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Giving Your Garden Soil (and You) the Spring Treatment

A lot of my cool season seedling packets tell me to “Plant as soon as the soil can be worked in spring” without any further instruction.

Obviously, I’m not going to dig in frozen or snow-covered ground. But otherwise, as soon as it’s thawed, is it good to go?

Definitely not, according to the garden resources I checked. Soil that is too wet from melting snow and spring rains will compact easily when you walk on it. Dig into it with all of the energy of a New Englander who’s been cooped up all winter and your soil will break up into an uneven mess of clumps and air pockets.

Compacted soil. Clumpy soil. They don’t even sound good, and in fact, both are bad environments for your seedlings and transplants. Ideally, your soil should contain about 50% open pore space–that’s 25% water and 25% air. Luckily, no one is expecting you to measure the pore space; I’m only mentioning it to help demonstrate what can happen if you mess too much with your soil structure. Working your soil, especially when it’s too wet will alter the pore spaces, affecting water and air movement and how well all of the seeds you planted will develop roots and emerge as seedlings.

What’s the right moisture level for working the soil? Information on Rodale’s website suggests that if you can squeeze your soil into a ball that can be easily shattered by pressing into it with your finger or dropping it from a height of three feet, you should be okay. On April 1 of this year, I felt okay about prepping my bed at Perkins Park; the next day when it snowed was a different condition altogether. The point is, conditions can change from day-to-day.

Let’s say your garden’s moisture level is ideal for prepping it for planting. Time to get out pexels-photo-296230.jpegthe shovels and pitchforks and hoes and rototillers? Hold on…the more I’ve been reading and learning about soil, the more convinced I am that the less you work your soil, the better. Here is one case where laziness–no more back-breaking double digging–might be better for the long-term health of your garden.

Tom Akin, agronomist and State Resource Conservationist at the USDA’s Natural Resources Conservation Service in Amherst, MA promotes a minimal tillage approach to growing. I heard Mr. Akin speak last fall at an Urban Gardening course I was taking through the Trustees. Tillage alters your soil structure even under ideal moisture conditions– not just on top, where you’re digging, but deeper below, too. Soil that’s been heavily tilled tends to have compacted layers below the depth of the tilled space.

Also, disturbing the soil brings dormant weed seeds to the top where they’ll germinate and compete with your garden plants until you pull them out. AND, the more you dig around in the soil, the more you disrupt all of the beneficial living organisms in your soil–not just the obvious ones like earthworms, but also bacteria and fungi.

Now, having said all of that, some crops with fine seeds grow better in soil that’s been more finely loosened. Carrots and lettuce, for example, benefit from a fine bed. Hand-tilling is better. Do the least amount of digging necessary.

Bottom line, what’s the best spring treatment for your soil and you?

  1. Be kind to the pores in your soil. Check your soil’s moisture before you do anything in your garden. Hold off if it’s too wet, no matter how much you want to get in there. Organize the tools in the shed instead.
  2. Give the back-breaking, labor-intensive approach to garden bed prep a rest. Think less CrossFit and more meditation, if you like. Dig only as necessary.
  3. Consider getting your soil tested if you’re new to a space or haven’t had it done in a few years.

Indoor Seed-Starting Tips Part I

There’s a lot of information out there about starting seeds indoors. While there are definitely better ways to grow seeds, a certain amount of fudging is acceptable. Here in our house, we’ve had our share of seedlings that came home in Dixie cups from elementary school and fared just fine.

Still, if you want to boost your success and the health of your plants, take a look at these tips I cherry-picked from gardening resources. By growing seeds, you’ll have a greater selection of varieties from which to choose.

1) Use clean, well-draining containers, such as recycled cell packs from last season. Soak IMG_20180224_110315670.jpgthem in a 10% bleach solution for 10 minutes.

2) Don’t use garden soil: it’s not sterile, it’s too dense for tender seedlings, and won’t drain well.

This seed-starting mix with peat as its main ingredient is relatively cheap (around $5), OMRI-listed, and easy to find at Home Depot.

Personally I don’t like the little peat discs that puff up when soaked in water because it’s too difficult to control their moisture  content and they usually end up quite wet.

You want to moisten your soil until it’s damp and holds together, not drench it until it’s dripping.

3) About those seeds

  • You do not have to select organic seeds to grow organically. Choose them if you don’t mind spending a little extra money to support organic production of seeds. Usually you will find a wider selection of non-organic varieties.
  • Follow the directions on the seed package with regard to how deep to plant the seeds.  Some seeds need light to germinate and should simply be gently pressed onto the top of the soil; others need to be planted deeper. I learned the hard way that cilantro likes to be tucked in deep for darkness.
  • Plant 2-3 seeds per cell (or whatever kind of container you’re using). After they sprout, choose the best seedling in each cell and clip the rest. (Don’t pull out the extras to avoid disrupting roots.)
  • If you’re carrying seeds over from last year’s stash, expect a lower germination rate. I’ve heard that carrot and onion seeds in particular don’t keep well beyond one year and should be tossed.
  • For some crops, direct-sowing in the garden is better, either because they don’t transplant well or they grow quickly (and often early) enough that you don’t need to start them indoors. These include: beans, beets, carrots, cucumbers, peas, radishes, salad greens, squash, sweet corn, and turnips.

4) Seeds like a little bit of warmth to germinate. Some people use seed-starting warming mats. I don’t, but I do try to find them a nice warm spot in my drafty house.

5) Keep them moist, too. If you stick them in a bag like this, they should be all set for a IMG_20180224_114143841.jpgfew days. Just don’t put a bag like this in the sun or you’ll fry the little buggers.

6) But once they’ve sprouted, they like cooler temps in the 60s. Get them under the lights and take them out of plastic right away.

If your seedlings start to get tall and spindly, they might be too warm or not have enough light.

Sixteen hours is best, which is why I did invest in a grow light.

Prop them up so they’re right under the light, about 3 or 4 inches away. Keep adjusting them so that as they grow, the leaves do not touch the light.

Here’s another trick to try: cover sheets of cardboard with aluminum foil and position them to reflect light from a window, etc. back onto your plants.

7) And finally, if all of this sounds like too much of a bother, skip it all and watch for the great plant sales we have in our area. More details to follow.

Playing the Odds with Frost Dates

Here in Massachusetts, I’ve often gone by the rough guideline of waiting until Memorial Day weekend to put out all but my cold-tolerant plants. It’s not a terrible guideline, but the date of Memorial Day does vary from year to year, from as early as May 25 to as late as May 31. It’s also too late for certain cool weather crops and can unnecessarily cut short your garden’s growing season.

Official frost dates are often given as a single number, such as this date given on the Old Farmer’s Almanac website.

farmers alm frost date

Here, the frost date is listed as April 16, which is quite a difference from the Memorial Day guideline.

A few things can be noted about this chart. (1) It uses weather data from South Weymouth. How close is Braintree’s weather data to South Weymouth? I don’t know, but I’d guess it’s a better comparison than Boston, which is in a slightly warmer growing zone. And (2) spring frost dates given as a single number are generally dates at which there is still a 50% chance of a later spring frost.

How lucky are you feeling at 50-50 odds?

I’d definitely feel okay about putting out kale at this time, which says nothing about my feelings toward kale. (It’s all right.) Kale can take the cold weather.

For a better sense of frost dates, I like this chart from garden.org. (Click here to see the full chart; excerpt is below.)

Temp (in Deg F) 10% 50% 90%
Last 16 Mar 25 Mar 10 Feb 24
Last 20 Mar 31 Mar 19 Mar 8
Last 24 Apr 12 Mar 30 Mar 17
Last 28 Apr 27 Apr 15 Apr 4
Last 32 May 15 Apr 30 Apr 16
Last 36 May 25 May 13 May 1

According to this chart, there’s only a 10% risk that temperatures will drop below 32 degrees F after May 15. Now we’re getting closer to my old rule of thumb. But note that there’s still a 10% risk of 36 degree weather after May 25, which could set back members of the nightshade family (e.g., tomatoes, potatoes, eggplant, peppers) for the rest of the summer. (Side Note: The chart at Garden.com seems to suggest that frost forms at 36 degrees. Not true, but for various reasons, your garden may experience colder temperatures than those measured at weather stations. Using the dates associated with 36 degrees gives you a little bit of insulation from frost.)

Click here if you’d like to see another chart, but don’t get too bogged down in the numbers. We’re looking for guidelines based on data, not one proven date.

Bottom line? “Frost date” is better expressed as a range of dates and probabilities.

Also think about…

  • How cold-tolerant your plants are.
  • How much risk you can handle and how sad you would feel if you froze that one special tomato plant variety you can’t get anywhere else.
  • How willing you are to take some extra measures to protect your plants if a frost bogey threatens crops in late spring/early fall.
  • How long you can hold your young plants in their containers. They’ll take some time to recover if they start to get pot bound before you put them out, which is another kind of risk.

Start Here: Basic Organic Practices

(1) Build healthy soilwhich yields strong plants that are less prone to disease and pests.

  • Many of the practices noted below will help protect and develop soil. Think of it as a top priority.
  • Get your soil tested when planting a new garden and every few years thereafter.  Fall is the best time for testing–to allow time to adjust the soil’s pH if necessary–but spring is okay, too.
    • Here’s the link to UMassAmherst’s soil-testing lab. Cost is $15. Be sure to follow their instructions for soil sampling carefully.
    • The soil at PPCG was tested for metals such as lead before we established our gardens.

(2) Avoid agricultural chemicals. No syntheticOMRI

  • fertilizers,
  • pesticides,
  • or herbicides.
  • When in doubt about a product, look for an OMRI rating on the packaging, like the one pictured here.

(3) Use natural materials instead, such as:

  • composted vegetable scraps,
  • composted manure,
  • bone meal,
  • and seaweed.
  • Natural materials–unlike the agricultural chemicals listed above–provide organic matter that supports beneficial soil organisms and your plants.

(4) Control pests in the least harmful way possible by, for example:

  • handpicking pests,
  • installing barrier netting,
  • and mingling companion plants.
  • The goal is generally not to eliminate pests, but to keep them at acceptable, tolerable levels.
  • Use pesticides approved for organic growing only when necessary, as a last resort. 

(5) Focus on prevention.

  • For example, mulch to thwart weeds.
    • Mulches from natural materials such as wood chips, shredded leaves, and hay are especially beneficial for the soil. (See 3.)
    • Mulch also helps to regulate soil temperature and keeps your soil moist.
  • Learn about the pests and diseases you commonly see in your garden and take appropriate action before they damage your plants. Here’s a very useful guide to the pests, weeds, diseases, and disorders we might see in our region.
  • Rotating crops helps to keep your soil healthy and also disrupts the life cycle of pests and pathogens that thrive on particular crops and conditions in your garden.