Q. I have been trying to grow Brussels sprouts the past two years. I start from seed and each year, the plants do well; they get big and healthy and strong, but the sprouts are loose-leafed and/or very small. I garden in sunny raised beds, feed the plants with my own compost and a fish and seaweed fertilizer, and test my soil every year for pH and fertilizer needs. Should I even bother trying again? Thanks for your help; I don't know how I'd make it without your show!
- ---Janice in Hannibal, MO (zone 5b with hot and humid summers)
A. Darn! Your nice compliment at the end there trumps my natural impulse to say that we don't help people grow foods that require an equal amount of melted butter to induce human consumption. And we do need new topics for the A to Z archives, so I guess it's off to Brussels we shall sprout. Just don't expect to see any lima beans tips here any time soon!
The variety "Prince Marvel" shows up repeatedly as a BS of choice for tightly wrapped sprouts in the issues of ORGANIC GARDENING magazine I edited during the 1990s, It was even named a 'best variety for the zone 5 region' by a pair of testers (Rick and Sharon Carpenter) who gardened just an hour West of you in Macon, Missouri! (There are also a number of newer varieties available with "Marvel" in their name that should be just as good, if not better.)
The name "Long Island Improved" also shows up on a lot of BS lover's lists. And Andrea Ray Chandler of Kansas, who also tested crops for us in Zone 5 back in the 90s, praised a variety named "Rubine" for its beautiful red-colored leaves and sprouts. (Which, she explained, made the cabbage worms and other green caterpillars easier to see and squish.)
No matter the variety, the basic trick to growing great BS is to time the plants so that they don't begin setting their little cabbages until cool weather arrives in the Fall. If the sprouts start to form while it's still hot, you'll get those small, loose-leafed ones. (They won't taste very good either, which implies that my lack of love for this vegetable might be due to my not getting to eat ones that grew up in chilly times.)
BS is a long-season crop; it typically takes at least 90 days from transplant of six week old starts for the first little cabbages to start forming. Red Rubine takes 120 days; and it's not unusual to see varieties with even longer days to maturity—and many experts feel that the varieties that take the longest also produce the biggest, tightest sprouts.
But that long timing is fine, even in a short-season location, because these plants are the ultimate cold-weather lovers. Frost doesn't kill (or even remotely bother) the plants, and the little cabbages always taste sweetest when they're picked after the weather goes North. (BS lovers say that the sprouts have to sit through freezing cold nights on the plant to really taste their best.)
The fact that your starts have been good-looking and strong shows that you're raising them right; and it sounds like your soil has the natural richness these plants crave, so improving your timing may be all that's necessary. Time your starts so that the grown plants will hit the days to maturity listed on the seed packet right around the time your average daytime temperatures typically fall to around 65° F. These things are the opposite of tomatoes and peppers—you want the plants to start forming their edibles just as your main crops of summer are winding down.
So if, like me, you start your tamatas and other summer crops in early March for transplanting out in mid to late May, you'd start a "90 days to maturity" BS baby in May (June in warmer climes than Zone 5) and transplant them out around the end of June or early July. That would have them forming their first heads in late September, which would be close to perfect.
Keep the young plants cool in the heat of the summer with liberal watering and a soil-cooling mulch of shredded leaves or straw. Then, when the weather starts to chill, look for the first sprouts to begin forming down towards the bottom of the plant. (The little cabbages always appear down low and then progress up the plant.) They should be bigger and tighter now that they're heading up in cool weather.
Pull off the leaves nearest the spouts as you pick to encourage the fast growth of big new sprouts. Don't worry if the first ones are a little small and loose-leafed; pick them promptly, de-leaf the plant as you go and they should get tighter and bigger as the harvest progresses up the plant and the weather gets progressively cooler.
Don't worry about frost. And then don't worry about hard freezes. The sprouts that form after your first hard freeze should be the best tasting of all, and you should be able to keep picking through at least December.
After that, a lot of people will gently and slowly rock and push the plant until it's almost out of the ground (wetting the soil may make this easier to do), lay it down on its side, cover it with a light mulch and continue harvesting through the winter and early Spring. (When the weather finally does get hot again, rip that plant out of the ground; it's done.)
Some gardeners, however, prefer to 'top' their plants to get a big, uniform harvest. To do so, wait until the sprouts at the bottom of the plant are half to three-quarters of an inch in diameter and then break off the very top of the stalk. The plant will stop growing and direct all of its energy into producing a final run of big, well-shaped sprouts.