Chilly cherimoya

I AM ATTEMPTING to Grow A CHERIMOYA (Annona cherimola) INDOORS IN GORE’S CHILLY CLIMATE. THE LONG-TERM PLAN Is to HAVE It ESTABLISHED IN A GLASSHOUSE. THE NEW LEAVES COME THROUGH with vigour But EVENTUALLY BROWN At THE EDGES AND FALL Off. THE PLANT LOOKS very sparse DESPITE REGULAR water, SUNSHINE AND OCCASIONAL FERTILISER. ANY thoughts ON what COULD BE GOING ON? S Lee, Gore

You clearly like a challenge. Cherimoya, also known as custard apple because of its delicious flavour, is native to warm temperate valleys in ecuador and Peru so can be grown outdoors here in warm parts of the country in much the same way as avocados. The important factors when it comes to healthy growth are light, temperature above ground and in the soil, and water in the soil and as humidity in the air around the plant. Like avocados and some other subtropicals, cherimoyas are susceptible to root rot, which could cause leaf symptoms like those in your photo.

Here are some ideas to consider and things you could do in your quest to grow cherimoya in a pot in the deep south.

Light

Give your plant as much direct sunlight as possible. High light encourages photosynthesis and strong leaf and root growth.

Temperature

Protect it from extreme cold. You could provide heat from below to keep the roots warm by investing in a heating pad. They’re tiny electric blankets for plants, usually marketed as seed-raising or propagation pads, and are easy to use. Check them out online.

Water

Regardless of the time of year, allow the potting mix to dry out a little before watering and never have water sitting in the saucer as this encourages root rot. Cherimoyas are briefly deciduous towards the end of winter, often losing many leaves. In Gore, where winter days are shorter and winter light levels relatively low, your plant may lose all its leaves. With only a few leaves, it will need little water; if no leaves, then even less until new growth appears in spring.

Root rot control

There are a couple of products available from garden centres you could think about using. egmont Plantmate contains the beneficial fungus trichoderma, which in ideal conditions colonises the potting mix and helps reduce growth of root rot fungi.

You can add the granules by poking holes in the mix and pouring them in, or mix in with the potting mix when repotting. Kiwicare Buxus Blight Buster (thiram) is a fungicide you would water into the pot. But you can’t use them both – thiram will kill the beneficial trichoderma. (Two other products that i used to recommend for root rot control, Aliette and phosphorous acid, now seem to be no longer available to home gardeners.) remember to always follow product label recommendations.

Humidity

Some plants can suffer damage due to lack of moisture in the surrounding air. When we light the fire or switch on the heater, air conditioner or dehumidifier, the air can dry out so much that some tender leaves, like those on your cherimoya, can be damaged. So be careful where your plant is situated in the house – keep it away from air-drying heat sources.

Fertiliser

Only fertilise when the plant is actively growing leaves and don’t overdo it. Too much fertiliser in the mix can be an additional problem for plants prone to root rot.

Good luck!