Welcome back to Beyond Broccoil! Read parts one and two to get caught up. We’ve put our plants into the garden in the cooler weather of spring or fall, and now we need to get them successfully to harvest.

Brassica crops aren’t subject to many disease issues, though (as discussed in the last post) they can be affected by temperature extremes and variations. The biggest problems you’re likely to have, though, are pests. Animals such as rabbits, groundhogs and deer love chomping on cabbage family plants, so you’ll need to exclude them with a fence. These are not plants you want to spray repellents on—after all, you’d be eating the leaves or other parts you covered with hot pepper or rotten egg concoctions. Row covers (discussed below) may be enough to keep browsing animals out, but make sure they’re tightly secured.

Many insects also love to feed on brassica plants. Here’s a list of the most common with links to HGIC pages covering them:

• Whiteflies 
• Flea beetles 
• Imported cabbageworm 
• Cabbage looper 
• Harlequin bug 

The simplest way to deal with these pests really is to exclude them using floating row cover. I have talked to many, many gardeners who resisted doing this, thinking it was too much trouble, and then realized that picking caterpillars by the dozen off their hole-riddled harvest was actually a lot more difficult. (Worse: realizing you didn’t actually pick all the caterpillars off before cooking the vegetables.)

Read the page linked above to learn all about the uses of row covers and the different types available. I recommend trying the more durable insect mesh netting for summer crops, and also the heavier weights of row cover if you want to start your plants early in the spring or keep them going into late fall or winter. Brassicas overwinter quite well if given some protection from cold snaps. You could also consider wintering over plants in low tunnels with clear plastic or under cold frames, but remember that you may have to vent them on warmer winter days (which we’re dealing with a lot more often). Also look into shade cloth as a way to cool the soil when you’re transplanting fall seedlings in hot summer weather.

The one circumstance where row cover is not appropriate is when you’re incorporating brassicas into a flower bed as part of edible landscaping. This is great in theory, since some of these plants are really attractive. Just keep possible pest issues in mind. Surrounding brassicas with flowers will help attract beneficial predatory insects, and strong-smelling plants like herbs or members of the onion family may keep animals away. Insects might also be confused by a diverse mix of plants. But unless you’re very lucky you’ll probably have to accept some damage.

Other methods to deal with insect pests include:

• Pesticides. You can read about these at the links for each pest, above. Try to stick with organic pesticides, and use them as a last resort and according to directions.
• Handpicking. Have a bucket of soapy water handy and drop the pests in, or squish them.
• Last-minute kitchen intervention. Soak the vegetables in a sink full of water with salt added. Pests should float to the top.
• Trap crop. Plant a crop early in the season and destroy the insects that visit it. This may at least cut down on the total number of pests.
• Weed regularly. Insects feed on weeds as well as crops, so keep their food supply low.

Aside from dealing with pests, growing brassicas is not difficult. Water as needed, and incorporate a slow-release nitrogen fertilizer into the soil. Brassicas prefer a pH of 6-7.5. Add compost to your soil on a regular basis to help maintain nutrients and improve drainage. If you have room in your garden for crop rotation, it’s a good idea to move members of different families to new areas each year. Brassicas might leave a few of their insect pests behind this way (it won’t help with the ones that fly around freely) and they will appreciate the nitrogen left behind by bean family plants (including cover crops).

Pay attention to the weather forecast. If temperatures are heading upwards, your brassica plants may react by going to flower. It might be time to harvest even if the vegetables in your garden don’t look exactly as expected. I have harvested a lot of disappointingly runty broccoli heads, but I’ve also learned that small is better than exploding into bloom. (Though you can eat the flowers.)

Next time we’ll start learning about specific plants within this genus.

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.