120 Spider Plants Watering Experiment - The Setup.

I wanted to see if and how much does the outcome (21.65ml/10cm pot) from the greenhouse study translate to a home setting. The original study was done over a period of 3 weeks. I’m hoping to do this over a period of a year.

The Subject

 I’ve opted for Spider Plant (Chlorophytum). Total number of plants - 120. My reasons for this choice are:

·         It is a widely grown foliage house plant.

·         It is considered to be highly adaptable, tolerating heat, bright sun and shade.

·         Cost effective – you can harvest a lot of rosettes from a mother plant.

·         I could acquire samples from domestic environments; friends and home propagators.

·         Each rosette is reasonably consistent.

Variables

Setup

I’ve made plywood trays and lined these with plastic sheet to make my setups as standard as possible. I’ve got two labels to ensure that light, temperature and humidity is measured in the same spot every time. My bathroom shelf is definitely an outlier, so it will be interesting to see how it fairs.

Light

My plants are being grown in four different rooms near a window. This is where my trays come in giving me a more standardised spread, except in the bathroom. The windows positions are as follows:

·         Living room – 153° South East

·         Kitchen - 73° East

·         Bedroom - 327° North West

·         Bathroom - 327° North West

I’m using a DLI, Day Light Integral meter to capture volume of light plants receive each day. I’m also supplementing this with another light meter app.  There is a lot to discuss here, so I’ll save it for a more dedicated article, to avoid digression. 

Temperature and humidity

I am using ThermoPro meters with my sets, which collect the data 24/7. Quite impressed by their app for now, may change as I progress. Straight forward to set up and it captures info hourly for both of my variables.

Plant pot

I am using a (td)105mm x (bd)80mm x (h)80mm plastic pot for every plant. That’s a volume of 540ml. Each plant pot carries a label with a plant number, weight of the plant, number of leaves, roots length and a date.

Soil

All plants are potted in the same substrate, a multi- purpose compost for all plants, veg, trees and shrubs, enriched with 4-5weeks of feed. The same amount of soil (171g) is used per plant.

Plant matter

Each plant is weighed, leaves counted, and roots measured to be used later for comparison.

Water

I am using tap water. Not everyone has access to a water butt and when it comes to watering in winter, I certainly rely on tap water. I am based in the UK and the water in my region is Moderately Hard with an average pH of 7.23.  I do however allow the water to stand over night and then capture its temperature at the time of watering.

Air circulation

I wont be adopting any fans. Instead I will be relying on normal, human day to day behaviour. If it's hot and stuffy I'll open the window, if it's cold I'll close it.

Plant watering schedule

Plants in the University of Georgia & University of Maine study received 21.65ml/10cm pot every day. Here is the watering schedule I’ve devised.

The first will explore:

·         Is it 21.65ml every day - I've rounded up to 22ml for ease and I'm also less likely to make an error with round numbers over long term.

·         Or can I use the total amount of water per week averaged across the number of waterings in a week. This will allow to see the impact of drying periods between waterings? - I've rounded values for ease.

The second will explore:

·         How the plants respond to the different volumes of water outside the 21.65ml discovery without a drying cycle. I’m looking at the extremes of underwatering and overwatering.

Predictions

1. Will it be 21.65ml per day? - I think it will be more. Average commercial greenhouses are run at temperatures of 18-24°C (64.4 - 75.2F) not that dissimilar to homes. However, they are much more humid, with relative humidity being generally kept at 80%. UK homes recommended humidity level is 55% for a healthy, mould free home. This will have an impact on needing more water. Of all my window setups, I recon my south east living room set will be the closest in value and the north west bathroom set will be the furthest.

2. Will the plants with a drying cycle need less water, all the water they are given or more water then the watering schedule allows? – I suspect that plants with a drying cycle will need all the water they are given during their watering schedule. Not less, not more.  

3. Will the drying cycle have a beneficial impact? – Plants that are watered once a week will be the most successful across all sets. Less frequent watering will retain soil nutrients and allow for water logging to dissipate, giving roots more oxygen.

4. How will plants fair on underwatering and overwatering schedule? – The light and temperature will have the biggest impact here.

   
   

   1. South East Living Room and East Kitchen sets – Plants that are being watered 8ml a day will perform the worst. Second place will go to 64ml, as I think all that water will wash out all the nutrients. 24ml set will perform the best.

   2. North West Bedroom & Bathroom - These sets will have a significantly more stunted growth. Plants that are being watered 8ml and 16ml a day will perform the best. The rest will just get sodden and washed out. I think Bathroom set foliage will fair better due to humidity, less dry tips.

Measuring Success

I will be looking for healthy foliage, leaves that are stiff and deep in colour, with good additional growth. Roots will need to be white and plump. I will accept some level of dry tips as long as the rest of the plant looks healthy.

That's it. Let me know if you have any hypotheses or things I've not considered with regards to performance or setup.

Essentials For House Plants Watering

The Fazeley Flow

Haws Watering Can

Small, but big, watering can for pinpoint watering accuracy. And if the research is right, it can water 27 plants in one go!

Volume: 1 Pint / 568ml

Dimenions: L31 x W11.5 x H11

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Welcome to The Plant Notebook

My name is Anna and I'm a maker with an interest in plants. I run Horticus from my pottery studio in Leicester where I make my living wall kits, write about indoor gardening and dabble in fun experiments.

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