March is the month I look forward to most in the houseplant calendar. The spring equinox arrives around March 20, day length crosses twelve hours, and within days of that crossing my monstera, pothos, and philodendrons are visibly moving again. The whole care routine shifts this month — more water, first fertilizer of the year, repotting season begins, and thrips show up with the new growth flushes.

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What's happening to your plants in March

The spring equinox (on or around March 19–21 in the Northern hemisphere) is a biological trigger for many houseplants. Equal day and night length, combined with the increasing sun angle of late March, produces the light intensity cues that signal plants to break dormancy and resume active growth.

By mid-March, I am typically seeing new growth on most of my tropical foliage plants. Pothos and heartleaf philodendron are usually first, extending new nodes and leaves. Monstera follows with its tightly rolled new leaf emerging from the center. Even plants that appeared completely static through January and February start showing visible change in March.

What this means physiologically, per NC State Extension: the plant's photosynthetic rate increases with higher light intensity, which increases its demand for water, carbon dioxide, and nutrients. Root activity increases. The plant begins actively building new cells. This is a fundamentally different metabolic state than the dormancy you managed through winter, and it requires fundamentally different care.

The shift doesn't happen overnight. In early March, many plants are still in the transition zone — more active than January but not yet at full spring pace. By late March, the transition is largely complete for most tropical foliage plants, and spring care practices apply.

Southern hemisphere readers: your March is equivalent to our September — the beginning of fall dormancy transition, time to taper watering and fertilizer, not increase them.

Light this month

March light improves meaningfully through the month. The sun angle is rising, day length is increasing by about two minutes per day, and in many Northern hemisphere regions the cloud cover that characterizes February starts to break.

South-facing windows remain strong performers, but the geometry is changing. The sun is now rising higher in the sky, which means it no longer penetrates as deeply into south-facing rooms as it did in December and January. Plants that sat in a broad band of direct winter sun near south windows may now be receiving indirect light as the sun angle rises. Check whether your south-facing plant positions are still optimal.

East and west windows are now delivering their best light of the season — the sun's angle and duration at east and west windows in late March produces genuinely useful morning and afternoon direct light. March is a good time to redistribute plants into east or west positions that couldn't support them in winter.

Supplemental grow lights can begin to be reduced in late March if your natural light is improving significantly. Don't rush this — many growers scale back too quickly and plants stall. Match the reduction to what you're actually observing.

Watch for heat through glass. As sun angle rises and intensity increases, south-facing glass can now transmit enough concentrated light and heat to scorch some tender leaves, particularly new growth. If you see whitened or papery patches on leaves touching or near south glass, move the plant back slightly.

Watering adjustments

March is when I start meaningfully increasing watering frequency, and I do it gradually, following the plant's signals rather than a calendar.

The rule I use: when I see a fully unfurled new leaf — not a node swelling, not an emerging cataphyll, but an actually opened leaf — I increase watering frequency for that plant. Before that point, I hold at late-winter levels. After it, I begin checking soil moisture more frequently and watering when the top 1–2 inches of soil are dry (for most tropicals) rather than waiting for the top 3–4 inches to dry as I did in winter.

For calathea and heartleaf philodendron, which prefer consistently moist (not soggy) soil per NC State Extension, I shift toward more frequent checks in March and do not allow full drying. For pothos and ZZ plant, which tolerate drying, I still allow more drying than I will in summer peak.

Drainage remains important. March is when I also check that all drainage holes are clear and that pots are not sitting in standing water in their saucers. Roots that survived winter dormancy in a relatively stable environment can be damaged by sudden waterlogging if drainage is compromised.

For help calibrating your specific plant and pot combination, the watering frequency calculator can walk you through the variables.

Humidity

As heating systems begin to run less frequently in March (assuming outdoor temperatures are rising), indoor humidity starts recovering on its own. This is a welcome change after the dry-air grind of November through February.

That said, heating systems in many Northern hemisphere climates still run regularly through March, and cold snaps are common. Don't dismantle your humidity setup — pebble trays, humidifiers, plant groupings — until you can see that your most sensitive plants (calathea, ferns, nerve plant) are no longer showing new crispy tip development.

Per NC State Extension guidance on supplemental humidity: qualitatively high humidity is still beneficial for tropical foliage plants during the transition period. March is not the time to declare victory and move on.

By late March in most climates, natural humidity is improving enough that strict humidifier management becomes less critical. But watch your plants rather than the calendar.

Pest pressure this month

March brings a new pest: thrips. Thrips (Frankliniella spp. and related genera, per UC IPM) are tiny, elongated insects that feed by rasping plant tissue and sucking the released contents. They are attracted to new, tender growth — which is exactly what most of your plants are producing in March.

The early signs of thrips damage are subtle: silver-gray streaking or stippling on new leaves, distorted leaf edges, and small dark fecal spots on foliage. Thrips themselves are small enough (typically under 2 mm) to be missed without close inspection — hold a white piece of paper under a leaf, tap the leaf, and look for small moving specks.

Thrips are particularly problematic on monstera new leaves, calathea, and tender vining growth on pothos and philodendron. They can also overwinter indoors and emerge with the new growth flush, so even plants that have been isolated all winter can show thrips in March.

Spider mites may still be present from winter — March is when you do a final winter mite inspection while also beginning to watch for thrips. These two pests require slightly different treatment approaches. See spider mites vs thrips vs whiteflies for detailed comparison.

Tasks for this month

Plants to focus on this month

Monstera deliciosa (Monstera deliciosa)

March is monstera month. The new leaf roll typically appears in late March in my experience — a tightly coiled new leaf emerging from the growing center of the plant. When I see it, I increase watering frequency and prepare to introduce fertilizer as soon as the leaf fully unfurls. New monstera leaves take 1–3 weeks to fully open depending on conditions.

This is also the right time to check whether your monstera is root-bound. Monstera roots are thick and assertive — if you see them circling the inner walls of the pot through drainage holes, or if the plant is wilting within a day or two of watering, it's time to repot. Go up 2–4 inches in pot diameter.

Monstera is toxic to dogs and cats via insoluble calcium oxalates per the ASPCA Swiss Cheese Plant entry.

Golden pothos (Epipremnum aureum)

Pothos is typically already growing by March, having started in late February. March is when I begin increasing its water from the "barely once every two weeks" winter schedule back toward every 10–12 days, and toward weekly by late March as growth accelerates.

If you want to propagate pothos — which is extremely easy to do from stem cuttings with a node — March through May is the ideal window. Cuttings root quickly in this growing window in either water or moist potting medium.

Per NC State Extension, pothos tolerates a wide range of conditions but grows fastest in bright indirect light with adequate water and fertilizer. March is when those conditions start coming together.

Toxic to dogs and cats per the ASPCA Golden Pothos entry.

Calathea (Calathea spp.)

Calathea wakes up slowly in March, but its response to improved humidity and light can be dramatic. Plants that looked bedraggled through February often begin producing fresh new leaves in March that are much more vibrant and less damaged than the winter foliage.

March is the right time to check whether your calathea needs a new pot. Calathea typically needs repotting every 1–2 years, and spring is the best time to do it. Use a well-draining but moisture-retentive mix (standard potting soil with added perlite works) and do not go dramatically up in pot size — too large a pot holds too much water for calathea's preference.

Non-toxic to cats and dogs per the ASPCA Calathea entry.

Heartleaf philodendron (Philodendron hederaceum)

If your heartleaf philodendron started showing cataphylls in February, by March it likely has multiple new leaves in progress. This is a fast-growing plant in the right conditions, and March conditions are right. Resume slightly more frequent watering and introduce fertilizer at half-strength.

Watch for thrips on the new tender leaves — heartleaf philodendron is a common thrips host in my experience, and the new leaves' softer tissue makes them preferred feeding sites.

Toxic to cats and dogs per the ASPCA Heartleaf Philodendron entry.

Peace lily (Spathiphyllum spp.)

March is when peace lilies often begin their spring bloom push. If yours hasn't bloomed in a while, March through April in a bright indirect light position is when it's most likely to produce flowers. Peace lily is one of the few tropical houseplants that tolerates low light while still occasionally blooming.

Watering: peace lily is more drought-sensitive than most of the plants on this list and will dramatically wilt when dry, then recover quickly when watered. In March, check it regularly and water when the top inch of soil is dry.

Toxic to dogs and cats via insoluble calcium oxalates per the ASPCA Peace Lily entry.

What NOT to do this month

Do not fertilize before you see new growth. The first warm day in early March is not a signal to fertilize. Fertilizer applied to a dormant or just-transitioning plant sits in soil and contributes to salt buildup without being used. Wait for the leaf.

Do not jump straight to full-strength fertilizer. Start at half the recommended dose and stay there for a month before moving to full-strength. This is particularly important after the long winter period where roots have not been actively processing nutrients.

Do not repot plants that are not showing signs of root binding. Repotting disturbs roots and requires recovery energy. If a plant doesn't need it, don't do it just because it's spring. The rule: repot when the plant is clearly constrained, not on a schedule.

Do not stop watching for winter pests while starting to watch for spring pests. Spider mites don't quit in March, and thrips arrive in March. You need to check for both simultaneously.

Do not move tropicals outdoors yet. Even if outdoor temperatures are warm during the day in March, night temperatures in most Northern hemisphere locations are still too cold for tropical plants. The general rule: wait until overnight temperatures are reliably above 55°F (approximately 13°C) before considering outdoor placement.

Frequently asked

When exactly should I start fertilizing in spring?

The trigger is a fully unfurled new leaf — not a swelling node, not a leaf still in the cataphyll, but a leaf that has actually opened and expanded. When you have that, you know the plant is actively growing and can use the nutrients. Start at half the recommended dose of a balanced liquid fertilizer and increase to full strength after the plant has had two to three successful weeks of growth. For most Northern hemisphere houseplants, this means late March to mid-April, depending on the plant and your light conditions.

What's the right pot size when repotting in March?

Go up one size — typically 1–2 inches larger in diameter than the current pot. The common mistake is going up too many sizes at once, which leaves too much soil volume around the root ball. That excess soil holds moisture the roots can't reach, creating waterlogging risk in the very areas farthest from the plant. A snug new pot that gives roots about an inch of fresh growing room is better than a dramatically oversized one.

My monstera hasn't shown any new growth yet in March. Is something wrong?

Not necessarily. Monstera growth timing depends heavily on light and temperature. In a north-facing room or a particularly cold apartment, the physiological signals that break dormancy take longer to accumulate. Give it until late March before worrying. In the meantime: move it toward your best light source, check that it hasn't been overwatered through winter (root rot will delay spring growth significantly), and confirm it isn't root-bound in a way that's compressing the roots. If by April 1 there is still no movement, inspect the root system and consider a soil refresh.

Sources: NC State Extension Plant Toolbox, NC State Heartleaf Philodendron, NC State Pothos, UC IPM Thrips, ASPCA Swiss Cheese Plant, ASPCA Golden Pothos, ASPCA Calathea, ASPCA Heartleaf Philodendron, ASPCA Peace Lily