Gadenin日本語Get the appWork out which kind of problem it is
Spider plants get very little genuine disease. Nearly everything that goes wrong is either the water and the feeding, the position, or a small number of sap sucking pests. Sorting the symptom into one of those three before you act saves you treating a watering fault with an insecticide.
Start by touching the compost and turning a few leaves over. The compost tells you whether roots are involved; the undersides tell you whether anything is living on the plant. Almost every diagnosis on this page comes from those two checks.
| Symptom | Most likely cause | Where to look next |
|---|---|---|
| Dry brown points on most leaves | Fluoride, salts or dry air | Brown tips section |
| Fine pale speckling, faint webbing | Spider mites | Pests section |
| Sticky leaves, white fluff in the crown | Mealybugs or scale | Pests section |
| Soft yellow leaves collapsing at the base | Root rot from wet compost | Rot section |
Brown tips: the commonest complaint of all
A brown, dry, hard point on the end of otherwise green leaves is the classic spider plant symptom and it is almost never a disease. Salts concentrate at the tip as water evaporates from the leaf, and the tissue there dies. The plant is sensitive to fluoride and chlorine in tap water in particular, at concentrations that other houseplants ignore entirely.
The damage is permanent on a leaf that already has it, so you judge whether your fix worked by watching the leaves that open afterwards. Give it two months before deciding.
- Change what you water with Use rainwater or filtered water if you can. Failing that, stand tap water in an open jug overnight, which lets chlorine off, though it does nothing for fluoride.
- Flush the pot twice a year Run water through the pot for two or three minutes at a sink until roughly four times the pot volume has passed through, and let it all drain away. This carries out accumulated fertilizer salts.
- Feed less than you think Half strength liquid feed once a month in the growing season is plenty. Overfeeding is the second biggest cause of tip burn after tap water.
- Raise the humidity a little Group plants together, stand the pot on a tray of damp gravel, and keep it out of the direct blast of a radiator or air conditioning. Winter heating is when tips brown fastest.
Trim the brown off with sharp scissors, cutting to a point that follows the natural taper of the leaf. Leave a hair's width of brown rather than cutting into green tissue, which simply browns again.
The pests worth knowing
All of these suck sap and all of them are far easier to deal with early. Check the leaf undersides and the crown once a fortnight, and quarantine any new plant for two weeks before it joins the others.
| Pest | How to recognize it | What to do |
|---|---|---|
| Spider mites | Fine pale stippling, webbing in the leaf axils, worst in dry heat | Rinse the undersides, raise humidity, treat with soap or oil weekly |
| Mealybugs | White cottony lumps in the crown and leaf bases | Dab each one with alcohol on a cotton bud, repeat weekly |
| Scale | Small brown limpet like bumps, sticky leaves below | Scrape off by hand, then treat with horticultural oil |
| Aphids | Clusters on flower stems and new plantlets | Wash off with water, repeat every few days |
| Fungus gnats | Small flies rising from the compost when disturbed | Let the top inch dry hard, empty the saucer |
Sticky leaves are honeydew, excreted by mealybugs, scale or aphids. If leaves are sticky and you cannot find the insect, look at the plant on the shelf above as well.
Root rot and crown rot
The thick storage roots hold their own water, so a spider plant is much more often killed by too much water than too little. Rot shows as leaves yellowing and softening from the center of the plant outwards, a sour smell from the compost, and a plant that stays limp however much you water it.
Crown rot is the same problem in a different place: it comes from planting too deep or from water sitting in the center of the plant, and it turns the base of the leaves brown and mushy. Both are recoverable if you catch them while some firm white root remains.
- Take it out and look Slide the plant from the pot and inspect the roots. Firm and white or pale tan is healthy. Brown, soft, hollow or smelling means rot, and you need to act rather than adjust the watering.
- Cut back to clean tissue Wash the compost off and cut away every soft root with clean scissors. Remove any leaf whose base has gone soft, taking it right off at the crown.
- Repot small and dry Pot into fresh free draining compost in a pot only just large enough for what roots remain, set the crown level with the surface, and water sparingly until new leaves appear.
- Save plantlets as insurance If the parent is badly gone, root any healthy plantlets straight away. It is often the fastest route back to the plant you had.
Cultural faults that look like disease
Several complaints that get treated as pests or infections are simply the plant responding to where it is standing. Check these before reaching for anything in a bottle.
| What you see | What is actually happening | The fix |
|---|---|---|
| Pale bleached patches after a move | Sun scorch through glass | Move back from the window or filter the light |
| Blackened marks on leaves in winter | Leaves touching cold window glass | Move the plant into the room overnight |
| Stripes fading to plain green | Not enough light | Move one step closer to a window |
| Floppy soft growth, no plantlets | Too much nitrogen and too little light | Stop feeding, move brighter |
| Chewed and torn leaf ends | A cat has been at it | Hang it out of reach, offer cat grass instead |
Write down the date a problem first appeared, where the plant was standing, and what you changed. Most of these faults are seasonal, and one year of notes tells you which month to expect them next time.