Starting Seeds and Transplanting Fall Crops in Summer
Sharon July 14th, 2009
The hardest part of fall gardening for most people is getting seeds to germinate and plants to tolerate transplanting during summer conditions, so they will be ready when things stop growing in the fall. This is genuinely a tough project for a lot of us - and tougher for most people than me (given that we have yet to break 80 since May, and most of our nights feel like early September, I’m not sure that I’m going to have to do much, but this is unusual) - hot, dry weather makes it nearly impossible to get a lot of crops into the ground.
One of the first tricks to use is the same one we cold climate folks use to get our plants ready in winter - start the seeds indoors. This obviously is only true if some part of your house is cooler than the outside, but since that is the case for many of us, find the cool spot and plant your seedlings there. Up to a certain point, larger seedlings with more extensive root systems will handle transplant better, with a good, moist start. This isn’t bad advice for those of us up north, either, when dealing with particularly light sensitive plants that are prone to bolting - some of these, like many asian greens don’t transplant well, but us northerners who are often our fall crops at the height of the long days don’t want to see them bolt immediately - so growing them inside, where they get less, but sufficient light may actually give them a boost.
Another thought are shady beds, particularly under deciduous trees. One of my best garden beds is under a large white paper birch that shades our kitchen window. It is a lovely tree, with the added virtue of leafing out late and losing its leaves early - so it allows in the sun while we want it, and cools the house when we don’t. I plant greens in these shaded beds, and they do well all summer, and then as things get cooler, enjoy the burst of additional light that puts on new growth in the fall.
You can make structures out of shade cloth, or if you don’t have shade cloth, make something out of an old, threadbare sheet and some bits of wood lying around. You have to move it on and off, but the difference in temperature and light absorption can be critical.
Mulch is powerful here - not only does it help soils retain water, but it also keeps them cooler than they would be without it. Straw mulches are particuarly valuable because they reflect light back, rather than absorbing it.
Even a piece of board can make a big difference if you are germinating seed in hot weather - water deeply and cover the row of seeds with a board and check daily for germination, removing the board as soon as the seed are up.
Moisture is critical - transplants or seeds will do poorly if allowed to dry out before their root systems can reach down into deeper subsoils. Consider making trenched garden beds - instead of raising your gardens up, if your climate is warm and dry, make them in low ground, where moisture can pool. Water regularly, ideally directly at root level, particularly when seedlings are young.
Look for varieties that can take some heat as well as cold - those in warmer climates than ours may not struggle as much to overwinter greens - thus, instead of planting winter density lettuce, you might do better with thai green or marvel of four seasons, both of which have some bolt resistance built in. Several people mentioned that “ice bred” plants didn’t do well for them in their warm climate - I’d tend to expect that - if the plants get stressed early, and are bred mostly for tolerating cold, they probably won’t do well over the winter where the falls are long and warm.
This means a certain measure of experimentation - don’t assume, if you live in Oklahoma or Georgia, that what you want are the cold hardiest varieties - you may instead what something that generally does well in your area. If you have the space, do variety trials and compare - this information will be enormously valuable to your neighbors and friends nearby, and may be useful to your local cooperative extension and any local seed companies.
If you can, wait to transplant seedlings until you can expect some moisture and cooler weather. If that isn’t possible, harden your plants off, just as you would if you were planting them out in springtime in a cold climate - gradually accustom them to getting a little bit dryer, and put them out initially in a shady spot, only gradually moving up to the amount of light they’ll get.
Season extension for hot climates - that is, finding ways to extend the season through the warm, dry periods, seems to me less fully developed in gardening literature than cold season gardening. I realize that some of this information is available locally, but it seems less well dispersed - and yet, making sure that food keeps coming through the hot dry seasons when little grows is just as esssential as storing for winter. Balancing the two - timing the fall crops around the heat of summer, is a delicate balancing act.
Sharon
- cool season gardening
- Comments(7)
Thank you so much for posting all this online. I’m reading Eliot Coleman as well, so I’m hoping between two great sources-one north of me, one west, but both in the same general region-I’ll figure it out.
One challenge for me to figure out is where I’m going to put fall crops. With this cool summer, many of my early-season crops that I figured would be long gone are still going strong. Who knew the peas I planted in March would still be producing mid-July? It’s good, but I’d planned on having that space freed up by now.
Mulch is equally critical here, in the desert, to keep the soil moist and cooler during the hot, dry summer preceding the monsoons. Shade cloth helps but can’t work miracles - mostly it keeps the direct sun off the plants. The temperature inside my husband’s “shadehouse” still gets quite high on a hot day. (Yesterday, it was 112 in there until I turned on the misters which dropped the temperature a bit through evaporative cooling.)
While we may plant some new seeds for fall, it is also a time when plants from the spring experience a resurgence. It is not uncommon to get a fall crop - a second crop - of tomatoes and peppers. The problem in the summer is the high temperatures actually cook the pollen. As the temperatures ease up, plants are able to produce again.
I agree that season extension in warmer climates isn’t treated as fully as it seems to be for colder climates. I’ve had to learn from experience what works well for me here in the St. Louis, MO metro area. Even the supposedly reliable sources of such info - the state extension service and Gateway Greening, the local community garden organization - haven’t been as helpful on starting fall crops as they have been on starting spring and summer crops. There aren’t as many regional seed companies for warmer areas either, where you might expect to find seeds that could make it through winter in the open garden. Southern Exposure Seed Exchange and Baker Creek Seeds are the two whose climate most matches my own.
I think a lot of the problem with growing fall veggies comes with the heat waves we get in July and August, combined with the fast cool-down in the fall. We have to have mature crops by the end of October. The local sources will say to sow seeds in the garden in July or early August, but they don’t tell you how important it is (for me) to wait till there is a 3-5 day stretch of below average temps to do it. As for holding the harvest over winter, the main problem seems to be the highly unsettled weather combined with no snow cover (we get occasional snows but they usually melt within a week). The freeze-thaw cycles, wind, cold rain, and sleet and ice really sock it to plants. Mulches give the voles a place to live, and crops give them food to eat. I find that crop survival is much improved in cold frames. They are sheltered from the wind and precipitation, and no need for mulch so fewer voles (though I do get rabbits in them … it’s always something).
To grow seedlings that are ready to be put in the ground by August, I need to start them in mid-June. I have been successful in starting them under lights in our basement or in shade on the front porch (the front porch only works if we aren’t in the middle of a heat wave at that point). Then I have to keep the seedlings alive for several weeks, during which we usually have at least one heat wave with highs in the upper 90s to over 100, and it might last for 2 or more weeks. Temps like that set back cool-weather crops so badly that they are easy prey for insects. Plus I need to keep the seedlings on a table under the porch roof (safe from rabbits and a little cooler). Only a little space there. It’s easier to start from seeds in the garden … but only if the weather cooperates, meaning a stretch of 3-5 days (more is better) with lows in the 60s, below average for the late June-early August time frame. We might not get a stretch that long, and I have not been successful at germinating cool-crop seeds if the lows are in the 70s or higher.
All this assumes we are not in the middle of one of the aforementioned heat waves during August and September, when you need for the seedlings, however they were started, to put on a lot of growth. Years when that happens - 2007 being the latest one - mean very few fall crops. I haven’t tried shade cloth, but I don’t think it, or growing in a shady place, or mulch, or anything else you mention, will help when the average high for August is 94 and the average low is 75, as it was in August 2007. At that point, all you can do is re-sow seed thickly in September and harvest whatever thinnings and young plants you can get before the daylength and temps work together to end the growing season (early November).
On the other hand, if we get a good year (2004 and 2008 were good years), I can grow lettuces weighing 2 pounds or 6 pound bok choys in the fall. It’s up to the weather more than it is up to me.
Some years here we get several months of low rainfall over summer, generally followed by the autumn rains so it is important to have those fall/winter seedlings ready to go in once the regular rains start up again. Unfortunately around that time much of the space is still taken up with tomatoes, beans, squash, zuchini etc which will keep on producing until the first hard frost knocks them back, so I don’t want to rip them out early. By the time those beds get cleaned out it is too late to plant anything other than garlic or fava beans in them. So it is always a juggling act with the space I have available - I have given up on trying to produce much in the way of brocolli, cabbages, and cauliflour, and focus on the leafy greens like tatsoi, chard and mizuna which grow faster and take up less space, and kohl rabi. Curly leaf kale is good too - if I get it planted at the right time the plants will last a full year and grow nearly as tall as me, and provide plenty of greens for ourselves and the chickens.
The root vegetables that need to be overwintered also need to get a couple of months growth before the really cold weather starts - plant too late and they just sulk all winter and bolt at the first sign of spring.
Someday we’re going to knock down our old sheds and move the chicken house and I might actually have enough garden beds to do a proper rotation
We have frequently planted too late, trying to avoid blasts of heat than can occur right into September here. This year we’ll have a winter growhouse a la Coleman for the first time — but to raise winter-hardy plants in it from the beginning of August, instead of under the fruit trees where they’re so happy, will take a little thinking through. Our current idea is to open several burlap fifty-pound-size bags and use them as shades about two feet off the ground through August and September, then put the polyethylene on the hoops in October. Open to “No, WAIT, risa, not THAT …” suggestions meanwhile!
St strange you should post this…today. I am trying to track down the number of my local County Extension Office to ask about fall plantings. I really want to plant another crop of potatoes but have no clue if the young plants will survive the hot summer sun of August and early September. Otherwise, our growing season is still long enough for the potatoes to mature underground (I think) with proper ground cover.
Thank you -
I am going to try fall cropping for the first time this year, but I’m having some success with the hot, dry season. I’m in Memphis, TN, where the 95+ dead zone temps start in late June or early July, and can last intermittently into September (with a constant 4-6 week period in July-August, hazardously hot, high humidity, little rain). The city heat island effect is bad here.
I work with people from India, and asked them what varieties of vegetables they grow in their kind of heat. Some of these were available from Baker Creek, and I’ve been pleasantly surprised by the outcome so far. The Indian cucumbers took off growing when the weather got really hot, and produced well. Malabar Spinach grows well, too. I do water everything, so I’m not selecting for drought conditions, but I think talking to people from other (hotter) parts of the world for guidance is extremely helpful.