Rubber Plant leaves with brown spots
Hi! I so want to be a green thumb but keep bumping into barriers... I bought this rubber plant about 8 weeks ago. When we purchased it a few leaves had some brown spots on the edges but I ignored it. Now, apart from the new growth at the top, EVERY leaf has brown spots/edges - it doesn't look that nice. When first brought home, the top of the soil seemed to get dry pretty quickly so it was probably well watered twice a week, but in the last few weeks have just been watering once/wk if that, because I'm wondering if over-watering was the culprit. It sits in the same plastic pot it came in with the tray underneath. I think we gave it some seasol once, when we first got it. It gets very good general sunlight in the room, and direct light maybe 1 hr a day, and the leaves are no different on the side that faces more away from the sun. Please help my rubber plant look fresh again!
Certified GKH Gardening Expert
Brown spots on the leaf margins (edges) are most commonly due to water deficit/drought stress. When a plant isn't getting enough water, the tips and edges are the farthest from the source so they go dry and brown first. Over watering or fungal infection would usually take more time to show signs and would present differently. If the soil surface dries fast, the pot may have a very porous soil that drains fast and doesn't retain soil moisture.
Leaf margin drying can also be due to fertilizer burn. It isn't a thermal burn but a dessication, drying of the leaves, leaf tips and margins first, due to high salts in chemical fertilizers. Seasol liquid seaweed fertilizer shouldn't do that, but if you also used a high nitrogen fertilizer that could be a contributing factor.
Check the soil moisture content, with a finger or a soil moisture meter. If you find that the soil is draining too fast and once or twice a week watering is not enough, then you may need to re-pot the plant with a better potting soil. Rubber plants need consistently moist soil but not soggy.