We got tired of being told to "water when dry." So we built the math.

Who We Are

PlantSolve is an independent plant care platform focused on practical, evidence-based guidance for houseplants, aquarium plants, and indoor gardening.

The site combines botanical research, horticultural references, real-world growing experience, and software-driven tools to help plant owners make better care decisions.

Content is published under the PlantSolve Editorial Team and follows the editorial standards described in our Editorial Policy.

The problem with standard plant advice

Generic plant advice is written to be universally applicable, which means it's specifically useful to no one. "Water every 7 days" ignores pot material, pot size, light intensity, room humidity, and season — four variables that can shift a plant's actual water need by a factor of 3× or more. "Place in bright indirect light" tells you nothing useful in a north-facing apartment in Edinburgh in November.

After building calculators and diagnosing thousands of real plant problems submitted through our tools, we have catalogued the failure patterns that generic advice misses:

• Overwatering is the number one cause of houseplant death, and it is almost always caused by schedule-based watering that ignores environmental variables.
• Root rot cases spike 40% in winter — not because plants are watered more, but because soil takes 2–3× longer to dry in low-light, centrally heated rooms.
• The single most common reason a plant fails after a home move is not water — it is a directional light change that triggers the plant to shed leaves calibrated to its previous environment.
• In AC-cooled homes during summer, most tropical plants need water 30–40% more frequently than standard care guides suggest.

These are not opinions. They are patterns derived from structured data, horticultural literature, and the diagnostic outputs of our own tools. This is the gap PlantSolve was built to close.

How our calculators are built

Every PlantSolve calculator is a structured model, not a lookup table. Here is the exact methodology applied to our most-used tool, the Watering Calculator, which also describes the standard we apply across all tools.

01. Source the baseline data from peer-reviewed horticultural science

Base evapotranspiration rates, species-level water uptake coefficients, and light-response curves are sourced from peer-reviewed horticultural literature, including work published in HortScience, Scientia Horticulturae, and USDA extension research. Aquatic plant nutrition models additionally draw from planted aquarium science literature, including the work of established aquarists and plant biologists in the planted tank community.

02. Build the variable model around real home conditions

Lab-measured evapotranspiration rates are measured under controlled greenhouse conditions. A home is not a greenhouse. Our models add correction factors for: pot material (terracotta loses 20–30% more moisture per day than equivalent plastic), pot-to-plant ratio (a small plant in an oversized pot retains moisture far longer than the same species in a correctly sized pot), ambient humidity (homes with central heating drop to 20–30% RH in winter versus 50–60% RH in summer with open windows), and light intensity (photosynthesis rate directly controls water uptake demand). These correction factors are validated against published horticultural extension data and adjusted iteratively using real-world user feedback from our diagnosis tools.

03. Test outputs against known failure cases

Before any calculator is published, outputs are tested against documented plant failure scenarios: a Calathea in a terracotta pot in a 68°F heated room should need water every 3–4 days in winter. A Sansevieria in a large plastic pot in low light should need water every 21–28 days. A Monstera in a 10-inch plastic pot in bright indirect light with 50% RH should need water every 10–14 days in summer. If a calculator's output deviates from these known-correct benchmarks by more than 15%, the model is revised before publication.

04. Document assumptions explicitly in each tool

Every calculator includes visible notes about which variables it accounts for and which it does not. If a tool assumes a stable indoor temperature of 65–75°F and your home regularly hits 85°F in summer, the tool will note this limitation. We treat undisclosed assumptions in plant care tools as a form of misinformation — a calculator that produces confident outputs without stating its limits is more dangerous than no calculator at all.

05. Update models based on diagnostic data and seasonal corrections

Tool outputs are reviewed quarterly and updated annually. Seasonal corrections (winter heating desiccation, summer AC effects) are updated each June and November. When diagnostic tool usage patterns identify systematic misdiagnoses — for example, a spike in users reporting "overwatering symptoms" during winter that are actually caused by cold root shock — the affected calculators and guides are revised to account for the misidentified pattern.

What PlantSolve covers

Indoor plant care

Species profiles, watering schedules, light requirements, humidity management, soil and potting mix guides, and seasonal care adjustments for tropical houseplants, succulents, cacti, flowering plants, and rare aroids. Primary focus on Western home environments — centrally heated in winter, AC-cooled in summer.

Aquarium plants

Care guides, CO₂ and fertilizer dosing calculators, substrate recommendations, and species compatibility guides for planted freshwater aquaria. Fertilizer dosage models are based on the Estimative Index and PPS-Pro dosing methodologies established by Tom Barr and Greg Watson respectively.

Diagnosis tools

Structured symptom-to-cause diagnostic tools covering overwatering, underwatering, heat stress, cold shock, nutrient deficiency, root rot, and the 11 most common indoor plant pest species. Diagnosis outputs link directly to treatment guides and corrective calculator adjustments.

Fertilizer and soil reference

NPK ratio reference library, organic fertilizer guides, potting mix calculator, and soil pH adjustment reference. Fertilizer chemistry is sourced from plant nutrition science standards, not product marketing materials.

What we separate from plant care science

PlantSolve deliberately separates plant health requirements from styling preferences, symbolic placement traditions, and wellness claims.

Vastu and directional placement

We publish Vastu plant guides because they are a genuine cultural tradition with widespread practical interest. However, Vastu placement recommendations on PlantSolve always come secondary to a plant's actual growing requirements. A plant that requires south-facing bright light to survive will never be recommended for a north-facing room solely because it is considered auspicious there. The plant's biological needs take precedence.

Wellness and air quality claims

We do not claim that houseplants meaningfully improve indoor air quality in typical room volumes, because the evidence does not support this at realistic plant densities. The widely cited NASA Clean Air Study used plant densities far higher than any home environment. We cite what the research actually shows, not what plant marketing materials claim.

Aesthetic and styling advice

Arrangement guides and styling content are clearly labelled as preference-based, not care-based. A plant's appearance in a photograph does not determine its care requirements.