Category Archives: Garden Advice

Garden Advice

Choosing the Right Soil Amendments

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Healthy soil is critical to good production, but no-one starts with perfect soil. Successful gardeners add amendments to their soil to adjust its pH, texture, nutrient levels, and other properties over time. Understanding soil amendments can help you choose the right ones to add to your garden.

Start with Soil Tests

To avoid wasting time and money, it’s a good idea to start with soil tests so that you will know exactly what you need. There are a couple of different soil tests you can do.

Soil Texture: The Jar Test

For this test, all you need is a jar, water, and a sample of your soil. It’s easy to complete at home and can give you information on the type of soil texture you have, like clay, loam, or sand.

Learn how to complete the jar test here.

Comprehensive Soil Testing

While there are some at-home soil tests that give information like pH, we recommend growers opt for a comprehensive soil test through their local extension agency or agricultural college. These soil tests are cheap and offer a wealth of information about the available nutrients and pH of your soil. Experts at the facility can also make recommendations on how to amend your soil based on your test results.

Learn more about having your soil tested here.

Soil Amendments to Add Organic Matter and Improve Soil Texture

Once you have your soil test results, you can start improving your soil. Few gardeners are blessed with loam right off the bat, so most will need to work on soil texture. Whether you have sand, clay, or silt soils, these amendments can help build up organic matter, improve drainage, reduce compaction, and improve water retention.

Compost

Finished compost is hands down one of the best soil amendments, no matter what your soil is like to start. Finished compost adds nutrients, adds organic matter, and improves soil texture. There’s no risk of overdoing it with finished compost; you can actually fill raised beds with nothing but compost.

Learn to make your own compost at home.

Aged Manure

Aged manure has similar properties to compost and is often available at garden supply centers in bags. If you don’t have enough compost, it can be an affordable way to add organic matter and nutrients to your soil while improving soil texture.

Generally, we don’t recommend adding fresh manure to a bed. Fresh manure has the potential to burn plants, and it can run off during the rain, adding nitrogen and other nutrients to local watersheds, which contribute to toxic algae blooms.

You should also be careful about sourcing manure that isn’t specifically for garden use. Unfortunately, the widespread use of herbicides in the United States means that animal hay and feed is often contaminated. When livestock like horses and cattle eat food containing herbicides, these chemicals pass into their manure and then into your garden, where they will kill vegetable crops.

A bioassay test can help you determine if manure is safe to use.

Sphagnum peat moss soil amendments
Ragesoss, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Peat Moss or Coconut Coir

Peat moss improves soil texture, increases acidity, and is a good option for loosening heavy clay soils. However, we now prefer not to use it because it’s a non-renewable resource that’s harvested from peat bogs.

Coconut coir is a sustainable alternative for potting mixes, but can be too pricey to amend a large area. Unlike peat moss, coconut coir doesn’t make the soil more acidic.

Vermiculite or Perlite

Vermiculite is a naturally occurring mineral that looks like little golden-brown or silvery-gray pebbles. In the soil, it improves aeration and drainage. It also acts like a sponge, holding and slowly releasing moisture, which is why is a popular ingredient in seed starting mixes.

Perlite is a natural volcanic glass that looks like little white rocks. In the soil, it improves aeration and drainage and reduces compaction. Like vermiculite, it’s popular for seed-starting mixes.

Other Options

Mulch and cover crops are great options to use with soil amendments to improve soil texture. As these break down, they will loosen the soil and add organic matter. Some of our favorite mulches for adding organic matter include old leaves, wood chips, grass clippings, and straw.

Buckwheat, wheat, rye, oats, and sunn hemp are good cover crops for adding organic matter and improving soil texture. Daikon radishes are another good cover crop option, especially for heavy clay soils, as their large roots can help break up hardpans and improve drainage and aeration as they break down.

Soil pH of North America Map
Soil pH of North America Map from the University of Wisconsin – Madison Center for Sustainability and the
Global Environment (SAGE)

Soil Amendments to Adjust Soil pH

Soil pH measures how alkaline (basic) or acidic your soil is on a scale from 0 to 14. On the pH scale, a value of 7.0 is neutral, while numbers below 7.0 are acidic and numbers above 7.0 are alkaline.

All crops have an ideal pH range, but for most vegetables this is slightly acidic to neutral, falling between 6.0 and 7.0. Soil that’s too alkaline or too acidic can prevent crops from easily absorbing nutrients. Soil amendments can help you adjust your soil pH to reach the ideal range for your crops.

The natural soil pH of soil ranges by region. In the eastern United States, most gardeners will find that they are starting with acidic soil.

Learn more about soil pH affects plants.

Lime

If you have soil that’s too acidic and need to raise the pH a bit, agricultural lime or dolomitic lime made from crushed limestone are great choices. When mixed into the soil, they release compounds like calcium carbonate or magnesium carbonate, which react with excess hydrogen ions in the soil and raise the pH.

While lime is the most common option for amending acidic soil, there are also a few other options like biochar or wood ash.

Sulfur

To lower your soil pH and make it more acidic, garden sulfur is the most common choice. Sulfur releases hydrogen ions into the soil, gradually reducing the soil pH. Some gardeners use garden sulfur or fertilizer with sulfur for acid-loving plants like blueberries, azaleas, or hydrangeas, some of which turn blue in acidic soil.

Other options for lowering soil pH include pine needles, peat moss, and fertilizer.

Fresh vegetable scraps in a compost bin
Goyojona, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Soil Amendments to Add Nutrients

While having rich, fertile soil is a good thing, it’s important to remember that too much of any one nutrient can also lead to problems. For example, too much nitrogen will cause lush foliar growth with little fruit or root development in plants like tomatoes and sweet potatoes.

Agricultural experts divide nutrients into two categories. The first is macronutrients, which include primary nutrients nitrogen, phosphorus, and potassium, and secondary nutrients sulfur, magnesium, and calcium. The second category is micronutrients or trace minerals and includes boron, chlorine, copper, iron, manganese, molybdenum, and zinc. While these are still important to plant health, they’re needed in such small quantities that it’s less likely your plant is deficient in one of these micronutrients.

For this post, we’ll focus on macronutrients and the soil amendments that can help you add them into your garden.

Nitrogen Rich Soil Amendments

There are many ways to add nitrogen to your soil. Depending on your needs and product availability, you can increase nitrogen levels with bone meal, fish emulsion, liquid kelp, cottonseed meal, coffee grounds, soybean meal, compost, manure, or fertilizer. You can also grow nitrogen-fixing legume cover crops in your rotation to keep nitrogen levels up each season.

Phosphorus Rich Soil Amendments

You can add phosphorus to your soil using rock phosphate, greensand, compost, or bone meal.

Potassium Rich Soil Amendments

Good potassium sources include manure, compost, seaweed or kelp meal, potash, granite dust, greensand, and wood ashes.

Sulfur Rich Soil Amendments

Add sulfur with gypsum, compost, or sulfur.

Magnesium Rich Soil Amendments

To correct a magnesium deficiency, add limestone, manure, compost, or greensand.

Calcium Rich Soil Amendments

Use oyster shells, eggshells, limestone, gypsum, or fish meal to add calcium to your soil.

While a soil test will give you the best information, you can also learn to recognize signs of deficiencies in your plants. Check out our previous post, Common Signs of Nutrient Deficiencies in Plants.

Garden Advice

How to Grow Egyptian Walking Onions

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If you love green onions, Egyptian walking onions are a great choice for your garden! They’re hardy perennial onions that will last for years and spread well once established to keep you in a steady supply.

The walking onion gets its name from the way it spreads. The plants produce bulbils at the top of the stalk. When these mature, they weigh down the top so it flops over and plants them in the soil beside the original plant. This clever adaptation gives them the appearance of slowly walking across the garden.

You may also hear folks call these onions tree onions or top-setting onions.

How Do You Use Egyptian Walking Onions?

We primarily use Egyptian walking onions for their delicious green tops. While they die back some in winter, they come up early and provide greens throughout the spring and fall. You just want to avoid over-harvesting while your plants are getting established. The greens are excellent in scallion pancakes, stir-fries, salads, and pasta sauces.

You can also harvest the immature bulbs are the base of the onions, but they are very hot. The bulbils at the top of the plant are also edible. When they mature, they are covered with a papery purple or red skin and taste similar to bulb onions, though their size makes them a bit more time-consuming to process.

Soil Preparation for Perennial Onions

Walking onions aren’t super fussy about soil and will thrive in a range of soil types where traditional bulb onions fail. That said, they still perform better in areas with loose soil texture. The bulbs and roots need adequate air and water.

Sandy loam is ideal for Egyptian walking onions, but not every gardener is that lucky. If you have heavy clay or nutrient-poor sandy soil, the best thing you can do is work to build up the bed’s organic matter. Mixing in compost, aged manure, rotted sawdust, or peat moss will improve soil texture. Cover crops like buckwheat are another great method for adding organic matter to the soil.

Like other alliums, walking onions do best in soil with a fairly neutral pH between 6.5 and 7.0. A soil test is a great idea. Soil that’s too alkaline will slow their growth. To raise the pH by adding dolomitic limestone or wood ash. To lower the pH, add sulfur dust or fertilize with ammonium sulfate. Test your soil again next year to see if it’s at the optimum pH.

Signs of Nutrient Deficiency

If you have poor, nutrient-deficient soil, you’ll see symptoms in the onions. Yellow-green stalks can indicate a nitrogen deficiency, while light green, slow-growing stalks could indicate a phosphorous deficiency. Plants with a potassium deficiency can have light green stalks, browning tips, and poor bulb development.

Use a fertilizer that suits your soil’s needs. Most commercial products show the ratio of primary plant nutrients as a three-number ratio, such as 5-10-5, that represents nitrogen-phosphorus-potassium. You can also use products like fish emulsion or aged manure to help raise nitrogen.

Egyptian walking onions with sprouting bulbils
Dave Whitinger, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons

Selecting a Site

Walking onions do best in full sun, and you want to pick a spot where they’ve got a bit of room to spread out. Remember that your walking onions will last for years and produce a nice large bed. We suggest you select a permanent location outside of the area that you would normally rotate your annual crops through.

Raised beds are a good option for walking onions if you have tough, compacted soil. They’ll grow well in raised beds, but may need to be watered more frequently during the summer.

Planting and Caring for Walking Onions

We recommend planting walking onions in the fall, like you would garlic. In moderate climates, like here in Virginia, we plant from mid-October to mid-November. Cooler or hotter areas will need to adjust their dates. If you purchase walking onions from us, we’ll ship them to you based on your zip code, starting with the northernmost areas.

Plant the bulbs or bulbils about 1/2 to 1 inch deep in moderate climates or deeper in cold climates. Cover with 2 to 3 inches of mulch, such as straw or old leaves, after planting. Space your plants about 9 inches apart with room to spread and grow around them.

Keep your walking onions weeded and mulched, especially as they get established during the first year. It’s also good to keep up with watering during the first year, providing about one inch per week, though they become more drought-resistant as they get established. When caring for established plants, you should only need to water during prolonged dry periods. Onions in raised beds and pots will dry out more quickly and need more frequent watering.

You can replant bulbils or divide your patch in the fall to create a larger bed of onions. Wait to harvest the bulbs for transplanting until the stalks have dried back and turned brown. Don’t delay, as they can re-sprout in as little as one week. Harvest the bulbils for planting when they are fully grown and plump but before they dry out or sprout. 

Harvesting Egyptian Walking Onions

It’s a good idea to harvest sparingly during the plant’s first year while they get established. Then, depending on your climate, you can begin harvesting green shoots in late winter or very early spring. In summer, the greens get tough and dry, but trimming back the plants will cause them to send up more tender stalks. Fall and early winter are also great times to enjoy your walking onions as green onions.

In late spring or summer, you can also harvest the bulbils from the plant tops. Typically, we save the largest, nicest bulbils for replanting, but you can also use them for cooking. We love using them to flavor pickles!

Garden Advice

How to Grow Cauliflower in the Fall

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Cauliflower can be a tricky crop to grow, especially for southern gardeners. A member of the cabbage or brassica family, cauliflower thrives in the cool temperatures of spring and fall. While cauliflower may survive light frosts, it isn’t winter hardy, so growing it in much of the Southeast means finding a sweet spot between temperatures that are too hot or too cold. These tips can help you grow finicky fall cauliflower with success.

When to Plant Fall Cauliflower

Southern gardeners can grow cauliflower anytime the weather is consistently cool and they can avoid the risk of hard frosts. For those in the Deep South, cauliflower may be a good winter crop.

Cauliflower is highly sensitive to temperature. It grows best when the temperature is consistently between 60° and 65°F. If the temperature is too hot, cauliflower will form stunted heads and bolt, or go to flower prematurely. Wait to plant cauliflower outdoors until temperatures are consistently below 75°F.

You also want to plant your cauliflower early enough that you can harvest the heads before it gets too cold. Cauliflower can tolerate light frosts, but prolonged exposure to temperatures below 32°F will damage the curds, making them rubbery.

Days to maturity can vary for cauliflower depending on the variety you select, when you plant, and the weather. For fall-planted crops, we recommend adding 15 days to your cauliflower variety’s expected ‘days to harvest’ to account for dwindling fall light. Those days should begin when you transplant the cauliflower out into the garden, not when you start seeds indoors.

Start Your Cauliflower Indoors

While you can direct-sow cauliflower, for fall gardens its best to start your plants indoors. Even if the weather is still too hot for cauliflower to germinate and grow, you can get the plants started in a cool spot indoors.

Cauliflower can get leggy and weak without adequate light. Most growers will find they need supplemental lighting to start cauliflower and other plants indoors.

Read more about starting transplants indoors here.Cauliflower plant in raised bed

Soil Preparation

Cauliflower can also be picky about its soil requirements. If possible, have your soil tested. Cauliflower thrives in fertile soil with a pH between 6 and 7.

For good production, cauliflower needs consistent nutrients throughout its growing period. Amend your soil with finished compost or aged manure before planting. Fertilize with a well-balanced fertilizer if necessary.

Transplanting Cauliflower

After hardening off, transplant your cauliflower seedlings out into the bed on a cool, overcast day. Cauliflower needs plenty of space as it matures, so plant it 18 to 24 inches apart in rows 30 inches apart.

Watering, Weeding, and Care

Cauliflower requires consistent moisture throughout its growth period to produce firm, nicely flavored heads. Cauliflower plants that experience drought can develop off-flavors or a mushier texture. Water consistently if you’re not getting at least one inch of rain per week, especially if you have sandy soil, which drains more quickly.

Ensuring your plants aren’t competing with weeds will also help your cauliflower develop. Weed frequently using a hoe to kill small weeds, but be careful not to damage the plants. Using mulch can also help reduce weeds and keep the soil cool and moist.

Cauliflower Pests & Diseases

Unfortunately, cauliflower is susceptible to several pests and diseases, including cabbage worms, flea beetles, black rot, and downy mildew. Cabbage worms, also called cabbage moths or cabbage loopers, are what we most frequently see gardeners struggling with, and they can be particularly troublesome in the fall after breeding all summer.

To conquer the cabbage worms, visit our guide to organic cabbage worm control.

Cauliflower plant with small head forming
Buddy431, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Blanching Cauliflower

If you want white cauliflower, you need to blanch the curds. When the white head or curd begins to form, tie the top leaves together over it to protect the curd from sunlight, which causes the curd to yellow. 

Don’t do this for purple or yellow cauliflower or romanesco! They need the light to develop full color.

Harvesting Cauliflower

Cut your cauliflower heads when they are large and firm. If you leave them too long, the curds will become loose and open, and they will lose flavor. Usually, this is slower in the cool temperatures of fall and winter. Don’t harvest when heads are wet, or the curds will mold in storage.

Cauliflower heads will typically last a week or two in the refrigerator when harvested properly. You can also blanch and freeze cauliflower for later use.