trim, or the root rot will spread. Then, your plant will die. Remove as much soil as possible. Lay the plant on DRY newspaper to dry out. When nice and dry, repot into CACTUS mix. 

Remember to note the percentage of roots you have removed. You will later need to trim the same percentage off the leaves and stems too.

Placement of Rosemary
Place under glass roof to get direct sunlight but NO RAIN. Rosemary hates rain. It hates daily watering. I only water when I feel the pot is very light (i.e., soil is fully dry). Feel the weight of your pot before watering. Feel the weight of your pot after watering. Water only when soil is DRY.

When watering, water generously until water drains out the pot holes below.

How to Rescue a Root Bound Rosemary
Most people prune the leaves of the rosemary to eat. However, to ensure the long term survival of a potted rosemary, it is important to trim its roots too. When the rosemary's large roots fill the pot, there is no space for the fine roots to grow. When that happens, there is again insufficient uptake of water and nutrients. The bottom leaves will turn brown and wither away.

A potted rosemary plant needs to be pruned at the roots and repotted in new cactus soil at least once a year. A video speaks a thousand words. Click HERE.

How to Fertilise a Rosemary
I give worm pee, Guanito pellets, Phenix pellets, gypsum powder, home made kitchen compost and worm poo. These are all organic fertilisers. I mix everything in water and steep overnight. Then, I water to all my plants, rosemary included.

I water all my plants with this very dilute fertiliser solution. It is always better to give very diluted fertiliser water, than to give a lot of fertiliser pellets. Too much fertiliser pellets will lead to fertiliser burn.

Rosemary From Nurseries or Cold Storage
It is in the financial interests of rosemary growers to...
- get a full and lush pot of rosemary in as little time as possible
- NOT facilitate the long term survival of your rosemary plant.

Hence, growers will crowd 4 to 5 seedlings to a pot. The rosemary hates having its roots crowded. If you want your rosemary to grow big, you need to give the roots ample space to grow, failing which, your rosemary will become root bound and die.

Hence, when you get a pot from the nursery, tease apart every individual plant and repot in its own generous pot with ample space to grow. Then, ensure a lot of direct sun, very little water and very well draining soil.


Anonymous said...

Hi, Are those grown in Singapore?!
Also, how often do u fertalise your rosemary plants? Thanks!

Petunia Lee said...

Yes... these are in Singapore. I fertilise about once a month.

Irene Soh said...

Dear Petunia, Interesting read! With new determination, I shall try to grow them again :)
Thank you :)