Montgomery College, Germantown; I think you can still register for it if you want to, as well as for the excellent classes continuing the Suburban Gardener series, on container gardening and extending the season). Among the many other topics I'm trying to squeeze into two and a half hours, I will cover (and do a little exercise on) succession planting.
Succession planting is the art of planning the garden so as to use all or most of your space in all the growing seasons. Put in a crop in spring, replace it with another in summer and with yet another in fall (and into winter, if you're persistent). The other technique sometimes called succession planting is sowing, say, a row or a few plants of lettuce in mid-March, following that with another row or plants in early April, then more two weeks later, until you run out of lettuce-growing weather. I prefer to call that staggered planting, but it's on the same principle: don't waste space or time.
All excellent advice, and I am all for it, and I try to do it and frequently succeed. However, obstacles often get in the way of my success at succession. Here are some of them:
Plants That Don't Want To Live. Since I start a lot of my own transplants from seed, along with doing direct sowing in the garden, I'm sometimes faced with the problem of seeds that don't germinate in time to get with the succession program. If I have to do a second sowing at the point when I finally give up on those first seeds, my plants will be smaller and not produce as much when they reach their Day of Doom (which is either the day I must put the next lot of plants in the same space, or the day the spring plants bolt into flower). This can also be a problem when summer crops keel over from disease or pest damage, and it's too early to sow fall crops and too late to plant more summer ones.
Plants That Don't Want To Die. The flip side of this is those plants that don't bolt, don't fade away, and keep growing and producing like crazy when they should have the courtesy to die already and make way for their successors. The lettuce in the above photo? Still edible in July. What was I supposed to do?
All right, that's enough problems. Solutions. Planning will only get you so far: no garden plan survives contact with the vagaries of nature. You can stare at GE007 all you want and it will not make it precisely true in every year (though it's a good place to start). In most years, you will need to make a plan and then improvise when some parts of it fail. Here are some ways you can improvise and/or plan around.
Stagger planting. As mentioned above, sowing a bit of your seed every couple of weeks instead of trusting it to the ground all at once is a great idea. If the first lot fails, you've already planned to do another sowing, and you'll likely get some of your crop in time to pull it out and start over - or, if you're really good at planning, you meant all along to stagger your summer crops too. Even if you didn't, you can say you did.
Just go buy transplants already. Sometimes we have to swallow our seed-starting pride and give in to the garden centers.
Overcome your nurturing instincts. To make the garden work the way you want it to, you may have to be vicious and just rip the plants out when it's time. Don't forget that crops are often edible before they look like what you'd buy in a grocery store. Baby vegetables are trendy! Also, if your broccoli didn't head up or your kohlrabis didn't get fat, you can still eat the leaves. They are the same thing as collards.
Have your lettuce and your beans, too. Lettuce not done by the time you need to put that June planting of beans in? If you have spaced your lettuce plants sufficiently well apart, either in rows or in a tidy pattern of hexagons or squares, you have room in between; sow your bean seeds there. Pull out the lettuce (carefully) as it gives up - or, possibly, it will hang on longer now that it has bean plants to shade it. If you didn't leave room in between, then pull some of the lettuce out and plant the beans where you've made space. This is intensive planting and you will have to fertilize and water more to accommodate it.
Always have a pinch-hitter ready. This is antithetical to the "but I don't wanna start plants in the summer" whine above, but actually it's fun to get a few quick-growing seedlings going in July so you can stick them in when something kills another plant. Bush beans grow very quickly. Cucumbers and summer squash are a little slower to produce but can still do the job. Swiss chard is another possibility. Caution: if like me you can't bear to throw a healthy seedling out, you may end up growing these in pots somewhere in a spare bit of sun, if for once nothing in the garden dies on you.
Yes, you do have to start the fall transplants in the summer. Or, you can buy them in September. You can even buy lettuce and spinach transplants if you want.
Shade and water. Are the secrets to getting cool-weather plants to germinate in the heat. Use the shady areas of your vegetable garden (don't tell me I'm the only one who has these) or set up a shade cloth... and keep the seed bed moist. You can try starting seeds in the shade of other plants (my problem with fall gardening is I forget to leave room for it) but remember that your tomatoes and pole beans have very thirsty roots and you'll need to water even more to get the seeds to germinate.
Our GIEI video "The Sweet Smell of Succession" can be found here.