More great feedback from GrandmaGos

When your seedlings all have at least 2 sets of true leaves and are ready to pot up and be given to friends, put each one in an 8 oz styrofoam coffee cup with a couple holes punched in the bottom with a pencil. Styrofoam coffee cups are endlessly reusable for plants as long as you don’t crack it, and you can write the name on the outside with Sharpie.

If the MG potting soil says “feeds for 3 months”, then you can start adding some half-strength fertilizer after about a month. It’s a really tiny amount of fert that they include, it’s mostly just there to look good on the label.

Always cut potting soil with about 1/4 to 1/3 of some kind of lightener such as perlite or vermiculite. Used straight out of the bag, it tends to be very dense, moisture-retentive, and slow-draining.

Sometimes those modular plastic pots, with the attached saucer, will actually allow you to snap off the saucer. You have to kind of work with it, prying it with a screwdriver, but they do frequently come off.

I did manage to get the bottom of the pot off. I will try watering from the bottom as recommended here, using the 2 knuckle method. Note also that it should be watered from the top once a month to rinse down salts and things.

What Is Bottom Watering: Tips On Watering Potted Plants From The Bottom

Lots of advice from GrandmaGos on r/gardening

Correct watering procedure is to add enough water so that it comes out the bottom drainage hole. If you only ever water by pouring a small amount on top, two things happen.

  1. Since the water is always all up at the surface, root systems remain shallow, and don’t grow deeper in pursuit of water. Deep roots is what gives a plant reserves for a drought event, such as when you forget to water. If the roots are all up in the top layer of soil, then when that top layer dries out completely, they’re toast.
  2. Watering flushes out accumulated fertilizer and mineral salts from the soil. If you always add the same small amount of water, it carries these salts down to the same level in the soil every time, and eventually you end up with a layer of salts. In a terracotta pot these will come out through the pot wall, appearing as a layer of crusty salts on the outside. You can also get salts on the surface of the soil.

So what you’re currently doing for watering–adding only a small amount on top that isn’t enough to flush an 8″ pot–probably isn’t overwatering. What is happening is that the seedlings’ roots are shallow, since “on top” is where the water is, so when the top layer of soil is dry, that’s a drought event, and out of a potful of seedlings, one of them is handling it worse than the others, which is how natural selection works.

An 8″ pot is too large to start basil seeds in. The excess unused wet soil with no roots in it can go anaerobic as the water carries soil particles downwards and compacts them, removing air spaces between them. Next time, use something like an ordinary 2″ to 4″ pot, and figure on thinning and transplanting.

I’ve been looking at your plant diary. In your situation, you need as much light as possible on these, so I’d bring back the reflector. Mylar or white works better than aluminum foil.

Honestly, you’re wasting too much time on trying to do the math to calculate whether your plants are getting enough light. Don’t do math–just observe your plants. As they grow, they’ll tell you.

CFLs are fine, but you can load them up without having to worry about scorching and too much light. It’s the people using high-output marijuana grow lights like metal halides and multiple arrays like a 4-tube T5 or T8 that have to worry about scorching. If you’re working with ordinary table lamp bulbs like CFLs and LEDs, it’s not usually an issue unless you get, like, dozens of them all lined up.

If you have a tiny seedling so close to a CFL or other fluorescent that the leaves are actually touching the tubes, it can scorch, but otherwise you want the leaves to be 2″ (yes, two inches) from the light. Get a ruler and measure it. It’s right up under there, yes.

A two-tube T5 fixture is so much easier to work with than a flock of single CFLs in household lamps, it expands your options quite a bit, and it doesn’t take up that much of a footprint on the table or shelf.

I’d look for 100 watt equivalent on the CFLs if your light fixture can handle it, and I’d also look at 100w equivalent LED household bulbs. They tend to be on the heavy side in something like an architect lamp, but you can move the pot to where the bulb can shine on it.

Plants can be grown under lights 24/7, but most people shut off the lights at night for human reasons. If basil starts to flower too early, just pinch off the flower buds. You’re not growing weed here, where you need to manipulate the day-length in order to manage a flowering sequence.

You thinned your basil too early. Generally you wait until they all have at least two sets of true leaves. This gives you a much better handle on which ones are the strongest keepers.

I don’t see it mentioned, but if you don’t have one yet, get a cheap lamp timer to run the lights, it’s so much easier than having to remember when to shut them off.

Also, don’t move them around from window to window. Every time the lighting changes, the plant has to adjust its leaves, which wastes energy that it could be spending on growth. Pick a spot and leave it there.

Was your Miracle Gro potting soil that kind that says “feeds for 3 months” on the label, or says that it includes MG plant food?

Pfingis is sick :(

The plants are mostly looking good, but I noticed yesterday that the true leaves on Pfingis are dying. I’m not sure what is the cause. Possible explanations:

  • Over watering leading to fungal disease. I think this is the most likely cause. I may have over watered a little too much as it’s been several days and the top layer is still moist.
  • Aluminum reflector causing a hot spot. I doubt it, but Pfingis was near where I might guess the focal point would be for the cylindrical reflector, and it was a sunny day.

I’ll post on reddit to see if anyone might be able to help diagnose.

The CFL light seems to be working pretty well. I decided to ditch the reflector as I don’t think it helps much, anyway, especially with the CFL, and also since there’s an off chance that it hurt Pfingis, but I’m open to bringing it back in the future.

New lighting

Last year I tried to (have Cara) move the plant from the kitchen window to the front window mid-day, but even the back window only gets a couple hours of light in the morning due to neighboring buildings. What I’ve been doing this year so far is putting them under a standard LED (60 W equiv, see early post) after the sun goes down. According to this answer, the plants can be lit for about 12 hours and not encourage flowering (not that this matters, yet). So it should start getting some ambient light maybe around 10 am, but no full sun until 1 or 2, then I can run it under the lamp in the house until midnight or so.

I picked up a couple of the following CFL bulbs from Amazon:


  • Compact fluorescent spiral bulb provides the light you need while reducing energy costs
  • 26-watt/6400k bulb is equivalent to a 130-watt incandescent bulb
  • Produces 1600 lumens and will last an average of 10,000hrs
  • Maximum wattage of 26, color temp 6400K, medium base type, 130-volt
  • This product weighs 0.3-pound
  • 26 watt bulb is equivalent to a 130W incandescent bulb
  • Produces 1600 lumens and will last an average of 10,000 hours

According to this (it’s for cannabis, but I think basil is close enough to share the same preferences),  you can’t get CFLs too close to the plant (as long as it’s not overheating them).

Following the calculation in the previous post

Amazon says this light is equivalent to a 130 W conventional bulb, which would outputs approximately 100 W of total flux. At what distance is the irradiance equal to that of the sun, 1000 W/m^2?

sqrt(100 W / 1000 W/m^2 / 4 / pi) = 3.5 inches.

In the current configuration, the plants are probably 5-7 inches away, so they could be pulled closer but I’m a little afraid of heating. I’ll keep going with the current setup for the time being and see how it goes. The reflector probably helps a little, too.

The plants themselves are looking good. The first set of true leaves are just starting to take off. They look green and healthy.

Displaying IMG_2207.JPG


Birthday massacre

The sprouts were looking pretty strong, with the tallest ones a little over an inch high. It was my birthday, so I decided to go ahead and do the thinning.

I started by locating the tallest one, henceforth known as Zeuss, then cutting down all the basil within 2 inches. Then I looked around for the tallest one near the perimeter of the 2 inch zone, and repeated until I had 8 plants left. Some are close to the edge, which isn’t ideal, but I think they’ll be OK. Overall, I cut down about 125 sprouts.

Cara helped me assign names to the 8 remaining plants.

Sprouting like crazy

Sprouts are going nuts. I estimate about 100 in all. Most of them are getting close to 0.5’’. At about 1’’ I’ll thin them out. The remaining ones should have at least 2’’ of space (make a shape out of paper, or glass rim, of diameter 4’’? Could use a string, too). The algorithm that I think I’d like to try is to clear out space around the best looking one. Next, find on the perimeter that is second best and clear that one out. Continue searching on the perimeter. Can use some discretion if promising ones are near the perimeter. More pace probably OK.

I also added an aluminum foil reflector to help get a little more light in, especially to the sprouts in the the shadow of the pot (soil too low). Estimates around the internet show that the dull side (better than the shiny side) has higher reflectivity, maybe 60% at best. Mylar would be better, but this should be good enough. I’ve considered a mylar curtain behind the regular curtain.

The sheet, as is, is higher than it needs to be for now, but a full grown plant will use most of it. I really need to set aside some time to come at this problem from an illumination point of view. If I could make these things affordable, they might make some money. Passive illumination (no light required. Double the amount of sun your plant (by illuminating both sides), in a window, without needing to move it.

At night I shine a standard household LED bulb at it (60W?). Doesn’t take much away from the room, and I think with the reflector, gets at least some lighting.


Oh, and I rotate it 90 degrees every night before bed. Looking down from the top, I rotate the reflector 90 degrees counter clockwise.

Handbook of Optical Metrology: Principles and Applications


60W lightbulb -> 45 W of flux. Light is about 1 m away. Surface area is 4 pi r^2 = 12 m^2.

So power density is 45 W / 12 m^2 = 4 W / m^2


Sun: 1000 W/ m^2


Ok, so a meter away is basically useless. Invert the equation and try again.


sqrt(45 W/ 1000 W/m^2 / 4 / pi) = 0.06 m = 6 cm, or about 2 inches. So it has to be really close.

Quarter of the power at 4 inches.

Initial planting

Bought a cheap 8 inch pot and filled it with miracle grow indoor potting soil to about 0.5 inches from the top. Sprinkled sweet basil seeds around, then covered with a quarter inch of soil. Watered it with a large glass of water and it compacted down a bit so the top of the soil is now about 1’’ from the top (maybe should have watered soil first?). Sitting in the sun now, here we go!

Basil Recipe


Last Frost in Newton: May 24

First Frost in Newton: September 19

(10% chance of frost falling outside these dates)



  • Sun: 6-8 hours
  • Soil: Well-drained
  • Start 6 weeks before last frost (~April 10)
  • After final frost of the season, or start it inside?
  • Start off in large bucket, sprinkle seed packet.
    • Need to look up details on how to do that.
  • Once sprouted and 1’’ tall, thin them out to give each 2’’ of space
    • Thin by cutting, not pulling, to keep roots of neighbors intact.
  • Once 3’’ tall with first set of true leaves, transplant to separate pots. 6-8’’ of space per plant.
  • When plant has 3-5 sets of leaves, cut the top off just above the 2nd set of leaves from the ground.
  • Every 3 weeks or so, cut off above the first or second set of leaves on each new branch.