Walls of water, potatoes, zucchini & row covers

Q: What are walls of water?

A: They are 18-inch plastic cylinders which act like miniature greenhouses. The wall forms a circle of water-filled tubes. Walls of water can be purchased at a hardware or garden supply store or online. With reasonable care they last for many years.

Walls of water let you plant tomatoes, for instance, four weeks early-not longer than that, because the plant would grow out the top. Inside the wall, temperatures stay above freezing, even when outside temperatures are in the teens, and even when the water in the wall freezes.

The hardest thing about using walls of water is filling them. I like to plant the tomato in the ground, cover it with an upside-down five-gallon bucket, and set the unfilled wall around the bucket. Once all the tubes are filled, I pull the bucket up and out.

One final word: if I level the soil very carefully where the wall is to go, it will not fall over, even in the wind.

Q: Is it okay to use my own potatoes to plant the next crop? They were grown from certified seed.

A: I would not take the chance. The original potatoes would not be carrying a disease, but they could have been slightly infected during the growing season in your garden. After a second year, the infection would be rampant. Seed potatoes cost very little compared to the value of a year's crop and there are so many serious potato diseases. I think that it is important that seed potatoes always come from different soil than where you will grow them.

Q: How can I get rid of scab?

A: Unfortunately, you can't. Scab lives in the soil for many, many years before it dies out. The good news is that it is not widespread in any garden, and scab stays alive only if it has potatoes to feed on. I am careful to move the location of my potatoes every year. I do not move them far, but I do not plant them in the original place for three years. I also hedge my bets by buying seed potatoes of a variety that is scab resistant. The label will say that they are.

Q: Last year the first zucchini growing on my plants rotted while they were still tiny, although later ones were fine. How can I prevent that this summer?

A: It is easy to prevent baby squash from rotting if you know the cause: the blossoms were not pollinated. The problem may solve itself. Sometimes squash begin to flower before there are very many bees to notice as they fly by. That most often happens if there are cool and rainy days when bees stay home. As soon as bees come through your garden, they will see those big yellow flowers and do their job.

Squash make separate male and female flowers. Bees have to fly first to a male flower to pick up pollen, then to a female flower to drop it off. Sometimes squash plants get it backwards and open female flowers before they have created any male ones.

If immature squash continue to rot, you may have a shortage of bees. You can do the pollinating yourself. Using either a cotton swab or an artist's paintbrush, pick up some yellow pollen from a male flower. (It has a bare stem.) Smear the pollen in the center of a female flower. (It has a tiny squash below the flower base.) The squash will grow normally. Check for new flowers opening every day and continue being their pollinator until the bees take over.

Q: Why can't I use plastic as a row cover?

A: There are two good reasons: unless the plastic has plenty of ventilation holes, plants underneath will get no water, and on a sunny day they will be hot enough to be cooked.

Hackett welcomes reader questions related to gardening, pest management, plants, soils and anything in between. Submit questions to mhackett@centric.net, call 406-961-4614 or mail questions to 1384 Meridian Road, Victor, MT 59875.