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Ask the Gardener: Here’s the dirt on home soil-testing kits

Ask the Expert Gardening
Mark the date on your calendars: April 22 is the 50th anniversary of Earth Day. Associated Press/File

What to do this week: Many people are planning vegetable gardens this year. It can be a life-changing project, especially for kids. Vegetables require a lot of attention. There’s a Chinese saying: “The best fertilizer is the shadow of the gardener.’’ But if you think you may not be going anywhere except your backyard for a long time, this may be a sanity saver. Plant peas, spinach, and lettuce soon, as they stop producing when temperatures rise.

Q. The soil-testing service at the University of Massachusetts Amherst is closed, so I will have to test mine myself. I am looking for advice on how to choose a kit. There are so many options!

J.T., Northampton

A. The staff at the UMass lab is working remotely and can offer an interpretation of past analyses, guidance on lime and fertilizer recommendations, check on the status of current orders, and answer questions on other related topics, according to the website. E-mail soiltest@umass.edu for more information.

Soil tests can tell you what nutrients your earth is lacking so you can add the right fertilizer and, even more important, what the pH is so you can neutralize it if it is preventing your plants from being able to utilize that fertilizer. A pH of 6.5 is best for most plants. When in operation, UMass will also measure lead in your soil, but most home soil-testing kits don’t do this; you’ll need one specifically for lead. Regardless, don’t grow vegetables near a house built before 1978, when lead paint was outlawed, because it can persist in the soil. A raised bed filled with purchased soil should be safe.

To check your soil, I would buy a do-it-yourself kit, so you don’t have to mail samples to a lab and can get fast results. The LaMotte Garden Kit, Luster Leaf 1601 Rapitest Soil Test Kit, and AccuGrow Soil Test Kit have good reputations in this category. If you need to know only your soil’s pH, Garden Tutor Soil pH Test Strips are good. There are also some adequate soil probes for testing pH, as well as light and moisture levels, including the Atree Soil pH Meter and the Sonkir Soil pH Meter, MS02-3.

 

Q. I am growing flowers from seed this year. My sweet peas are at 6 to 8 inches and just starting with their first leaves. When should I move them into pots?

M.K., Milton

A. Edible peas (Pisum sativum) and sweet peas (Lathyrus odoratus) are each among the most rewarding seeds you can sow directly in the garden right now. Both need cool weather and constant moisture. Plant peas 1 to 2 inches deep and 3 inches apart in a mostly sunny area where they have something to climb. But although they can be treated similarly, don’t mix edible peas such as English, snap, and snow with strictly ornamental sweet peas, which are pretty but poisonous! Many people start peas indoors by sowing one or two seeds in each peat pot, preferably on a heating mat to aid germination. After they sprout, usually within two weeks, turn off the bottom heat and place them in a bright window or under grow lights. After they develop four true leaves, snip off the tips to encourage side branching. Because pea plants resent transplanting, move your seedlings directly into the garden (instead of into larger intermediate pots ) about five weeks after planting. But first take a week to harden them off by moving their trays outdoors for a few hours each day. If your seedlings are too close together in the garden, thin them with scissors. I tie netting to poles to make a trellis, but you can also make a teepee from tall canes or even use an old ladder. You may need to tie the vines up so they don’t flop. Mulching will help keep their roots cool and moist. Don’t let them develop pods, or they will stop flowering.

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