pH matters

It’s the time of summer when there aren’t enough hours in the day. In addition to gardening and swimming and planning a wedding, my job for the Damariscotta Lake Watershed Association is also much more time consuming and busy in the summer. I haven’t had much time to write, though it doesn’t mean nothing is happening in the garden.

Garden on July 5th

Some crops seem to grow overnight. The pumpkins and potatoes are huge. The tomatoes and cucumbers and brassicas look great. But the onions and corn leave much to be desired. We’ve been trying to figure out why the onions have done so little even though they were the first seedlings we put in the ground. My father suggested the problem could be pH.

Many crops do best in slightly acidic to neutral soil with a pH between 6.5 and 7. Soil pH affects the chemical forms of nutrients like phosphorus and iron. When soil pH is too acidic or too alkaline, some nutrients convert to a form that cannot be absorbed by plants. Even in nutrient-rich soil, off-balance pH may cause plants to suffer nutrient deficiencies

In Maine, soil is often too acidic for optimum plant growth. Luckily, soil pH can be easily raised by spreading and mixing in ground limestone. When we got our soil tested in the spring, we found out that the pH was 5.6. We spread 350 pounds of lime and 65 pounds of wood ash (about half the recommended amount) and tilled it in. However, we expect that the lime hasn’t had time to completely do its work.

Potatoes are one crop that does grow well in more acidic soils, preferring a pH of 5.5. We didn’t spread any lime in our potato area, and the potato plants are enormous. The onions, however, prefer a pH of 6-7.

To see if we could solve the low pH in our onion patch, we dumped some wood ash around the plants. Wood ash raises pH and is more water soluble than limestone. We only had enough ash for part of the onion row. Today, after the rain had a chance to wash the ash into the soil, the part of the onion row we treated seems to be greener and larger. Before we spread ash on the rest of the onions, we’ll take a picture so we can assess the results more concretely.

We’ve decided to do an experiment with our tomatoes. Some people prune their tomatoes to improve their yield. Tomato plants sprout suckers where new leaves leave the main stem. When pruning, you cut these suckers off. I’ve always wondered whether pruning tomatoes really makes a difference. This summer we intend to find out. We pruned one side of the row and left the other half untouched. We’ll weigh the fruit we get from each side.

First batch of cucumbers and dill

Our first crop is ripening: cucumbers. We were very excited to make our first jar of pickles!

I’ve been adding lots of pictures to the Photos page of chicks, plants and more. Check them out!

In case you’re interested, I found this list of pH preferences for different crops:

  • Beans            6.0-7.0
  • Beets             6.5-8.0
  • Broccoli        6.0-7.0
  • Cabbage       6.0-7.5
  • Cantaloupe  6.0-7.5
  • Carrots         5.5-7.0
  • Corn             5.5-7.5
  • Cucumbers 5.5-7.0
  • Lettuce        6.0-7.0
  • Onions         6.0-7.0
  • Peas             6.0-7.5
  • Peppers       5.5-7.0
  • Potatoes      4.8-6.5
  • Squash        6.0-7.0
  • Tomatoes   5.5-7.5
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s