Nobody's Mad

Today was unusually cool for Mariposa in June. Overnight low was 55 and daytime temps were mostly in the low 70’s, briefly reaching 80 around 5pm.

We’re hopeful that the cool temperatures will encourage the lettuce we planted yesterday to germinate.

Most of our early starts failed to germinate. We believe this was due in part to insufficient moisture, as the swiss chard finally germinated after we watered heavily. There may also have been a problem with the compost-based potting soil pH, as it turns out that our pH meter is worse than useless.

The swiss chard, and a second wave of radish, germinated nicely after heavy watering. However we then lost about one seedling per night. We finally tracked the problem down to a lone earwig, which was biting the young shoots just below the first leaflet. Since sending the earwig to meet its maker we have lost no further seedlings – but all that we have left of the early starts is four radishes.

Today we planted the main wave of starts, about two weeks before we take them to Seattle. In all we planted four seed trays of 72 cells each, most with two seeds per cell. I’ll create separate posts with the precise details. We used a premium commercial potting soil this time.

Common Earwig

Last night, I went to look at the potting tray about 1am.  I found a small earwig nibbling the last remaining swiss chard just below the leaf. The earwig ran off and today that seedling looks like the others.

According to Wikipedia, earwigs look for dampness during dry weather, and their diet includes tender shoots and seedlings.

Our potting mixture is too deeply colored to get a pH reading from a regular garden soil test kit, so we bought a pH meter – actually a Moist/Light/pH meter.

The extremely low germination rate and sickly behavior of seedlings made us suspect the soil pH.  So we tested the pH meter.

Testing tap water, the meter reads pH 6.7 with an inch immersed and pH 5.2 with four inches immersed.  Our regular garden soil test kit yields a pH of 7 for our tap water.

We were unable to attain deep immersion in a compartmented potting tray, so we filled a jar with potting soil and added water.  The meter read ph 5 with an inch immersed and initially pH 3 with four inches immersed.  After a few minutes the four-inch reading dropped to pH 4.5.  There may be pH changes as the various components of the potting mixture react with the water.

We removed potting mixture from several cells of the potting tray and arranged it so as to be able to test at various immersions.  At one inch the meter read pH 6.2 and at four inches the meter read 5.2.

Testing tonic water, the meter read pH 5 with an inch immersed and pH 3.5 with four inches immersed.  The pH changes steadily as immersion increases.  Clearly the pH meter has insufficient impedance.  We tried dissolving various quantities of table salt in the tonic water but there was little change in the readings.

We tried testing the tonic water with our regular garden soil test kit.  The pink solution and buff precipitate don’t match any standard reading so we don’t know precisely how acid the tonic water is.

I wish I could tell you the brand name of our Moist/Light/pH meter but all it says is “Made in China”.  It is green and has two probes.  And the pH function is garbage.

Two of the “moist paper towel” radishes planted yesterday have developed nice shoots with small green leaves or cotyledons just at the surface of the potting soil.

Additionally, there are growths from one other “moist paper towel” radish and also two of the “jar of water” radishes but these growths appear to be confused roots (radicles) rather than shoots. It was not possible to properly orient the germinated seeds during planting but I had expected the radicles to be more sensitive to gravity (geotropic). Perhaps I soaked them too long (24 hours) before planting.

After 24 hours, 7 of 10 radish seed in a jar of water and 8 of 10 on a folded damp paper towel in an inflated ziploc had germinated. Those in the jar of water germinated about six hours ahead of the others. All 20 have now been planted in potting soil.

The seed coats of those which had been in the jar of water were much more delicate than the seed coats of the others. A couple of the seed coats from the jar of water fell off during planting.

Thus far the only seedlings to appear have been the Swiss Chard, with 10 out of 18 (56%). Time for some germination tests.

One test has ten radish seeds on a folded moist paper towel in an inflated ziploc bag, indoors in the dark, with temperatures in the 70’s. The seeds are not covered by the paper towel so we can see them. Upon germination they will be planted in moist potting soil.

The second test has ten radish seeds in a jar of water, indoors in the dark, with temperatures in the 70’s. After 24 hours of soaking they will be planted in moist potting soil.