Soil crusting with direct sowing

wulfletons(Zone 7a)July 9, 2014

The ugly, stressed (but still producing) tomato plants in my garden today got me thinking about the fall garden.

I have never been very successful at starting seeds either indoors or direct sowing. I'm sure there are lots of reasons for this, but one thing I run in to when direct sowing is that I have trouble keeping my soil moist enough to keep it from cracking.

It seems like I've heard some mention of covering directly sown seeds with potting soil instead of garden soil help them germinate without having to break trough crusted soil, but I've never seen a detailed on post this. It is as simple and digging a shallow trench and then covering with potting soil to the desired depth? I would appreciate any input.


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Dawn has posted some kind of Oklahoma link that works fine for me. Just make a groove in the soil and use compost or potting soil to cover the seeds, it also shows a screen to cover the plants ( which I never had before).

I think the link is a fall gardening guide.


    Bookmark   July 9, 2014 at 9:56PM
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OSU Fall Planting Guide

Wulf, I'm doing this now. What I'm finding is we are seriously dry. The peat moss didn't help on my brocolli seeds. It dried out. Cutting a groove (or a furrow in some cases) does help keep moisture in. But we're too dry. On another thread George reminded that we can put some cardboard atop the seeded area, but we must be certain to remove it immediately following germination.

I'm like you... I'm sick to death of starting seeds indoors. I'm too slow and always too busy to keep up with gabillions of transplants. But the blazing sun dries everything out too fast if I direct seed. So, I'm going to reseed my broccoli in the groove/furrow like Larry suggested and cover it with cardboard to see if that will keep it sufficiently moist. I even sowed in a furrow in shade!

I haven't used the screen, either. I'm wondering if the screen is to provide protection from drying winds as well as birds? The guide doesn't explain.


    Bookmark   July 9, 2014 at 10:28PM
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Okiedawn OK Zone 7

Krista, I think Bon and Larry covered it all just fine. I love how we all work together to answer questions.

Now, about the peat moss. Peat moss is an odd duck, you know. When peat moss is very wet, it can stay very wet forever, but then once it dries out, it is almost impossible to re-wet it. Knowing this, I was sort of surprised that they recommended it for use in the trench, but the Fall Garden Guide likely was written in a wetter decade when mid to late-summer weather had more rainfall that what we've had in recent years. So, to use OU's recommended trench planting with peat moss, all we have to do is keep the trench and replace the peat moss with something else. There's several options....home-made compost would be preferable, if you have finished compost available. However, if your pile has been really dry and your compost is really bone dry (lots of us still are in various drought stages, so there's plenty of dryness in plenty of places), you might need to put your compost in a container of some sort and soak it down good before you add it to the trench. If you don't have compost, you could use a good-quality soil-less mix. I think that the Miracle Grow Moisture Control soil-less mix would be great for this use. Still, even it can get really dry so you need to start out with it being good and wet before you put seeds in the trench.

You also could use the pre-sprouting method where you pre-sprout seeds indoors in a coffee filter or paper towel inside a zip-lock bag and then sow the pre-sprouted seeds into the trench. Since they are pre-sprouted and you're putting them in a trench with a non-crusty soil-less mix, you ought to get little plant sprouting quickly.

The screen is for shading the soil. Do y'all remember how we go into so much detail in spring about how warm the soil needs to be for each individual vegggie's seeds to sprout? Well, guess what? The opposite is true as well. Many of the veggies we want to plant for a fall harvest will not germinate in our hot soils, not even if you use the trench and a nice moist soil-less mix when you sow seed. You sometimes have to shade the trench and the ground around it. By shading it, you can reduce the temperature of the soil surface and the soil at seed-planting depth by 20 degrees or more.

Most cool-season seeds will sprout better indoor in flats. I like to use bathroom sized cups. I think they still come in 3 oz and 5 oz cups. I tend to use 3 oz in spring and 5 oz in fall because larger cups hold more soil-less mix that won't dry out as quickly when you're hardening off seedlings in July, which is very different from hardening off seedlings in March or April. I cut the bottoms out of the cups so they are bottomless pots, line them up in a flat (I use aluminum roasting pans, as anyone who has seen my plants at the Spring Fling likely remembers) and fill them with pre-moistened soil-less mix. I sow the seeds (at least 2 per pot), put them on the light shelf and wait for the seeds to sprout. Normally, as soon as they sprout....and I mean while they are still just barely sprouted, I move them out to the front porch where they grow from day 1 in morning sun and afternoon shade, but with some protection from the plentiful supply of summertime insects that are out in the yard and garden. Once they are a week or two old and have just a couple of true leaves, you can harden them off to full sun and heat and transplant them into the garden. I like to transplant while they are fairly small because they suffer less transplant shock. Using plantable paper cups with the bottoms cut out also means less transplant shock. It doesn't have to be paper cups. It can be the cardboard tubes from toilet paper, paper towels and gift wrap. Just cut the tubes to the desired length and line them up in your flat and fill them with a moistened soil-less mix.

I tend to shade newly transplanted fall plants for the first few days. Shading is easy---a couple of lawn chairs, with one at either end of the area to be shaded, and a piece of shadecloth, an old bedsheet, etc. and you've got it done. Be sure the shade cloth is a couple of feet above the tiny plants for good air flow or they can roast beneath it if you have the shade material just a couple of inches above them.

Not only are we really dry here at this time of year, but we tend to be really, really hot and that heat is very hard on tiny young seedlings, so in a lot of ways, it can be harder to get the new plantings established in the heat and the very intense sunlight.

Of course, there are some things that are best seeded directly---like carrots, radishes and spinach, for example. My favorite way is to use a soaker hose to get the ground really wet, then sow the seeds, cover them to the appropriate depth, pat the soil down firmly, mist it lightly to help settle in the soil you just patted down and put a board on top of it. My beds are 4' wide, so I normally use scraps of plywood left over from various projects, but any sort of board would work. In the absence of wood, very thick cardboard could serve the same purpose. The wood or cardboard serves several functions--it prevents wind or rain erosion from washing away the small seeds. It shades the ground beneath it and keeps it a little cooler. It keeps small animals from digging up the seeds. It serves as a sort of mulch that helps maintain the soil moisture level. While the soil beneath the wood will dry out, it will dry out a lot more slowly. You need to lift the wood every morning and every evening to see if you see tiny green sprouts. As soon as you see them, you have to remove the board so they don't die. Once you remove it, you need to watch the soil carefully and make sure it doesn't dry out.

Then, don't forget the pests. Fresh, young, tender foliage will be very attractive to all kinds of insects, and even to thirsty little critters like field mice, birds, squirrels etc. Remember how very hot and dry everybody and everything is during the months of July and August. So, you can use the lightweight form of floating row cover to protect plants, cheesecloth, tulle netting, or sheer curtain fabric---whatever you can come up with that will keep your young seedlings safe. You also can provide a diversion for thirsty beasts and birds---a flat pan of water (aluminum pie pans work fine for this) so they can find water to drink without sucking the life out of your plants.

Once you uncover those tiny seedlings that were beneath the board or cardboard, remember that they aren't used to any sunlight so if you shade them, remember to do the hardening off routine where you remove the shade for an hour the first day, two hours the second, etc.

It is really easy to assume that a fall garden is easier for various reasons, such as having fewer pests and decreasing pest levels. That is true. However, getting plants to sprout and grow in July and August can be tricky, so we have to work a little harder at the planting and establishment stage. We usually have a lot less rain falling in mid to late-summer than in spring, but if we just spend the extra time to get the seeds germinated, the transplants planted, and keep the young plants well-protected from pests, we'll have happy, healthy plants going into autumn. Sometimes, depending on how brutal the heat is, you may notice that the plants grow pretty slowly at first, and they do, but they are having to fight the effects of the heat. As the weather cools and the autumn rains begin, the garden will thrive.

If you have a lot of trouble with birds eating seedlings, bird netting will work. Or, you can hammer stakes into the ground around the perimeter of the bed and then randomly run light-colored fishing line back and forth in a random pattern (pretend you're making a spider web). The birds won't be able to see the fishing line very well and will sort of fly right into it as they are trying to get to your plants. They'll hit it, it will spook them and they'll go away.

Got any more questions?


    Bookmark   July 9, 2014 at 11:53PM
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I totally forgot about germination temperatures. I didn't even finish reading your post. I started seeds in baggies in a nice comfy spot. Then I finished reading. Is 50 percent failure rate typical for a newbie?


    Bookmark   July 10, 2014 at 4:49AM
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Okiedawn OK Zone 7

A 50% successful seed germination rate isn't bad with broccoli. The federal germination standard for broccoli is 75% I think, so you're only guaranteed 75% of the broccoli seeds will sprout anyhow. (Though often you get well above the federal germination standard---that's just the minimum acceptable germination rate for any broccoli seed sold in this country. You still could get 100% germination.)

When you're ready to move the plants outside, watch them carefully. While cabbage loopers and imported cabbage worms are not as bad in fall, they often still are around. Often the reason they are around is that rain has been falling. If rain is falling, it stays a little cooler. If it stays a little cooler, native brassicas grow. If native brassicas grow, the pests have something to sustain them all summer. If the pests survive the summer, they're going to find your plants and lay eggs on them. I'm still seeing cabbage whites fluttering around, so there must be some native brassicas somewhere around here....probably in a pasture

Brassicas have a long life here in the fall for the most part. I usually can keep broccoli and cabbage growing forever in fall and winter.....with forever being until I stop covering them up and let them freeze, which likely happens if we drop below about 15-20 degrees. I think I had cabbage freeze at 18 degrees a couple of years ago, but that was in January and by then we had harvested cabbage for months.

When you cut off your first cabbage head, if you leave a "stump" of a couple of inches and gently slash an "X" into the stump, so that it is sort of split into 4 pieces (but the pieces have to be attached to the stump, not completely cut off), then often it will give you 4 new small cabbage heads. Each one only gets maybe tennis ball to baseball size, but that's not bad considering you already harvested the main head. It is an amazing way to get more of a harvest from your plants.

    Bookmark   July 10, 2014 at 10:28PM
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Seriously? How cool is that?!!

    Bookmark   July 11, 2014 at 7:49AM
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Okiedawn OK Zone 7

It is pretty cool. I first read about this in Jeff Cox's book "Jeff Cox's 100 Greatest Gardening Ideas", which is a great book....and was published maybe 10 or 15 years ago. The 100 projects are sorted into 4 sections---one for each season---and there's tons of useful ideas like this one. It is one of the most useful garden books I've ever read in terms of offering practical projects that anyone can do. I bet a person could get the book for next to nothing nowadays as a used book on Amazon. The shipping probably would cost more than the book.

    Bookmark   July 11, 2014 at 5:50PM
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Yeah. 1 cent and shipping. I'm getting that one.

    Bookmark   July 11, 2014 at 11:26PM
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wulfletons(Zone 7a)

Thanks everyone. I've looked at the Fall Gardening PDF at least 315 times and never even noticed the part about planting.
This weekend I will take a look at my seeds and come up with an attack plan.

And Bon, I would LOVE 50 percent germination of ANYTHING, and I have found that I can't control the worms well enough to grow any brassica crops, unfortunately

    Bookmark   July 12, 2014 at 8:34AM
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Lisa_H OK(7)

Krista..for the spring garden...check out the winter sowing method. It is hands down my most successful method for starting seeds. I have been too lazy to do it the last couple of years so I end up direct sowing which is never as successful as I would like it to be.

    Bookmark   July 12, 2014 at 11:15AM
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Okiedawn OK Zone 7


You can control the worms. It just takes consistency. You can do this. I know that you can do it because a lot of us do. Fresh brassicas are so yummy, but I hate the worms and wouldn't think it was worth growing if I had to deal with them constantly. Hand-picking and drowning them works, but it can be time-consuming.

Here's two methods:

1) The organic spray method. Spray your brassica crops with Bt 'kurstaki' regularly, following the product's label directions. When the caterpillars feed on the sprayed plant matter and ingest it, it kills them. It will take a day or two for it to kill them, but they stop feeding soon after ingesting it. It only harms caterpillars, so it is relatively low-impact. However, remember it can harm your butterfly and moth population so be sure you don't spray it on flowers they visit. I only spray the brassicas and I have them in a separate bed from plants I grow for the butterflies, including dill, parsley,fennel, milkweed, and a nice assortment of flowers so that none of the actual butterfly plants are close enough to the brassicas for Bt to drift onto them. There are many Bt products. The one I usually see in stores near me is called Thuricide.

2) If you don't like spraying anything on crops you are going to eat, you can put tulle netting on hoops that cover your brassica beds. Tulle is very inexpensive, especially when compared to agricultural netting like Proteknet.

You can make hoops by hammering rebar into the ground on either side of the row or rows of brassica and inserting PVC pipe over each piece of the rebar so that the PVC is bent into a hoop shape. When these hoops are covered with something (in different uses it could be frost blankets, greenhouse plastic, tulle netting, summerweight row cover, shade cloth, etc.), they usually are called low tunnels. You can order bolts of tulle netting online or can find it at fabric or craft stores. Put the tulle netting over the hoops and use landscape pins, boards or metal t-posts laid along the edges to hold the edges of the tulle netting down tightly to the ground so caterpillars cannot crawl under it. This may sound like a lot of work, but it really isn't. Once the hoops are in place with the tulle netting over them, you don't even have to lift it again until it is time to harvest.

An additional measure you could take would be to treat the ground where you will put the tulle netting with beneficial nematodes before you plant. The beneficial nematodes will attack various pests that live in the soil, overwinter in it or survive the winter in it as eggs or cocoons or something similar. That would eliminate the problem of having pests come up out of the ground underneath the netting after it is in place.

Once you use low tunnels to protect crops, you'll wonder how you ever lived without them. I even put low tunnels over my onions when I plant them. I use either deer netting or chicken wire as the base layer of my tunnels. I grow a lot of onions for various canning recipes as well as for fresh use, so to lose the onions to hail would be a major loss. With deer netting or chicken wire in place, my onions are safe from hail. Then if really cold weather threatens I can toss a frost blanket right over the existing low tunnels.

We can work with you, too, on seed germination. The key factors involved in getting good germination include using seeds that are fairly fresh, using a good seed-starting mix, watering properly (not too much, not too little) and having the right amount of heat. Also, some seeds need darkness to germinate, but others need light and should be surface sown. You can have great success with seed sowing once you figure out what each type of seed needs. I promise you that once you get the hang of starting from seed, you'll wonder why it once seemed so hard.


    Bookmark   July 12, 2014 at 12:02PM
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