Growing Herbs in the Tropics
Answered by: Conrad Richter
Question from: Glenn Schwendinger
Posted on: October 28, 1998

We recently purchased a variety of seeds and brought them to Belize Central America. We are starting a Thai/French Restaurant and are attempting to grow our own herbs for this application. We have planted the first series with limited success. I wonder if you have any experts that can give us some tips for growing in this climate which is predominately hot & sunny with strong ocean breezes.

There is no doubt that the tropics present serious challenges for herb growers. Some of the reasons are:

1. Heat. Many of the common culinary herbs are native to temperate regions and do not tolerate heat very well. Good examples are tarragon and chives. These need a cool period once a year, otherwise they languish and become susceptible to diseases. We notice that tarragon plants that are overwintered in our greenhouses do not perk up in spring like plants that were allowed to freeze for a month or two outdoors.

2. Heavy rain. Many herbs do not tolerate "wet feet" for long periods. In the tropics it is common to have rainy seasons when the soil becomes waterlogged. This is fatal for herbs such as rosemary, sage and thyme.

3. Humidity. Even when during the drier seasons the humidity can be heavy causing fungus diseases to multiply on leaves and other parts of the plants. Sage, lavender and rosemary are known to suffer from this problem.

4. Poor soil. In the tropics soils often have little organic matter and nutrients. Amendments such as rotted manure and compost are essential.

5. Pests. The diversity of insects and other pests in the tropics is vast. We have heard that ants and termites can be serious problems, defoliating seedlings and young transplants before they can get established.

What to do?

Whatever you do, do not give up! It is certainly possible to grow herbs in the tropics, but it will take some experimenting to find out what will grow in your situation. Here are some possible solutions (the numbers correspond with the problems listed above):

1. Choose heat tolerant varieties. Acceptible substitutes exist for many of the common herbs. For example, the sweet marigold, also known as mexican tarragon, is a very good substitute for french tarragon. Welsh onion grown as an annual can substitute for chives.

2. Plant in raised or sloped beds. Raising the beds or planting on slopes helps to move excess rain away from the roots. Adding sand or fine gravel will help to improve soil drainage. When the rains are heavy, clear plastic row covers will help keep the rain off the plants (but make sure that the sides are open to allow ventilation).

3. Humidity is difficult to control, but planting in areas exposed to the wind will help. Also, avoid herbs with hairy or woolly foliage, as these tend to collect moisture from the air.

4. Fertilize. Organic fertilizers such as well-rotted manure and compost are essential for building up the fertility of the soil. Establish a composting scheme for the kitchen waste.

5. Avoid direct sowing where possible. Start seeds in flats or pots that are elevated from the ground to minimize exposure to leafcutting ants and other foraging pests. Once the plants are well established in pots, they stand a better chance to survive. Investigate barriers and traps; for instance, you can protect plants with a barrier of water around them. But even your best efforts may fail with some tender herbs and these varieties should be replaced with other, tougher varieties. It pays to observe what varieties are grown in your area because often the locals have learned long ago what works and what doesn’t.

We have also notice that many items are for shipment to Canada only, can you explain.

Some items require special permission to import into other countries. In the case of bulbs and tubers, especially, most countries impose restrictions that require expensive laboratory tests. In these cases, unless you are interested in ordering very large amounts, we cannot justify the extra expenses involved.

Plants of particular interest to us are those associated with Thai food as well as berries & hardy large flowers suitable for full sun tropical climate.

We carry many Thai and Vietnamese herbs. Look for herbs such as thai basil, vietnamese balm, mexican coriander, rau om, lemongrass, water spinach, thai pepper, and more.

We do not carry berries. Of the flowering herbs, try nasturtium, kenikir, hyacinth bean, passion flower and hollyhock.

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