Please help me save my dying plant!
Hi Extension experts: I recently repotted this unknown species of plant in my office from a very small container with no drainage into a much larger container with a lot of drainage. The soil used was generic potting soil. Unfortunately, Spike is not doing well now. The leaf tips are turning brown and crunchy. Any thoughts on what the issue might be? I'm planning to take it home where there's better light, but I'm not sure what else it needs. Any advice would be greatly appreciated! Spike looked so healthy before I replanted it. Amy Phillips Bursch
District of Columbia County District of Columbia
This appears to be a form of Dracaena, a common houseplant grown for its colorful foliage; it could be a form of Dracaena fragrans or a similar species (their care is the same). Varieties differ in having different leaf colors and patterns of striping.
Moving it into a container with drainage was a good choice, as this will help prevent root rot due to overly-wet conditions. It's best to not give potted houseplants too large of a jump up in pot size as their roots don't fill the pot quickly enough to make use of the extra water that new soil will hold, which runs the risk of the roots staying too wet. Stepping it up gradually - say, from a 4" pot to a 5", or an 8" to a 10" - is best, and many tropicals do best when grown a bit "cramped" in their pots. That said, freshening the soil every year or so is important so that mineral salts (not just sodium) from tap water and fertilizers don't build up to damaging levels. Minerals are left behind as the water evaporates (and the plant only uses so much of those nutrients) and so increases over time to a point where they can damage roots. Similarly, water that's been put through a water softener (or even some bottled drinking waters) should be avoided as they contain sodium, which can reach toxic levels. Do not use fertilizer in winter, as the plant is growing much more slowly and will not need the nutrient supplementation.
Dracaena prefers indirect sunlight indoors, meaning a window receiving sunlight part of the day or a window receiving more sun but with a light sheer curtain pulled across it will give the plant an ideal amount of light. If growing it under artificial lighting, the best distance from the lights will be determined by what kind of lighting it is; office fluorescent lighting is pretty far from the leaves and is relatively dim for the plants' preferences. Given their tolerance for lower light for a time, though, is why they make popular office plants.
You don't mention how long its been since repotting and how long it took for these symptoms to develop, but it could be related to the onset of winter if your home or office has forced-air heating. Such heat is very low in humidity, which is something many houseplants will struggle with as they are native to habitats that are much more humid. Tips of leaves can dry out first in this case, especially if the plant's roots are either suffering from dieback due to over- or under-watering.
Does the office turn the heat down over the weekends or overnight, or is the plant in a drafty area? If so, since outside temps have been getting colder, it's possible the indoor temperatures have been getting too cold; Dracaena prefers to be at least 65 degrees F or warmer. Similarly, if it's in the path of the warm air from the heat, then it may be getting desiccated from that.
If the plant's near a window or table, did someone do some cleaning recently that may have hit the plant with over-spray? That might have caused the leaf damage (not on the tips, though).
Dracaena can contract to foliar bacterial infections; if in the crown (central growth point, where the leaves are emerging), then it will need to be trimmed out. Disinfect your cutting tools afterwards to avoid spreading it to healthy tissue. Some of the spotting of dying brown tissue in the center of the leaf (especially those younger leaves) could be this bacterial infection, as it looks similar to abiotic (environmental) causes.
Check the back of the leaves with the lighter yellowish spotting (in the photo taken from the side...the lowest leaf shows some of this). If you see circular ~2mm flecks of white or gray-brown, there might be scale on the plant as well. Scale is a sap-sucking insect that can cause discoloration where they feed. They are visible to the naked eye, so if you don't see them, that's probably not the cause of the spotting.
For general good health, water thoroughly when dry (so the water drains freely out the bottom holes) and wait until the soil dries some between waterings. In spring and summer, watering can be done a bit more frequently to keep the soil a bit more evenly moist. Give the plant as much humidity as practical, with an evenly warm temperature, and moderate light.