Spider Plant Babies: Why a Plant Makes Them, and Why Yours Has Not

Three weeks. That is how long a spider plant needs its nights to be longer than its days before it starts the stems that carry the babies, and it is the one thing about spider plant babies that no care guide leads with. The rest of this page follows from it: the plantlets (spiderettes, pups, whatever the shop called them) are a response to the calendar, and a plant that has never made one is usually not unwell.

The short version

1. Short days start it. The runners that carry the babies form after weeks of long, uninterrupted nights.
2. A lit room counts against that. An evening lamp is an interrupted night, in my reading of what the sources say.
3. Fertilizer works against babies. Two extension services say so in nearly the same words.
4. A snug pot helps. Spider plants make plantlets best when slightly pot-bound.
5. Cutting them is optional. Leaving them on is a legitimate outcome, not neglect.

What a spider plant baby actually is

A baby is the end of a sequence, and the sequence starts with a stem. Wisconsin Horticulture describes the trigger: Long, wiry stems up to 2 feet long are produced, sometimes with a few small leaves, typically in response to short days and long, uninterrupted nights for at least three weeks, although when grown indoors they may appear at any time of year. Flowers come at the ends of those stems, small and white, and then the part everyone is waiting for: After flowering, more leaves are produced at the end of the stems, forming small plantlets.

So the order is runner, flower, plantlet. Nothing about it is a sign of stress or of the plant being crowded, and nothing about it can be forced with water or food. The plant makes a stem when its nights have been long enough, and a baby when the flower on that stem is finished.

Why is my spider plant not producing babies?

Because one of three things is true, and none of them is illness. The plant has not had a long enough run of long nights, it is being fed too well, or its pot is too roomy. An apartment tends to supply all three without anyone deciding to.

The day-length rule is the one that decides most cases. NC State puts a number on it: Stolons and plantlets are light dependent and develop when the mother plant receives short days and long, uninterrupted nights, which it defines as less than 12 hours of light a day, held for at least three weeks. Wisconsin's wording is the same mechanism, and both say uninterrupted.

My reading of that word, for a plant that lives in a living room: the lamp counts. A plant on a sill in a room where the lights are on until eleven is getting a day that ends at eleven, whatever the sun did. That is my inference from the sources' phrasing rather than something either of them spells out, and it fits what I have seen, which is that the spider plants that never make babies are the ones in the rooms people actually sit in.

Fertilizer is the second cause, and it is the one good intentions produce. Wisconsin is direct: Heavily fertilized plants, however, may not form as many plantlets and excessive fertilizer may lead to tip browning. NC State says the same in fewer words: Do not over-fertilize, as this decreases plantlet formation. A spider plant that gets fed every time someone reads that it "should be fed during the growing season" is being steered away from the thing its owner wants from it.

The pot is the third. Plants grow and produce plantlets best when slightly pot bound, Wisconsin says, which is the opposite of the instinct to give a plant that seems unhappy a bigger home. Repotting a spider plant into something generous does two things at once: it removes the snugness that helps, and it gives the roots a season of new soil to fill before they think about anything else.

Read the three together and the plant that has never made a baby is usually a well-fed plant in a roomy pot in a room with the lights on. Nothing is wrong with it. It has simply never been given the conditions.

The calendar does most of it

After the September equinox the nights are longer than the days on their own, and they keep getting longer until December. A spider plant that gets to experience that, without a lamp extending its evenings, has the three weeks it needs before October is out. Clemson puts the season on it: Spider plants produce most of their offshoots when the days shorten in the fall.

The week-by-week shape of that decline, and why late September is where most of it happens, is in houseplant winter care; the figures there are for the sun, and the spider plant is reading the same thing.

What the plant cannot do is tell the difference between the sun and the ceiling light. If the room is lit until late, the day it experiences is the lit one, and the nights never get long. The move, if you want babies, is a room that goes dark when it gets dark: a bedroom, a hallway, the kitchen after dinner. It still needs its medium light by day. It needs the night to be a night.

When to cut spider plant babies

You do not have to cut them at all. Clemson gives both outcomes as equally fine: The plantlets can be detached to produce new plants or left on to create a very full basket. A spider plant trailing a dozen plantlets is the plant doing what it does, not a plant asking to be tidied.

If you do want new plants, the sources agree on the moment: when the plantlet has roots of its own. Clemson's instruction is to Detach them once roots have formed and pot directly into moist growing mix. A plantlet cut before it has any roots can still be rooted, but you are then asking a small plant to make roots on its own resources instead of its mother's, and Wisconsin's method, below, avoids that by not cutting first.

How to propagate spider plant babies

The method the extension services describe keeps the baby attached until it can stand alone. Wisconsin: Set the plantlet, still attached to the mother plant, on the surface of a pot filled with soilless potting medium and allow it to root before severing the stem connecting it to the mother plant. The one practical difficulty is holding the plantlet down, and the same page has the answer: A bent paper clip or piece of wire can be used to hold the plantlet in contact with the soil until it develops roots.

So: a small pot of potting mix beside the mother, the plantlet pinned to its surface with a paper clip, the runner left intact. Water the small pot when its surface dries. When the plantlet resists a gentle tug, it has roots, and the runner can be cut. Nothing about this needs a windowsill jar, and the reason the jar is the weaker method for most plants is worked through in how to propagate houseplants.

For a plantlet that has already grown roots while dangling in the air, which they often do, skip the pinning: cut it free and pot it into moist mix, as Clemson describes. Either way the new plant goes into soil, and a snug pot rather than a generous one, for the reason in the section above.

Light, water, and the cat

A spider plant is easy in the ways that matter in a rented room. NC State places it in the middle of the light scale: Spider plant prefers medium light levels yet can tolerate deep shade, with one firm limit, It is intolerant of direct sunlight. Clemson allows a little more: They can tolerate some direct sunlight, but midday light may scorch leaves. Medium light, a few feet from a window, no midday sun on the leaves.

On water, Allow the soil to dry slightly between thorough waterings, and Reduce watering during winter. The plant is built for gaps: Thick, fleshy roots and rhizomes evolved to store water, allowing spider plants to survive inconsistent watering, which is why a forgotten spider plant tends to be fine and a fussed-over one tends to rot. Brown leaf tips are a separate subject with a separate page, brown tips on houseplant leaves, and fluoride in tap water is one of the things it covers.

And the cat: spider plant is on the ASPCA's non-toxic list for cats and dogs, one of only three of the common houseplants on this site's toxicity table that are. It is the plant to put where a pet can reach, and the plantlets are the part a cat is most likely to bat at.

Common questions

Why is my spider plant not producing babies? Most often because it has not had at least three weeks of nights longer than its days, which NC State defines as less than 12 hours of light a day. A room that is lit in the evening extends the plant's day past sunset. Two other causes are heavy fertilizing, which both Wisconsin and NC State say reduces plantlet formation, and a roomy pot, since spider plants produce plantlets best when slightly pot-bound. None of the three is a sign of poor health.

When to cut spider plant babies? When they have roots of their own, and only if you want more plants; leaving them on is fine.

Spider plant babies in water or soil? Soil. The extension methods root the plantlet in potting mix, either while it is still attached to the mother or after it has grown roots in the air. Water rooting works often enough to be popular, but roots grown in water are built for water, and the plant stalls when it is moved to soil. That argument is made in full in how to propagate houseplants.

Do spider plant babies need roots before cutting? They do not need them, but the cut goes better if they have them. Clemson says to detach once roots have formed. If yours has none, use Wisconsin's method: pin it to a pot of mix while it is still attached, and cut the runner once it has rooted.

How long do spider plant babies take to root? No extension service publishes a day count, and the honest answer is to tug gently and see. A plantlet that resists has roots.

One thing to do this month

Count the hours the lights are on in that room after dark.

If the answer is three or four every evening, the spider plant on the sill is living in a summer that never ends, and no amount of care will get a stem out of it. Somewhere the lights go off at dusk is where the babies come from, and it costs nothing to move the pot there in September and look again in November. A spider plant is also one of the plants you can keep in The Windowsill, the game on this site, though its babies are the one thing about it the game does not model yet.