All posts by Lisa Dermer

Summer Sowings: Continuous Harvests all Summer and into Fall

With summer’s intense heat in full swing, it can be hard to remember to sow cool season crops, but some fall crops need to be started as early as June, and many need to be started in July.

On our farm in central Virginia our average first fall frost falls in late October, but even where frosts come later or not at all you should start fall crops during the summer. Later plantings will struggle with fall’s low light levels, and won’t produce before growth slows to a near standstill in early winter (the “Persephone Days,” November 21-January 21).

To make sense of all the seeds we’re sowing during the summer months, I divide our summer plantings into three types:

1. Warm-season, slow growing summer successions: these are the bonus crops that many gardeners forget. A second round of tomatoes, summer squash, sweet corn, or cucumbers can keep you harvesting all summer long without interruption.

2. Fast growing summer successions: these crops require frequent, regular sowing all through summer. Because we’re sowing so often, these can be easier to remember. We sow beans, carrots, salad greens, beets, and radish seeds weekly. Be ready to baby your summer sowings: we water daily to keep them from drying out before sprouting. Lettuce needs the soil temperature to be below 80 degrees F, so you may need to sow in flats indoors, or even in the refrigerator, or sow in the evening and cool the soil with crushed ice.

3. Cool season, slow growing crops for fall harvest. We sow the Brassicas first: Brussels sprouts in June, and then broccoli, cabbage, and cauliflower in July. By mid-July we’re sowing fall greens: collards, Swiss chard, leaf beet, and kale, plus winter radishes. We sow Chinese cabbage in late July. Sow thickly in nursery beds and keep up with your watering; we protect these young plants from summer’s insects with spun polyester row cover or the new more durable and temperature neutral “proteknet.”

For further resources on planning your summer sowings, check out: Brett Grohsgal’s article Simple Winter Gardening, our article on Summer Succession Plantings, and our Fall and Winter Planting Guide.

Successions can be overwhelming, so we have some tricks that help extend harvests with fewer plantings:

1. Plant indeterminate varieties of tomatoes and cucumbers, and pole-type beans and peas. We still find we need a late tomato planting, because our earliest plantings taper down toward the end of summer (and our Heritage Harvest Festival at Monticello needs lots of tomatoes for the Tasting Tent).

2. Select heirlooms bred to provide extended harvests: many modern farms want concentrated harvests that can be harvested with one or two passes; but for more traditional growers an extended harvest was the ideal way to manage the bounty. Look for roots that hold well in the ground. Lutz beets are one of our favorites: they can be spring planted and will hold all summer without turning woody. However, they will be very large, so this only works if you’re happy cooking with multi-pound beets (try slicing cross-wise for beet burgers). Open-pollinated broccoli provides extended side-shoot harvests. Choose bolt-resistant greens and harvest by the leaf before before taking whole plants.

3. Choose seasonally appropriate salad greens: we want salads all year-round, but this can be tricky both when it’s hot and when it’s cold! Mustards and brassicas are more mild in cold weather, so get adventurous by adding young kale and tatsoi to winter and early spring salads. Choose cold-tolerant lettuce: red varieties tend to hold up better in frost. For hot weather, choose fast-growing summer crisphead lettuce like Sierra, or heat-ready greens like Red Malabar spinach or Golden purslane.

4. Set up a root cellar or similar storage system. Ultimately, some of your crops will ripen all at once, or you’ll be faced with a glut of produce when frosts threaten. Be prepared: have a proper storage area ready to go for your carrots, parsnips, turnips, cabbages, winter squash, and more. Be ready to finish ripening the last fresh tomatoes indoors. For fresh produce through till spring, we need good systems for storing and slowly working through the harvest. Nancy Bubel’s Root Cellaring is an invaluable resource if you’re looking to improve your winter storage system, and has lots of low-cost and little-time options, if you haven’t blocked off your whole summer to dig a cellar.

Garlic and Perennial (Multiplier) Onions: Harvest and Curing

Lisa Dermer & Ira Wallace

Harvesting and curing garlic and perennial onion bulbs is a balancing act: the crop shouldn’t be harvested too early or too late; the curing (drying) process should not be too fast or too slow. Luckily, with a little know-how it’s easy to hit the sweet spot and maximize your harvest of high-quality bulbs with excellent storage quality.

Preparing for the Harvest

As a guideline, know the estimated harvest time for the varieties you’re growing (this can vary quite a bit by type), but be ready to start checking your bulbs earlier. Warm, sunny weather will bring on maturity sooner, and waiting too long may damage the bulbs. On our Central Virginia farm, the beginning of the harvest has varied by up to 3 weeks (late May to mid-June). 

A few weeks before your estimated harvest date, pull off the mulch around the bulbs and irrigate less, or stop watering altogether. This will prevent rotting and toughen the skins for storage.

The Garlic Harvest

Keep an eye on your garlic plants: as soon as one third of the leaves turn yellow or brown the bulbs are probably ready to harvest. If you’re unsure, use this simple test to check: dig up a sample bulb and cut it in half: if the cloves have separated, your garlic is ready. If the bulb is still one undifferentiated mass, you should wait a few more days.

There should be at least 4–6 green leaves remaining at harvest. Do not wait for the tops to turn entirely brown and dry before harvesting your garlic! By then the outer scales will have decayed — the ones that hold all the cloves together in one smooth-skinned bulb. If you wait too long and these leaves die, you’ll have ugly bulbs that are hard to clean and keep poorly in storage. (If your harvest is delayed and all the leaves have turned brown on some of your garlic, use those bulbs first because they won’t last as long in storage.) 

If the soil is very dry, lightly irrigate the night before your harvest. Carefully loosen the soil next to and under the bulbs using a digging fork. Don’t just pull garlic out of the ground. Be careful not to bruise or cut the bulbs — give them a wide berth by keeping your digging fork 10-12 inches away from the plants, and inserting straight down before lifting.

Gently remove excess soil from the bulbs using your fingers or a soft brush (don’t bang the bulbs against each other!). The tender freshly-dug bulbs need to be handled carefully to avoid damage. Keep the bulbs out of the sun and rain until you can bring them indoors. Don’t wash them. Curing (see below) is the next step in handling your harvest. 

The Perennial (Multiplier) Onion Harvest
Shallots are the best known type of perennial onions, also called multiplier or potato onions. Perennial onions are grown from a bulb rather than seeds or sets: they’re planted in the fall and harvested in late spring, just like garlic.

Prior to harvest, the neck region of multiplier onions weakens and the green tops begin to fall down. When you see the first sign of this, pull off any mulch from around the plants and stop watering: this lets the skins toughen for storage.

When approximately 50% of the tops have fallen, the crop has sufficiently ripened and is ready for harvesting. There is no advantage to breaking over the tops of onions still standing (in fact this may shorten the storage life of certain varieties). Not all the tops fall over at the same time. You can harvest the mature onions every few days. Harvest those with tops still standing after 7–10 days: keep these separate from the rest and eat them first because they will not keep as well.

To harvest multipliers, pull the clusters or gently dig them out. Try to do this during dry weather. Don’t leave the bulbs exposed to hot sun or rain and don’t wash them. Lay the tops over the freshly harvested bulbs until you can bring them under shelter. See below for the next step: curing. 

Curing (Drying) Garlic and Perennial Onions

Curing is a fancy word for properly drying your bulbs. A good cure improves the flavor, storage quality, and hardiness of both garlic and perennial onion bulbs. The goal is to dry the outer wrapper layers completely while keeping the bulbs or cloves plump and deliciously aromatic. It takes anywhere from 3 weeks to 2 months to properly cure bulbs.

Many factors influence the rate of curing, including humidity, temperature, air circulation, the size of the bulbs, and the number of green leaves at harvest. High humidity can slow drying, so give your bulbs plenty of space, good ventilation, and complete protection from rain. Drying too quickly can cause shriveled bulbs that don’t store well, so dry bulbs out of direct sunlight and away from extreme heat.

We cure our bulbs on the upper level of our pole barn. We use fans to make sure the area is adequately ventilated and to keep the humidity low. You can make your own low-cost exhaust fan by fitting a box fan tightly in a window frame (fill any gaps around the fan for a tight fit).

We hang our garlic to cure: for soft neck garlic you can make braids, though this can be time-consuming. Otherwise use a slip knot that will tighten with the necks as they dry and shrink. To do this, just fold a string in half, then pull the two free ends through the loop, and cinch this around several necks. Then tie the bunch to the main string (or wire, rafter, rack, etc).

We cure our perennial onions on shelves made with hardware cloth. You could also hang a stretched sheet or other breathable material or mesh. The onion necks may break as they dry, so hanging them can lead to bulbs falling and getting bruised.

Every few days check for and remove any spoiled bulbs, being careful to handle the bulbs gently and as little as possible. The high water content right after harvest lets bulbs bruise easily, making them susceptible to rot. Once curing is complete, the bulbs are much less easily damaged.

Once curing is complete, separate the individual perennial onion bulbs from the clusters. For both garlic and onion bulbs, cut the dried tops 1 inch above the base and trim the roots to ¼ inch. Your bulbs are now ready for eating, storage, or planting.

Growing Rhubarb from Seed

by Ira Wallace

Many gardeners are familiar with growing rhubarb from divisions or crowns, but if you want to start a large rhubarb patch quickly, without spending a lot, growing rhubarb from seed is the answer. The stems of rhubarb grown from seed will not all have that intense red color you might be used to. Some stems will be red, some green, and some in between. But they will all taste the same, perfect for your home-cooked pie. If you want all red stalks, get divisions from a friend or neighbor or buy crowns from your local nursery.

When starting your seeds, remember that rhubarb is a cool-weather crop.

  • In climate zones 6 and cooler, it’s an easy-to-grow perennial (traditionally planted where there used to be an outdoor privy). The stalks and leaves die back with first frost in the fall, but the plants will come right back in early spring.
  • In zones 7 to 8, growing rhubarb is tricky. but it can be grown as a short lived perennial. You will need to be careful to shelter your rhubarb plants from extreme summer heat. Choose a location with afternoon shade in the summer. The north side of a grape arbor, raspberry patch, or asparagus ferns would work well.
  • In areas with very hot summers, where winters are mild (zones 9 to 10), rhubarb can be grown from seed as a winter annual. ECHO ("Educational Concerns for Hunger Organization") in Florida has had good luck with planting rhubarb seed in August and harvesting in March-May. The variety Victoria is noted as a productive late summer/early fall started annual from almost subtropical Florida to semi-arid northeast Texas. Read how to do this in “Growing Rhubarb from Seed as an Annual” below.

Starting Rhubarb Seeds

Rhubarb seeds are encased in a large paper-like shell. To speed germination, soak your seeds in water for 1-2 hours before planting. If you’re starting indoors, plant the seeds in screened compost or other suitable organic planting mixture, 2 seeds per 2 to 3 inch pot. Using peat pots or cow pots makes transplanting easier. For spring plantings a heating cable or mat will speed the germination if the room temperature is below 70°F. Rhubarb seeds germinate quickly when planted in the warmth of late August or early September. Keep your seedlings evenly moist but don’t over-water (the seedlings can die from root rot if the ground is too wet).

Growing Rhubarb from Seed as a Perennial

To start rhubarb in the spring (zones 8 and lower), sow seed in pots or flats under cover 8-10 weeks before your average last frost. Transplant the young plants out into the garden about two weeks before your average last frost, into an area amended with compost or well rotted manure and plenty of organic matter. The plants should be about 4 inches tall. Mulch your seedlings to maintain even soil moisture and keep the roots cool. Harden plants off before transplanting or protect the new transplants with row cover until danger of frost has passed.

Choose a location protected from the heat. The warmer your climate, the more important it is to provide afternoon shade (on the west and south) during the hottest months. A row of tall annual plants (your late summer tomatoes or pole lima beans), shade cloth, or a temporary structure can provide adequate shade that you can remove when the weather cools. Always remember to maintain even moisture. Letting your young rhubarb plants dry out in hot weather is the kiss of death.

Growing Rhubarb from Seed as an Annual

To grow rhubarb as an annual in the fall and winter (zones 9 and higher), start the seeds in a cool location (a bright indoor spot or a shady outdoor place) from late August to early October. Transplant into the garden when the seedlings reach about 4 inches tall. The plants will be ready for harvest in March through early May. Intense summer heat will kill the plants, so harvest all the leaves in late spring. This technique only works where winters are very mild, or if you can protect the plants from damaging frost with a cold frame or row cover.

Harvesting Rhubarb

Harvest rhubarb either by cutting or pulling off the leaf stalks at soil level. When your plants have 10 stalks you can harvest 3 or 4 stems at a time per plant.  If you are growing your rhubarb as an annual harvest the entire plant. Harvest stalks only! DO NOT eat the rhubarb leaves as they contain high levels of toxic oxalic acid.

For perennial plantings let some leaves remain on the plants during summer to generate energy and reserves for the following year. We recommend harvesting a few stems at a time, in spring and fall only. It’s best not to stress the plants during the summer, so avoid harvesting at this time. Frost will kill all the leaves, so harvest all the leaves when frost threatens in the fall.

Break off and discard any flowering stalks at ground level. (The flowering stalks don’t make good eating, and breaking them off prevents the plant from putting energy into flowers and seeds.)

It’s best not to harvest during the first year if you are establishing a perennial bed. For annual beds, harvest all remaining stalks when the weather begins to get too hot in the summer.

Ira Wallace lives and gardens at Acorn Community Farm, home of Southern Exposure Seed Exchange, where she coordinates variety selection and seed growers. Southern Exposure offers 700+ varieties of non-GMO, open-pollinated, and organic seeds. Ira is a co-organizer of the Heritage Harvest Festival at Monticello. She serves on the board of the Organic Seed Alliance and is a frequent presenter at the Mother Earth News Fairs and many other events throughout the Southeast. Her first book, “The Timber Press Guide to Vegetable Gardening in the Southeast,” is available online and at booksellers everywhere.