Plant Doctor Archive

Growing mangoes

I HAVE a few problems growing mango by seed in Auckland. I know it's too cold outside, but I would like to grow one inside. Usually I dry the seed for 2 or 3 days, then put it in sand or pumice mix on top of good potting mix. I keep it damp around the seed and quite often, within 2 weeks, a plant will develop. I keep the pots on a heating pad so they are not too cold. Most plants seem to grow OK till about 2 to 3 months and then the leaves go brown and eventually drop off. The plant then slowly deteriorates and dies. I have had mono and polyembryonic seeds - on the latter sometimes the first plant dies then second one develops and dies after a few weeks. Also, sometimes the seeds go mouldy before anything develops. Lately I have tried copper spray on some plants and I will have to see if it works.

FIRSTLY, it sounds as if your mango seeds are becoming infected with fungal disease. It should be possible to grow them into plants as long as you control disease and keep them warm enough.

Thoroughly clean the seed of as much flesh as possible, even giving it a light scrub with a brush, then soak for 15-20 minutes in a solution of a general fungicide such as Bravo (or Thiram, if you can get it) or a sterilising solution of 1 part bleach (such as Janola) in 10 parts of water. Then leave the seed to dry for 2-3 days before sowing.

The second problem seems to be root rot affecting them once they start growing. Many tropical plants succumb readily to root disease so you'll need to be very careful to avoid overwatering them, particularly at cool times of the year or when there is poor light.

Make sure to use a very free-draining mix and don't ever have the bottom of the pot sitting in water. Allow the mix to dry out before watering again, but not so much so that the plant wilts, and then only give them a little water at a time.

You could also try adding the beneficial fungus Trichoderma to the potting mix (some have it added) or using the fungicide No Root Rot as a spray on a regular basis.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.