Issue 6


Table of Contents:


1. More About Strawberries

Plants grown under lights only (no daylight) have individual needs. Flat leaved plants like strawberries can get all the light the leaves require because they don't shade each other. But with tomatoes, only the top-most leaves get the desired amount of light. All the leaves below get very little light. Actually the leaf at the top gets most of the light.

So with strawberries the amount of light depends upon the cultivar you're using. Some cultivars don't care how long the day or daylight lasts. You can get by for both growing and fruiting with 12 hours of light.

Other cultivars take less than 12 hours of light, whereas there are also those which need more than 12 hours. But all of them have to have their "rest" or periods of darkness in order to fruit and flower. Reflectors are an excellent addition because they throw light back to the lower leaves.

Different lighting techniques for the two main stages of growth. Metal halide lamps are just right for the vegetative state when the plant is growing and putting on structure. For flowering (and result- ant fruiting) you need the sodium (high pressure) lamps. It's best to use the metal halide until you notice beginning flower buds.

Chilling is necessary:

No matter which cultivar you use, it will require some chilling. Too little will cause the plant to produce only runners. Too much and you get runners again and no fruit. A rule of thumb is 6-7 weeks of the kind of temperatures they would experience if they were planted out- doors like they would in winter.

So have an old refrigerator on standby. Wrap the young plants in paper or sawdust which has been dampened (not soggy!) and place them in the refrigerator for the 6-7 week period.

Seedlings and some young plants can be grown under light night and day. There is no restriction on light here.

For more details on strawberries, see my book on "How to Start on a Shoestring and Make a Profit with Hydroponics" at (http://www.mayhillpress.com/index2.html).


2. And the Lights that Might Go With Them

In an enclosed system where artificial light is employed the follow- ing criteria must be employed.

The canopy or topmost leaves get all the light. If you go down vertically you will find that past the 5th or 6th leaf the older leaves are either yellow or dying. Pinch them off and re-adjust the plant and the lighting.

Some outside but temperate air must constantly be brought in to keep the greenhouse or growing room in a "fresh" condition. Also additional carbon dioxide must be added as a supplement to aid growth and plant performance.

Relative humidity must be around 50-60% in most cases and for most plants. As a rule of thumb, check the walls and floors of the plant enclosure. There should not be water condensing on the walls or lying stagnant on the floors. A good idea is to have a ventilating fan going at all times.

Your lights (lamps) should be placed in an environment which will enable them to last a long time. Check the life and temperature needs of the lamps you buy and use them accordingly.

Don't get too fancy. Plants can do well with the ordinary florescent lamp augmented with sodium and metal halide lamps. Plants also need the radiation which can be provided by incandescent or florescent lights, provided the lamp bulbs are clear and not frosted over. Keep- ing surfaces clean, like walls and mirrors will do much to make your lighting system work at its best and to help give your plants the vigorous growth you desire.

Infrared and Ultraviolet lights are not that necessary. Plants get most of their lighting needs from light in the visible range.

As you learn and grow, you will find what plants require what light and how much at their various stages of growth. Each stage has its own requirements. But again, as with the strawberries, metal-halide during growth and high pressure sodium for flowering and fruiting. All of which can be abetted with incidental incandescent lighting.

And it always helps to get all the answers you can from your supplier. If he doesn't know what his lamps will do and for what, then who does?


3. Here and There

Coconut Fiber:

This is the newest medium (now being preferred by many over rockwool) because it has many excellent qualities. Among these are the fol- lowing: low cost, disposal not a problem like with rockwool (coconut fiber decomposes when you are through using it), has great water holding capabilities, holds its structure much longer than say other media, such as peat.

It isn't toxic and just about inert chemically. It has been recom- mended for hydroponic systems such as drain-to-waste and flood-and- drain. It has very high aeration capabilities and is best used in situations where a high retention of moisture is needed.

Coir (coconut fiber used in hydroponics) has an added advantage be- sides being able to replace any other current medium. It has very low nutrients so it won't interfere with your nutrient solution's chemical composition. Its pH is just right for most plants.

You can use it any kind of system but it's best for drain-to-waste. You won't have water logging either. Less fertilizer and less water can be used. In flood-and-drain setups, plants will stay moist between floodings. It can successfully be used to start seedlings in NFT setups. You can get it in blocks or mats. Some growers mix it with fine gravel - this allows the mixture to have more water capacity.

Buying nutrients:

Don't buy your nutrient formula already pre-mixed with water. Buy it dry and add your own water. Why? To save money on freight. Unless you are a commercial grower specializing in one or two crops, a nutrient formula which is generalized will do well for most of your plants.

Hydroponics in the open:

That's right - outside with mother nature, no greenhouse needed. If you have my book (http://www.mayhillpress.com/index2.html), you already know that I recommend starting out this way. In fact the greenhouse design included in the book stresses lifting side panels during good weather.

So why bring it up. It seems Ray Cogo (Webberville, MI) is making a career out of preaching this doctrine. He augments his fabricated designs with shade houses instead of greenhouses. And he goes about showing others how to do hydroponics outdoors and why it's such a good idea.

His design includes PVC pipe including the poles which hold up the shade houses. And he insists, because the plants are out-of-doors, that they are bug-free, especially if you add a dose or two of bene- ficial insects. The only thing you have to watch out for is the possibility of frost coming too early.

British Columbia changing its ways:

Growers here are deserting spaghetti type systems for irrigation and going back to flood floor, ebb and flood and trough systems where the nutrient is recirculated. The growers are also using rockwool for cut flowers as well as rockwool and sawdust for vegetables.

Their main reasons for this change in systems is to eliminate or re duce salt accumulation in the bottoms of the plant pots as well as cutting down the incidence of powdery mildew and botrytis.

BC growers have long used sawdust as a medium because they say it gives top quality and high yield in their crops. If you use sawdust as a medium you must avoid toxic items such as red cedar and, in some cases, pine. Also check the manganese level of the sawdust you use.

Some more tips on lettuce:

It's a cool weather crop! 75 degrees F is too hot! So use shading above them as well as some form of cooling.

If the temperature is too cool for lettuce (or any other plant), heat the nutrient solution to around 69 - 76 degrees F. This will not only save you money on heating but will also keep the root system and the rest of the plant happy. Protected immersion elements can be placed into the nutrient solution to heat the solution.

Heat from the root system will rise and warm the plant, providing you augment the air temperature with some form of heating.

Plants will be happy if you don't let the nutrient and air temperatures vary by more than 4 degrees F. Large nutrient tanks can provide a buffer against temperature extremes, especially in hot climates.


4.Milkweed Bugs

Why is this bug beneficial? It keeps milkweed from getting out of hand by sucking out the plants juices. This interesting bug (Oncopeltus fasciatus) can fight off most diseases so survives quite well so long as its host plant is around.

The adult's color is black and orange-red. The female's eggs are laid out in bunches of up to fifty eggs. The nymph will hatch out in a week at temperature of around 75 degrees F. They are fast growers, starting out the size of a pin and after five moltings achieve the adult size where they now have stubby wings. Their entire life cycle is close to a month at the above temperature range although they will live longer at cooler temperatures.

If you want to rear them, go to the nearest milkweed patch and collect both young and adult. The best time to do this is in August or September when the milkweed pods become brown. Be sure to collect a lot of the pods, separate the seed from the pods and place in a dry place for food which you will later need.

Rearing includes placing the nymph as well as the adult bugs in a container which has can be easily kept clean by having some sort of paper toweling on the bottom. Keep an a cover on the top of the container and feed with the milkweed seeds you have collected. Don't forget water - use a wick type device to furnish the mois- ture the bugs will need.

And then you and the milkweed bugs can live happily ever after.


5. Safe (Natural) Insecticides


As the Greeks said, moderation and care must be taken with all things. I, myself, don't care for the use of insecticides, but there may be times when their use is necessary.


One of the more toxic insecticides, rotenone causes death in in- sects by stopping or slowing down respiration on the cellular level. It attacks muscle and nerve cells and causes the insect to stop feeding. Death may take hours or days.

The insecticide is sold in powder form (5%) and can then be mixed for spraying. In sunlight and air, the chemical oxidizes fast. If spared on the bottom leaves, it will last for a few days. If you are spraying this chemical on vegetables which are soon to be harvested, you will need to mix it with soap in order to hasten its decomposition.

Keep rotenone runoff away from your fish pond - unless you want to kill all the fish in it.


This is one of the most popular botanical insecticides. It kills insects by stopping the potassium-sodium ion exchange in nerve fibers. This slows down nerve impulses and can result in instant paralysis.

But the insects can sometimes metabolize the chemical and recover. So it's best to buy your pyrethrum with PBO which is a synergist which the insects from metabolizing and recovering.

Pyrethrum breaks down very fast in air, moisture and sunlight. Do not mix with soap because the breakdown will be too fast to do you any good in getting rid of the bugs. The product must be used as fresh as possible because its potency decreases within a matter of months.

Pyrethrum (or Pyrethrins) are a good offense against mosquitoes, fleas, ants and roaches (to some degree), Indian meal moths, flour beetles and for many insects found in the average garden.

You may have heard of Pyrethoid insecticides. These are not botan- ical but are synthetic instead. They are, however, quite toxic to insects but remain in the environment for a longer period of time. This chemical has its uses, no doubt, but because of its slow break- down it is probably best to avoid its use.


This is a stomach poison and takes time to do its job. The insect does stop feeding. It must be used with PBO in hot weather.

Its primary use is to control codling moth, citrus thrips and the corn borer (European). It is a botanical and lasts longer than those already discussed.


Well if you thought it was bad, it's certainly bad for some insects (not all). As we already know, nicotine is chemical which is toxic to nerves; it causes uncontrolled firing of the nerves. In the insects it can kill. Nicotine works very fast, causing failure of necessary bodily functions.

The chemical is generally used as a fumigant for greenhouses in order to get rid of mites, thrips and aphids. BUT BEAR IN MIND: any nicotine mixture able to kill insects can also kill you. SO BE VERY, VERY CAREFUL.

Best not to have to use it at all. But it does have a saving grace: it decomposes within a day!


Causes death, paralysis from nerve functions being destroyed. Some insects die immediately - others live on for days in a paralysis. Do not apply it when bees are around as it will get into the honey. It degrades very fast in the presence of sun- light and air. There is no residual toxicity.

Used on a variety of vegetables, such as beans, cucumbers, melons, squash,peanuts, citrus, collard greens, mustard greens, cabbage and broccoli.

These are the main ones. Others are obtained from extracts of citrus oil, such as Linalool and Limonene. Herbal remedies also abound, such as oils from lavender, pennyroyal, cedar( for repelling moths in cedar chests), citronella (for repelling mosquitoes in the back- yard),and eucalyptus, and Neem.

Insecticidal soaps are also available. These help control insects which infect houseplants or ornamentals.

Some people try to make these sort of soaps from household chemicals. Don't do it! These chemicals can combine and become very harmful not only to you but also to your pets.

BE CAREFUL when applying all insecticides, "safe" or otherwise, especially around pets. Wear protective gear at all times. Do not let anyone go into a treated area unless you are certain the chemicals used have dissipated and are no longer a threat to you or your pets.

Incidentally, keep your pets where they belong - not in your growing areas or green houses!


bsaffell@mayhillpress.com...Last Update: 52008 copyright 1996 - 2008 by Hilmur Saffell

They are as follows:
"How to Start on a Shoestring and Make a Profit with Hydroponics"
"Big Dollars Growing Gourmet Salad Greens"
"Beneficial Insects - How to Mass Rear and Make a Profit"
If you would like a copy or copies of your own,

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