Category Archives: Garden Advice

Planting for Pollinators: Black Swallowtail Butterfly

Eastern Black Swallowtail

As a garden lover, you know that pollinators are in trouble. For decades now huge amounts of pesticides have been dumped on US crops in order to control pests (335 million lbs in 1965, up to 948 million lbs by the year 2000, as the bugs keep gaining resistance.) At the same time pollinator populations are being destroyed. Compounded with the chemical stress, they are losing their food sources as more invasive species of plants that they cannot eat crowd out native species. It’s up to us enthusiastic gardeners (even if you’re not quite as enamored of all the creepy crawlies as I am) to plant the first line of defense and grow with an eye not just to our plates, but to the care of our buggy friends. We know from how quickly our Insectiary Mix gets snapped up that people want to be doing this, so we’d like to offer more in-depth information about particular pollinators and how to attract and care for them.

Butterflies are an easy sell for gardeners. Unlike wasps and bees, no one is afraid of them, and they make a beautiful addition to any garden. Moreover, butterflies help to pollinate your plants and feed your songbird population. While adult birds can live well on seeds and berries, nestlings are unable to digest these yet and require juicy caterpillars to help them grow. Without a steady supply of caterpillars arriving at the nest – it takes thousands to feed one clutch – baby birds starve to death. Read more here.

The Eastern Black Swallowtail is a wonderful candidate to attract to your garden. They are efficient pollinators and their striking black wings dabbed with yellow and blue are a delightful sight among the flowers. There are hidden benefits too: the caterpillar of the black swallowtail smells bad to predators and helps to deter them from your garden. The black swallowtail has a large range, covering all but the northeastern part of the United States, and extending well south into Mexico.

So what can you grow to draw these lovely critters? Black Swallowtail caterpillars feed on plants in the Apiaceae family – that’s carrots, dill, fennel, parsley, celery, caraway. Keep in mind that feeding caterpillars means sacrificing some plants, so if you’re trying to feed yourself too it’s a good plan to grow extra plants that you won’t mind sharing with the caterpillars.

A quick guide to recognizing the black swallowtail in all its stages:

Eggs: tiny yellow spheres on leaves and stems, turn brown before hatching (actually, it’s turning translucent and the brown is the caterpillar seen through.)

Caterpillars: They grow in 5 instars. Starting out black and spiky, they moult to light green striped with black with yellow spots, with a little spike in each yellow spot. The last three instars are similar, but often with more light green at each and spikes disappearing.

Pupa: The skin splits to form chrysalis (no cocoon like with silk moths), held on to a twig with a thread harness. It can be green or brown. The last generation of the season overwinters as a pupa, for as long as nine months.

Adult males have more yellow, females more blue on the wings, and a wingspan of about 7-8.5 cm.

More about black swallowtails.

Black Swallowtail Caterpillar

Cover Crops for Great Green Manure, Mulch, and More

By Ira Wallace

Warm weather and late April rains have our fall-planted crimson clover, winter rye, and Austrian winter peas growing like weeds and just starting to bloom.  As an edible bonus, the winter peas gave an abundance of sweet pea shoots to add to salads all winter and spring. The bright red flowers of crimson clover provide much-needed pollen and nectar for pollinators and other beneficial insects in spring.

To select the best cover crops for your garden, consider which functions are your priorities, the time of year, and how long the cover crop will be in the ground. Cover crops are important tools all year for filling in gaps between crops while also preventing soil erosion, suppressing weeds, providing habitat for pollinators, and improving fertility. Some even provide an edible bonus, for you and for pollinators. Here are some cover crop favorites in the Southeast.

Winter Nitrogen Fixers – soil fertility out of thin air.

  • red-Clover-2-GryphonClover (crimson, white, and red Sow clover six to eight weeks before your average first frost date. Clovers fix nitrogen in the soil and thus boost nitrogen for next spring’s garden. Mow one or two times when about half of the crop is flowering. Allow the residue to decompose for at least two weeks before planting vegetables.
  • Hairy Vetch– Sow hairy vetch six to eight weeks before the average first frost date. This vine-like, vigorously-growing, cold-tolerant, winter-hardy, annual legume adds nitrogen and builds soil organic matter. Hairy vetch grows well in cereal grain mixtures and is an excellent spring weed suppressor.
  • Pea shoot and Brassica Flower xaladWinter Peas (Austrian)– Sow winter peas four to six weeks before the average first frost date. Sometimes called “black pea” and “field pea”, this is a cool-season, annual legume with good nitrogen-fixing capabilities. Usually planted with rye, oats, or barley to reduce the chance of winter kill. Cut and turn under at full bloom for maximum nitrogen.

Winter Soil Builders and Subsoil Looseners – for the surface or deeper down.

  • Winter Rye (Cereal Rye)
    Sow winter rye six weeks before the average first frost date and up to two weeks after. A cold-hardy crop, winter rye will grow well into the spring. Winter Rye increases soil organic matter as it decomposes. Mow one to two times when at least 12 inches tall, or when half of the crop has immature seed heads. Allow residue to decompose for at least two weeks before planting vegetables.
  • Oats – Sow oats eight to ten weeks before the average first frost date. Oats are killed by the hard frosts. They form a winter surface mulch, preventing erosion and increasing soil organic matter as they decay.

Edible Cover Crops

Traditional gardeners in the Southeast plant a big bed of winter greens (turnips,  mustards, kale, and collards) to keep the garden covered and provide fresh eating until spring.  Plant this beautiful edible greens cover crop in August or September to build organic matter and provide healthy meals all winter long. Try a mixture of the old Southern favorites and contemporary choices like Seven Top turnip, Lacinato kale, Red Russian kale, Southern Giant Curled mustard greens, and Tatsoi.

If you are in the upper South or in the mountains, cover your winter greens with row cover or plant in a cold frame for winter harvests. Left uncovered in cold winters, the leaves will be too damaged for good eating, but you’ll have fresh new growth in early spring if winter lows aren’t too bad.

For more reason to plant cover crops read our Cover Cropping for Unpredictable Weather


Warm Season cover crops and filling in the summer gaps

  • Sorghum-Sudan Grass hybrid Plant in spring and summer, beginning after the soil has warmed and up until six weeks before first frost. This hybrid is unrivaled for adding organic matter to worn-out soils. These tall, fast-growing, heat-loving summer annual grasses can smother weeds, suppress some nematode species, and penetrate compacted subsoil.


  • pink-eye-purple-hull-webSoybeans (Edamame) and Southern Peas (Cowpeas)
    Plant in early summer through mid-summer, between spring and fall crops. Mow before pods have formed or when pods are still green and have not matured. These legume family plants can fix nitrogen for an added bonus.
  • buckwheat-webBuckwheat
    Plant from spring through early fall when the ground will be open 5 weeks or more. Buckwheat establishes quickly, suppresses weeds and attracts pollinators. Mow one to two times when half the crop is in flower and before hard seeds have formed. Will be killed by frost.

Although fall through winter is the most common time when gardeners grow cover crops, savvy gardeners include summer cover crops in their garden plans. No matter which cover crops you choose or when you fit it in your garden rotation, cover crops allow you to grow your own nitrogen and organic matter in place.

When to Mow or Turn Under Cover Crops

A lot of factors go into determining the best time to turn under or at least cut down your winter cover crop. To get the most biomass, wait until half of the cover crop is in flower but make sure to get it cut down and incorporated before it goes to seed. Some freshly cut cover crops like winter rye inhibit seed germination for the following crop. If you are planning to direct seed allow 2 to 4 weeks for your cover crop to decompose before planting. This same property can be an advantage in weed suppression if the cover crop is just crimped or rolled and left as a mulch for transplanted tomatoes.

Another factor to consider is when you want to plant the next crop. For early spring plantings you may need to cut and turn in your cover crops well before flowering and allow a longer time (maybe 3 to 6 weeks) for the organic matter to decompose before planting. You can speed up decomposition of the cover crop 1 or 2 weeks by sprinkling in some mature compost or applying compost tea to add beneficial soil organisms before turning it under.

For most home gardens you can cut your cover crop with a hand sickle or scythe and add it to your compost. This leaves the considerable roots to add organic matter and aerate the soil. You can also weed-eat it or mow it and just let it lay there on the ground as mulch or till it in.  For the home gardener, Roto-tilling  is the fastest and easiest way to incorporate your cover crops, but you can also spade in your crop residues the old fashioned way. Digging in your covers crops aids in faster decomposition and less nitrogen loss into the atmosphere.


Sweet Potatoes, Potatoes, or Both? Decide for your garden.

ginseng sweet potato (slips for spring planting)dark red norland (seed potato)

Don’t be fooled: potatoes and sweet potatoes may share a name, but these two crops are grown very differently. We’ve broken down some of the differences to help you decide what to grow:

Plant Family: Genetically, potatoes and sweet potatoes have little in common. Potatoes hail from the Solanaceae family: their closest relatives are tomatoes, peppers, eggplants, and other nightshades. Sweet Potatoes are most closely related to morning glory: they are in the family Convolvulaceae.

Crop Rotation: Sweet potatoes should be easy to fit into a crop rotation, while potatoes may be quite difficult. Potatoes should be rotated by 3-4 years with nightshade crops, while sweet potatoes only need to be rotated with themselves.

Plant Starts: While potatoes may be grown from any sprouting spud, it is best to start from disease-free Seed Potatoes. Sweet potatoes may be started at home by sprouting your own slips (green shoots off the mother root to be separated and planted), or the slips may be purchased.

Timing: We ship seed potatoes from March through April, directly from our grower’s farm. Our Virginia-grown sweet potato slips begin shipping in May.

Planting: Potatoes don’t mature well in hot weather, so it is best to start an early spring crop (we start ours in March) and grow a fall-maturing crop for best quality roots for winter storage (we start a second crop in June). It can be difficult to find seed potatoes after April, so order seed potatoes in the spring and store them in the refrigerator until planting time. We plant our heat-loving sweet potato slips in June.

Yields: Yields vary, but high-yielding sweet potato plants often produce as much as 5-10 pounds per plant. Potatoes may yield 3-5 pounds per plant, but this will depend on hilling: the new potatoes are produced above the seed potato, so new soil needs to be piled over the plants throughout the growing season.

Storage: Both sweet potatoes and potatoes can be stored for months without refrigeration. Light-sensitive potatoes must be stored in a cool, dark place (preferably 40-45°F). Sweet potatoes can be stored at room temperature so long as they are kept in the dark (otherwise they will start sprouting at temperatures above 70°F or so).

Check out our full Sweet Potato Growing Guide and Potato Cultural Notes.