30 July 2009

The Pansy Chronicles - More Pansies!

Four weeks ago I sowed a packet of seeds and now look at them!

This particular mix of Pansies is my seed crop for the course in Greenhouse Management. The ultimate goal is to produce a commercially viable crop to sell at our fall plant sale. Lest you think it's just a matter of water and fertilizer, let me tell you what all goes on in Pansy-Land.

We sowed the seed and placed the trays on the mist bench until we saw signs of germination (about 6 days). The trays were then whisked off to our assigned benches for growing on. Once the cotyledons, or seed leaves, were all present and accounted for - and even some of the first sets of true leaves (about 9 more days) - the teeny seedlings were pricked out to cell flats (a plastic liner consisting of 12 6-packs).

Gavin demonstrates the fine art of transplanting seedlings My requisite three trays (July 17) with some to spare

Once the newly transplanted seedlings had some time to acclamate to their new surroundings, the science of Pansy growing began. Each week we engage in a ritual known as root media pH and EC monitoring. Huh? Soil pH is a measure of the acidity or alkalinity of the soil substrate. Measured on a scale of 0 - 14, 7 is neutral. Anything less is acid, anything more is alkaline. Soil pH can be adjusted up or down by the addition of certain elements. Pansies happen to enjoy a bit of an acid trip and prefer a pH between 5.4-5.8 for the type of root media we're using.

And what is EC, you ask? EC stands for Electro-conductivity. Simply put, it's a measure of the soluable salts in the soil solution (say that five times fast!). You see, soil nutrients are present in the soil solution as charged ions. There are positively charged ions called 'cations' and negatively charged ions called 'anions'. The nutrient ions are transferred across the negatively charged root surface into the plant cells. Too much salt (high EC) impedes this exchange which can, in turn, negatively influence plant growth by burning the tender root tips, which further restricts water and nutrient uptake.

Conversely, too little salt (low EC) and the plant will suffer from lack of fertilizer. Nitrogen and Phosphorus in particular are not taken up by the plant and it becomes malnourished, stunting growth.


Think of it this way, Pansies like it 'just right' so we monitor the pH and EC to keep it that way. This entails saturating the root media, collecting the leachate (water that runs out the bottom of the flat), measuring the amount collected, then testing the EC and pH with a handy-dandy little probe, and adjusting our fertilizer regime accordingly. Tracking the numbers this way allows us to make adjustments before the plant begins exhibiting outward signs of nutrient stress.

As if that weren't enough, we have the additional challenge of growing this crop in the greenhouse. In the middle of summer. When a power outage caused the greenhouse to reach 102 degrees F. The trick is not to let the plants get too tall and leggy, which is a balancing act between the amount of fertilizer, temperature, and light.

Don't get me started on Plant Growth Regulators; trust me, you'll be sorry.

The same plants as above (July 29)

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