ASK OUR ORGANIC GARDENING EXPERTS!

May 6, 2008

If you look very closely on the undersides of the leaves, especially along the leaf veins, you will spot the culprits — green worms (see photo) that have hatched from eggs laid by white cabbage butterflies and their cousins. Beneficial insects and birds will reduce the number of worms but broccoli, cabbage and related brassicas often need some human help to fend off these fast-growing butterfly larvae. Our recent online poll shows which methods are most popular:

The Bt product is a good choice; it's made from a bacteria and it only kills the worms that eat it; it won’t harm other insects, pets or humans. Johnny’s Selected Seeds offers a brand (Dipel) as either a dust or a powder that you mix with water and spray. This "dry flowable" powder will last "indefinitely" so you won’t have to buy it fresh every year. And Peaceful Valley Farm Supply sells a nifty Solo 1-liter sprayer that has a trombone extension and adjustable nozzle so that you can get the spray onto the undersides of the leaves, where the caterpillars like to hang out. 

See also: 

• The No-spray Way to Protect Plants 
• Organic Pest Control 

April 24, 2008

Those clear plastic lids that are often sold with seed-starting trays are really not necessary. (Mostly, they are a way for stores to charge a higher price.) All they do is help keep the soil moist until the seeds sprout; after that you should remove them so that the seedlings can grow without artificially high humidity. 

Seedlings may need to be moved to bigger containers before it’s safe to set them out into the garden, but this will depend on when you started the seeds and how large your initial containers are. In general, once the plants have grown to about two times as tall as the height of their container, they should be moved to bigger containers if it will be a week or more before you can put them in the ground. But young plants are pretty sturdy and can cope with smaller-than-ideal containers for a week or two, as long as you keep them watered well. 

April 10, 2008

Short-term, yes, tire planters are OK, although the soil in black tire planters will probably get hotter than most plants would prefer. Long-term, no, because the tire rubber will slowly biodegrade and release zinc, carcinogenic PAHs (polycyclic aromatic hydrocarbons) and other toxic compounds into your soil.

Toxics from tires are an even greater concern in some recycled products, such as rubber mulch and artificial turf, that are made from shredded or pelletized old tires. Here is an excellent report about the hazards of recycled tires, by Sarah Lane at Progressive Kid.

March 27, 2008

Dear Zack,

As you know, organic gardeners’ first line of defense against pests is good planning and careful observation.  Sometimes, though, that isn’t enough and more aggressive action is needed. Fortunately, there are a lot of 100-percent organic solutions available to organic gardeners and farmers.  There are more and more garden companies that offer these solutions.  Here are two that I know and like:

Fedco Organic Supply Company 

March 13, 2008

Asian ladybeetles (Harmonia axyridis) are an exotic species from China, but they are also mighty beneficials. Each day, a single adult can eat up to 270 aphids or other small insects that could damage your garden plants, and each larva will devour 600 to 1200 aphids during its 12- to 14-day feeding period. Some of that bug-nabbing will happen in your garden, but most of the action takes place in the treetops.

Light-colored buildings near wooded areas attract the attention of thousands of Asian ladybeetles in fall, and the only way to keep them out is to seal all open crevices and keep south-facing doors and windows tightly closed when they are swarming.

March 12, 2008

Seeds saved from a hybrid variety can be saved and replanted, but they won’t “grow true” to the original parent plant. 

Hybrids are a cross between two purebred lines. For example, a plant breeder might cross one variety of squash having good color with another having good taste with the goal of creating a second generation plant having both desirable traits. Seeds saved from a first generation hybrid (F1) and replanted will produce a second generation hybrid (F2) which lacks the vigor of its parent and may show some of the undesirable characteristics of the two pure varieties crossed to produce that parent. 

You can start seeds indoors in a bright south-facing window, but your seedlings will grow better under fluorescent lights. Your best bet is to buy an inexpensive 2-tube shop light at a hardware or home store. You can prop the light up on bricks on a table or the floor, and put two flats of seedlings under it. Keep the seedlings very close to the tubes — almost touching is best.

If you are getting spring fever, starting seeds indoors is a great antidote. Good choices for starting seeds indoors are tomatoes, peppers and basil. All do well in the warm, low-light indoor conditions (fluorescents lights are always far less intense than outdoor sunlight).

In order to save seeds from cucumbers, you must let them thoroughly ripen on the vine. They will enlarge and turn yellow. They should stay on the vines until the vines are dead. Bring the cucumbers into the house and let them ripen further on a dry shelf in the pantry (or someplace out of direct sunlight). When the cucumbers begin to turn soft, scoop out the seed mass and put it into a large jar of water.  Let the seeds ferment for five days, thenseparate the scum from the good seeds that have sunken to the bottom. Rinse the seeds in a colander, then dry hem on screens for at least three weeks, or until the seed snaps when bent in half. Store the seed in airtight containers, label and date clearly. Store the containers in a cool, dark place free of humidity. Seed processed properly will remain good for at least eight to 10 years.