Following our March story on row covers, several readers asked about the biggest weakness of row covers as a pest protection method, which is this: When the covers are removed to admit pollinators, pests like cucumber beetles and squash vine borers have free access to the plants.

Maybe there’s a better way. After reading about an ongoing study in Pennsylvania in which reared bumblebees are being used as pollinators for squash being grown beneath row covers, I decided to try a similar strategy. When a planting of ‘Boston Pickler’ cucumbers (grown under cover to exclude cucumber beetles) began blooming heavily, I went out in the cool of the morning, caught a bumblebee in a jar, and released it beneath the row cover.

The bee disappeared for a day, but the next day there he was, working away at the cucumber blossoms. That evening, I opened the cover and let him go. He had earned his freedom.

Four days later I was picking cucumbers, so I repeated the experiment with another bumbler and a pair of honeybees. I soon learned that when free-foraging bees are taken captive on a warm, sunny day, they lose all interest in blossoms and spend their energy fighting the row cover instead; there are stories of dead bees littering the ground when healthy hives are placed inside greenhouses. Adding a shade cover (a lightweight cloth spread over the row cover) goes a long way toward helping pollinators focus on the job at hand. I’ve also observed that bumblebees adapt much better to temporary detainment than honeybees. 

If you decide to try this technique, let us know how it goes! Please post a comment below.

The earliest fruits from these ‘Boston Pickler’ cucumbers were pollinated by bees released beneath a floating row cover:

Related reading:

* Using row covers to manage cucumber family pests is covered in recent articles on cucumbers, cantaloupes and winter squash.

* Learn more about different kinds of bees in Protect Your Pollinators.

Photo by  Barbara Pleasant  

To determine your optimum dates for sowing fall crops, add three weeks to the days to maturity ratings listed below or shown on your seed packs to compensate for days that are getting shorter. Then count back from your average first fall frost date to find the date you should sow each crop. (To find your average first fall frost date, search by state in the tables provided by the National Climatic Data Center.) Cool-season plants will continue to grow a little after nights turn chilly, but they will make most of their new growth early on, while the weather is still warm.

Many of the best crops of fall — including salad greens and various cabbage cousins — will refuse to germinate in soil warmer than 85 degrees, so the seeds are best started indoors (on a 90-degree day, surface soil temperatures may actually be 110 degrees or more). The procedure for growing seedlings is the same as in spring (see Seed Starting Basics), but care for transplanted seedlings requires some extra hardware. Insect pressure in late summer is severe, so use homemade or purchased lightweight row covers to exclude critters. (See The No-Spray Way to Protect Plants) It helps to shade each seedling with a light-colored flowerpot, pail or other cover for two to three days after transplanting. Protected from scorching sun, the seedlings can concentrate on growing reliable roots.

Cabbage and broccoli seedlings need to be planted at least eight weeks before the first fall frost, and as long as their roots are kept moist, they seem to benefit from a spell of hot weather as late summer days become shorter. When set out so late that they miss the last warm spells, cabbage cousins tend to stop growing too soon. Whether you’re working with seedlings you grew yourself or bought at a store, get them in the ground as soon as you can.

This kohlrabi plant growing in the pathway seen here was sown (accidentally) at the same time as those in the row beside it. It is stunted compared to those in the row because the soil in the path is very compacted — demonstrating the benefits of maintaining permanent beds and paths in your garden.

Photo by Cheryl Long

 
Do you have a tip you’d like to share with the Mother Earth News audience? Write it up, send it in, and you could win a free deluxe garden trowel! Just e-mail your tip to letters@MotherEarthNews.com with the subject line "Trowels for Tips" (and please include your mailing address).

If we publish your gardening tip here, we’ll send you this lightweight, ergonomically designed Natural Radius Grip (NRG) garden trowel. Its innovative design allows you to use maximum power with minimum strain on your muscles. Learn more about the trowel here.

Is it too hot now to grow spinach where you live? You may know that there are a couple varieties of spinach that can withstand high temperatures, but there are also several other excellent greens that can easily take the place of spinach in your garden and in your diet. Try growing one of these nine tasty and nutritious varieties this summer.

*These plants can become weedy, so maintain tight control on reseeding. Grow responsibly!

To learn more about growing spinach, browse our archive here. And if you have any favorite hot weather greens of your own, please use the comments section below to tell us about them.

Raised or sunken, edged or plain, logs or lumber or bricks or whatever — if you are proud of your garden’s permanent beds, please pull those weeds and take some photos to post at our free photo-sharing site! (First-timers to our photo site may want to visit the Help Page.)

New to the idea of permanent garden beds? Read this classic written by our editor in chief, Cheryl Long: Build Permanent Beds & Paths.

Photo: David Cavagnaro

Several seasons back, Jeff McCormack, Ph.D., founder of Garden Medicinals and Culinaries and Southern Exposure Seed Exchange, shared a tomato pruning method with me that delays the onset of early blight, and reduces the number of leaves lost in the course of the season.

Extension publications often suggest pruning tomatoes to prevent disease by improving air and light penetration. Jeff's method concentrates pruning at the base of the plant by removing leaves that eventually will be lost to early blight anyway. When the lowest leaves are removed just as the first leaf spots appear, you also remove millions of spores. And, because the bases of pruned plants dry quickly, the spread of the disease is slowed because early blight fungi need damp leaves in order to germinate and grow.

What's Early Blight?

The most common leaf-spot disease of tomato, early blight (Alternaria solani) fungi cause leaf spots to form on tomato leaves. Inside irregularly-shaped dry patches (which often have yellow margins), look for small dark rings. These are the fruiting colonies.  The grayish powder inside the dark rings are the spores, which splash or blow onto new leaves to form new spots. When spots become numerous, entire leaves wither to brown.

Commercially-grown tomatoes are often sprayed weekly with fungicides to suppress early blight. Organic growers sometimes use copper fungicides, which are often effective, but frequent use may harm earthworms. A few resistant varieties have been developed, but some failed to perform well in field trials, and others fall short in terms of flavor and texture.

Preventive Pruning

With big indeterminate varieties, prune or nip out all leaves that hang within 1 foot of the ground. If you see numerous lesions on the pruned leaves, you can go higher, to 18 inches. See the before and after photos below.

With stocky indeterminate varieties, trim out most of the leaves that touch the ground, but don't get carried away. If the plants have already set a heavy load of fruit, I also trim off some of the newest blossom clusters to keep the fruit:leaf ratio high. See the before and after photos below.

In addition to pruning, drip irrigation discourages early blight because the plants can be watered without wetting the leaves. Mulch after the plants are pruned to retain soil moisture.

Early blight starts with a few small lesions, but quickly spreads in damp summer weather. Eventually, the lower halves of infected plants wither to brown.

Before: Vigorous indeterminate tomatoes usually begin to show early blight symptoms just as they load up with green fruits.

After: Pruning off low leaves eliminates the damp environment early blight needs to spread, which reduces the number of leaves lost later in the season.

Before: Stocky determinate varieties that grow close to the ground are often hit hard by early blight just as the fruits begin to ripen.

After: When pruning determinates, take only the leaves that touch the ground. You can also prune off a few blossom clusters to help keep the leaf:fruit ratio high, which insures good flavor.

— Photos by Barbara Pleasant