Growing Plants From Seed


I used commercially grown starter plants for my first attempt at hydroponics, but it's much better to grow your own starter plants from seeds. You won't have insects like white flies that are common in nursery grown starter plants, nor will you have the occasional viral infections like tomato mosaic virus. Less time is spent starting seeds than would be spent making a trip to buy plants, and the seeds can be started any time you're ready as opposed to starter plants which are only available in the spring. You'll save money starting your plants from seeds. Best of all, growing plants from seeds is fun.

One popular technique for starting seeds uses rock wool starter cubes. This method is appropriate for almost any type of plant. Some plants with larger seeds can be started by simply poking the seeds into the growth media. For this to be successful, the upper surface of the growth media must be kept moist at all times.

Better results are usually obtained with the rock wool starter cubes. However, I experimented with starting small seeded plants such as lettuce and basil, both in rock wool starter cubes, and simply by spreading the seeds on the growth media and attempting to germinate them without any extra effort. I'm always looking for an easier way to grow produce. The fewer steps in the process the better.

I also experimented with the concentration of the nutrient solution. Lettuce requires half strength nutrient solution compared to crops like tomatoes or peppers. The most convenient measurement of nutrient strength is electrical conductivity, as measured in micro Siemens per centimeter. Lettuce prefers an EC of 800-1200 uS/cm. I planted basil in the same container to see how well it would grow on the half strength solution. Ultimately, this planter box will grow only one crop, but I thought I'd try to grow half a planter of basil just to see how well it would grow. A little later, I'll plant a lot of basil in another planter box.

There isn't much to see in this picture. I set up another EZ Flood & Drain hydroponic system on a southeast facing window, hidden behind a chair in the living room, and placed eight rock wool starter cubes in the growth media. The left half contain leaf lettuce, the right half contain sweet basil. As an experiment, I also sprinkled about a dozen of each type of seeds in the growth media around the rock wool starter cubes to see if they'd germinate.

The nutrient solution is half the normal strength to prevent burning the lettuce. I'll evaluate how well the basil grows with the less concentrated nutrient.

The recommended method of using rock wool cubes is to soak them in rock wool conditioner to correct their pH, then germinate the seeds by soaking the cubes in a tray of water (not nutrient solution) for a few days. Being lazy, I soaked the rock wool cubes in the nutrient tank solution for maybe an hour, then plugged the cubes into the growth media and planted the seeds. We'll see if they germinate and grow.

3JUL03



I had the bright idea of covering the entire planter box with clear plastic wrap to keep the top layer of the growth media moist to encourage the seeds to germinate. The rock wool retains moisture and almost certainly wouldn't be a problem, but I wanted to give the seeds spread on the growth media a decent chance. Rock wool starter cubes buried in growth media only need to be watered once a day unless conditions are very hot or dry.

The plastic film technique probably wouldn't be very good for germinating seeds in most home hydroponic gardens. Most of the time, a head of lettuce will be harvested when it's mature or the final leaf lettuce harvest will occur when the plant growth slows, but seldom will an entire planting bed be harvested and replanted again. However, a commercial operation will plant an entire planter box at once, so this may be a good way to germinate seeds without the expense and hassle of starter cubes, provided a reasonable percentage of the seeds can germinate near the surface of the growth media.

4JUL03



There were a couple of small lettuce sprouts on the rock wool starter cubes after only one day. That's fast. Tomato seeds take about a week to germinate, and pepper seeds can take about two weeks. Nothing yet visible from the seeds that were scattered on the moistened growth media.

New life. I need to keep reminding myself that I don't have godlike powers, producing life where none previously existed. Actually, I'm humbled to be present when new life leaps toward the light.

Another way in which my behavior is anything but godlike – I expect to be eating these guys in the near future.

4JUL03



Day four. All the seeds in the rock wool starter cubes have apparently germinated and are growing well. Almost all of the seeds that were sprinkled on top of the grow media have also germinated but are developing more slowly at first than the seeds that were planted in the starter cubes. If you look closely, you can see a small lettuce seedling growing between the starter cubes. The picture shows the lettuce seedlings, but the results are the same for the basil.

Even with the obvious improvement in growth with the rock wool starter cubes, so far I prefer the idea of germinating the seeds by planting them directly in the growth media. It's significantly easier than the multistep rock wool method, and there's one less item to buy and inventory.

I'm concerned that the seedlings will rot from direct contact with the wet plastic. Frequent flooding to the top of the growth media will probably keep the media moist without plastic but will result in algae. A piece of plexiglass over the planter box that won't droop down onto the seedlings might be better.

7JUL03



Day five. Here's the lettuce again. The rock wool seedlings are still growing much faster than the seeds in between the rock wool cubes that were germinated directly on top of the growth media. Smaller rock wool cubes might be a good compromise between the better hydration that rock wool provides, and the lower cost and hassle factor of sprouting seeds directly on the perlite / vermiculite growth media. I'll try starting seeds in the 1/2” cubes instead of the 1” X 1” X 1.5” cubes I've been using.

The plastic wrap was removed for this picture, but was replaced to keep the seedlings moist. The plastic was taped to the ends of the planter box to keep it from sagging down onto the new seedlings. A piece of 1/8” thick plexiglass would probably be a better option, but the plastic film is cheap and fairly easy.

8JUL03



Day nine. Here's the zoomed out view. The lettuce and basil are both making good progress. The plastic wrap has been off a couple of days. The growth media is flooded up to the very top to make sure the surface stays moist for the benefit of the seedlings not started in rock wool. Particularly if not using rock wool, it's important to make sure that the growth media is very level so the surface is uniformly watered. Otherwise, the plants in the valleys will be submerged while those on the peaks might dry out.

All plants are doing well, but the rock wool seedlings are still well ahead of the others.

12JUL03



Day 14. The leaf lettuce is coming along nicely. It's been flooded to the very surface with nutrient solution about three times a day, pH: 7.0, EC: 1200 uS/cm.

The lettuce looks very light green. I guess that's normal for lettuce?

The pH was corrected today to 6.5.

17JUL03



Day 14. The basil looks nice too. Note that, like the lettuce, the seeds started in the rock wool are still maintaining a healthy lead on those that germinated near the surface of the vermiculite / perlite growth media. Surprisingly, the seeds all seemed to germinate, regardless of whether the rock wool cubes were used, but the rock wool seeds germinated faster and continued to grow faster in the first two weeks.

Now that the plants are becoming well established, I look forward to seeing how quickly they'll grow.

17JUL03



Day 20 - Lettuce

23JUL03



Day 20 - Basil

23JUL03



Day 23 - Lettuce

26JUL03



Day 23 – Basil

The perlite and vermiculite growth media is lower on the basil side. It has been repeatedly flooded to the top surface. Water + nutrients + sunlight = algae. The algae doesn't hurt anything. There are plenty of nutrients to go around. But it is a bit ugly. To prevent algae growth, keep the top level of the growth media level, and never flood the surface with nutrients. Fill only to within half an inch of the top of the surface.

26JUL03



Day 26 - Lettuce

The exponential growth is really taking off now. The lettuce and basil are both good for low light hydroponics, using only the sunlight available in a south facing window. Notice the poor growth on the left, caused by the left side of the planter box receiving less light because of the orientation relative to the window.

29JUL03



Day 26 - Basil.

Also growing nicely. Both the lettuce and the basil seem to have a growth rate of about 10% per day, as a rough guess. The basil smells really good.

29JUL03



Day 30 - Lettuce

The lettuce is starting to turn a little greener as it grows. At this exponential growth rate, it should be ready for harvest in about two weeks.

2AUG03



Day 30 - Basil

The basil looks very healthy. At this rate, it should also be ready for harvest in about two weeks.

If I plant eight basil plants, each a week apart, I should be able to harvest a basil plant every week. A four plant rotation would allow me to have fresh basil every two weeks, which is probably about right.

I'd like to rob a few leaves and not harvest the entire plants, but I suspect they'll go to seed soon after eight weeks.

They already have a wonderful basil smell. There's a very faint whiff of basil nearby, but the essential oils rub off the leaves onto my fingers and it's very fragrant.

I'd like to try a couple of other varieties of basil too. This is sweet basil, but I also have Thai basil and Genovese (Italian) basil seeds.

2AUG03



Conclusions:

The basil and lettuce both grew very well, despite having somewhat different nutrient requirements. Even though both plants require little light, I think they'd have grown a little faster with a bit more light, and the plants would have probably stayed shorter and bushier. All the seeds that were planted appear to have germinated, but the plants in the rock wool starter cubes grew consistently larger. The other plants never caught up to the rock wool plants. I wouldn't bother with covering the planter box with plastic to retain moisture at the surface to improve germination. From now on, every place I want a plant I'll put a rock wool starter cube with one seed. I'll plant one lettuce and one basil plant every week so they'll mature when I want to eat them.

The Sweet Basil and the Simpson Black Seed Lettuce were both good, and I enjoyed being able to have fresh lettuce and basil whenever I wanted it and not needing to buy it at the store, and find it was going bad in the refrigerator when I decided I wanted to use it. The lettuce leaves were very delicate, possibly due to the low light, possibly the calcium in the water or the higher than optimal pH, or something else. It wasn't a problem, and the lettuce taste and texture were quite good. Most of it was eaten on sandwiches. It was nice to have large, fresh, green leaves of lettuce, rather than the inferior store bought variety. But I think I'll experiment with different varieties of lettuce. I'll also grow the lettuce in its own hydroponic system and I'll optimize the nutrient concentration and pH for growing lettuce. But the produce was quite good, and I really don't have any complaints. The plants started off slowly, but the growth rate after one month was very rapid. Check here if you'd like to see what to do with all that basil.