I wrote a post recently that discussed transplanting, mainly as a way to get earlier crops in spring. Now I’m going to write about direct-sowing. This is the word for putting the seeds directly into the ground outdoors.
As with transplanting, some crops are just not going to thrive if you start too soon: cucumbers, peppers, and even tomatoes, for example. Make sure you can provide conditions that meet the minimum temperature requirements for these tender crops. See my book Sustainable Market Farming, for the details, and The Year-Round Hoophouse for a chart of germination temperatures, telling you how many days each crop will take to emerge at various temperatures. Buy a soil thermometer and push the stem all the way into the soil to measure at a depth of 4” (10 cm) I find it helpful to push the thermometer stem through a larger colorful plastic lid, or stake flag. And install it somewhere safe, where it won’t get stepped on, mowed, or tilled up.
March conditions have become more unreliable, often colder. For example, if the soil at 4” (10cm) deep is 40F (4.4C), you might do better to wait if your chosen crop will take more than 21 days. In cold wet soils, seeds can rot rather than sprout. Write down your sowing date and check the soil for emergence. If nothing has come up when it should have, consider resowing. You could rake or till the whole row or bed and start over, or you could hedge your bets and sow new rows in between the original rows. This might mean ending up with fewer rows, or rows closer to the bed edge than you like, but you will be salvaging an unfortunate situation, so it will be better than a crop failure. If the original rows do come up, you can hoe off the new rows, and it won’t have cost you that much time or money. If the original rows are patchy, hoe them off and keep the new ones.
The pros and cons of transplanting and direct sowing
Before you even venture out there to sow seeds, consider the pros and cons of transplanting versus direct sowing, and when each is most appropriate.You can read these in my post about Garden Planning
How to sow a row of seeds
Find out how deep the seeds should be: bigger seeds go deeper. If you sow too deep, down where the soil is colder, the seedlings will struggle to reach the surface and may fail. Up to three times the seed diameter, is a concept I’ve often read. Not that you need to measure it!
Drag a triangular hoe (warren hoe) or the corner of a regular hoe, along the ground where you want the plants to grow. If your line is not as straight as you like, fill it in and set out stakes and twine. Either use the shadow of the twine as your mark, or eyeball a constant distance from the twine to the hoe. Remember the depth you need. Fix any deep excavations, or superficial scratches.
Next open the resealable end of the seed packet and pour some out (not over the gum!) into a small dish or the palm of a dry hand. Keep in mind the plant spacing you are aiming for. Radishes, spinach, chard and beets can easily be seen, and sown at one per inch. Avoid the beginner mistake of tumbling many more times the seed you need in the furrow. It causes more work and weaker plants, because they grow up overcrowded, and you will have to thin them. For small seeds, aim at two or three seeds per inch. Really! It’s hard to get good at this skill, but it is well worth learning.
If you mess up, don’t pick up damp seeds and put them back in the packet. They will damage the dry seeds already in there.
Use the hoe or a rake to draw soil in over the seeds to the previous soil level, not mounded up. Next tamp the soil down over the rows, using a hoe or rake on end. This lets the seeds have good contact with damp soil, so they can get the air and water they need.
Cover with rowcover if needed, or if wanted to speed up growth. With rowcover, you will be biding time while spring warms up. The cold weather crops will not benefit from being overheated. Spinach, lettuce and Asian greens will all bolt if their environment in spring is too warm. Read about factors influencing bolting. You will probably have some warmer weather crops going in and you can move the rowcover on those rows.
Use insect netting if you need to protect your vulnerable seedlings from being gobbled up. You will need to remove the netting once flowers appear, so that the crops can get pollinated. If you have serious trouble with a particular pest, look in seed catalogs for parthenocarpic varieties, ones that set fruit without any pollination.
If it doesn’t rain, water the next day (day 2), then whenever the soil surface is dry. It is better to water deeply less often, than to water lightly each day. Light watering may simply not be enough, and will encourage the seedlings to make shallow roots, which will then die back if you don’t water often enough. Deep watering saves water, as a good depth of soil stays wet, and is protected from evaporation by the surface soil. Some people even go so far as to hoe very shallowly to create a “dust mulch” which prevents warm days wicking the moisture out of the soil. For most of use, this is more of a summer issue than a spring one.
Soaking and pre-sprouting seeds
Some larger seeds benefit from soaking before sowing. Peas and beans can be soaked overnight, but smaller seeds need less soaking. Be careful with beet seeds as they can easily drown and rot if soaked for too long.
Pre-sprouting can help with germination when soil temperatures are too cold or too hot for the crop to germinate in a timely way. In spring, if you presprout, be very careful not to overwater the soil until you see the seedlings emerging. This task is not as exacting as growing bean sprouts to eat. You don’t need to rinse them more than once every few days, if that.
To sow soaked or pre-sprouted seeds, first drain off the free water. If the wet seeds tend to clump together in your fingers, either spread the seeds out on a try or a piece of rowcover or similar, until the problem is solved (an hour?) or else mix the damp seeds with a dry, inert, organic dust, such as oat bran, or uncooked corn grits. Some people use dry sand, but if you have a lot to sow, you will find this quite abrasive to your fingers or to the plastic plate of the mechanical seeder.
If your seeds are expensive, or you don’t have many, or the germination is questionable, you can station sow, rather than sowing in a furrow (drill). Simply press a small divot in the soil at the chosen spacing and put about 3 seeds in the hole. Close the soil over the top. This works well if direct-sowing big crops like okra.
Using a push seeder
If you have long rows, you might use an EarthWay type seeder. These inexpensive push seeders are very quick and easy to use, and come with a set of relatively easily-changed plates with holes for seeds of different sizes. They are lightweight and can be used at a fast walking pace.
Market Gardeners will look longingly at the Jang Seeder, which is much more accurate at spacing seeds, and costs an undeniably much larger amount of money. At one time we kept our EarthWay just for carrot sowing (we grew a lot of carrots!), and we used a Planet Junior push seeder for other crops. These are heavy-duty seeders, with plates that are a confounded challenge to change over. In the wrong hands, or on the wrong day, the whole hopper and plate mechanism would fall off. Other people like them for their sturdiness and don’t have the problems I had.
Growers doing no-till seeding might be interested in the very heavy duty Haraka planter I wrote about last year. It is made in South Africa.
Gap-filling with transplants
A special application of direct-sowing is to prepare for incomplete rows emerging, by having some back-up transplants for gap-filling. We have often done this with our first sweet corn, in case the weather turns cold, or cold rain lands on the plot. Sweet corn can be successfully transplanted up to about 2” (5 cm) tall. We sowed ours in Styrofoam Speedling flats. In cold areas, some growers transplant their whole first planting.
Gap-filling in transplanted crops with station-sowed seeds
Another special application of direct-sowing is to fill gaps in rows of transplanted crops when you have no reserve, backup transplants. This only works for fairly fast-growing crops with long harvest periods. You will need to decide if your seeds will have time to reach harvestable size before the transplanted ones are pulled up.