Ask the Plant Doctor! How to deal with waterlogged gardens

Practise container gardening where you grow plants in containers rather than on the ground. Photos:123rf.com

Do you have a question about plants or how to maintain your garden? Send your questions to the Plant Doctor! Email your questions to [e-mail] with "Plant Doctor" in the subject field. Questions may be edited for brevity and clarity.

Q1: I have a mature curry leaf tree planted in a large pot and it’s growing well. But when I soaked them in water prior to cooking, I noticed that they become oily and sticky to the touch. I have not seen any aphids, ants, or any other bugs on the leaves or branches. I spray organic neem oil twice weekly and trim the plant frequently. – GJR

Curry leaves contain aromatic essential oils that give them their characteristic flavour and fragrance.

When soaked in water, some of these oils can leach into water. However, the amount of oil released depends on several factors: the freshness of the leaves, duration of soaking, and temperature of the water.

Fresher leaves and warmer water will result in more oil being released; however, water is a poor solvent for these oils and will not become oily.

Instead, it is more common for water to mildly take on the fragrance and flavour of curry leaves. Leaves must be heated or crushed to release these aromatic oils. So, while soaking the curry leaves in water may cause some oils to leach into the water, much of that oil will remain in the leaves.

Older, mature curry leaf trees may also produce more essential oils in their leaves. This is a natural process that does not necessarily indicate a problem.

However, trees subjected to environmental stresses such as insufficient watering or heat stress may also produce more essential oils.

If your tree is healthy, I would not worry about the “oily water”.

Curry leaves contain aromatic essential oils that give them their characteristic flavour and fragrance.

Q2: Certain parts of my garden are waterlogged, which leads to root rot. In addition to ensuring proper drainage, are there other ways to prevent root rot? I usually use Google for my garden problems. I am aware of various environments, and I have tried methods best suited for my location. It has always been a trial and error for me. Any advice?

Gardens that are prone to waterlogging can be difficult and expensive to rectify because their solutions will also have to consider the aesthetics of the garden. Where open drains are typically built to collect and channel excess water out of a farm or field, these drains may be unsightly for a garden.

There are several reasons for garden waterlogging. The topography of the garden may be such that water is channelled into the low-lying parts of the garden, causing water to accumulate in these parts.

Soils that are too clay-ey are also problematic because they have poor drainage. Shallow soils overlying a compacted soil layer or bedrock share the same poor drainage issues.

So, what do you do? If you have a large garden or place garden aesthetics as important, you may need to consult a drainage or garden expert to determine the cause of waterlogging and to receive a solution.

French drains may be implemented as a solution because they are built underground and are not visible above the soil. If the garden soil is on top of a hard, compacted soil layer, the layer may need to be broken.

Another solution is to plant on raised beds so that the plant roots are raised above the soil surface and not sitting in water.

Alternatively, container gardening can be practised, where plants, typically edible plants, are planted in containers such as pots, planter bins, or trays instead of in the ground.

Be extra mindful about watering to avoid overwatering your plants and clear the soil surface of any mulches or plant debris. Applying mulches or plant debris to the soil surface is typically beneficial in gardening, as it helps reduce moisture loss.

However, in waterlogged soils, their use can exacerbate this problem by retaining more water in the soil.

Some plants that are hardy in wet soils include taro (Colocasia esculenta), Umbrella Palm (Cyperus alternifolius), Bog Lily (Crinum americanum), and kangkung (Ipomea reptans).

Dr Christopher Teh heads the Dept of Land Management, Faculty of Agriculture, Universiti Putra Malaysia and coordinates the Healthy Garden series. The views expressed are entirely his own.