In temperate climates, perennials are a supplement, not a substitute, for annual vegetables. They offer a great alternative to intensive cultivation. They are a great way to make part of your garden low-maintenance and productive year-round--not because they bear year-round, but because they bear when annual crops cannot.

In the future I think they'll play a bigger role, partly because of the search for low-till, low-input alternatives. But also because more people are growing them and saving seed. Our annual crops are varied, big, succulent, and mild-flavored because they've been grown and selected over the centuries for those qualities. As perennials are grown more, they will diversify and be shaped to suit people's desires.  They will have larger yields. In turn, more people will grow them. We can be the generation of gardeners to re-start that process.

Perennials from various climates that have been cultivated for a long time--especially if they've been cultivated for market--have lost their wildness and become easy to sprout and grow. Sorrel, bunching onions, erba stella, rhubarb, asparagus, artichoke, and chives are as easy to grow as annual crops, produce abundantly, and are choice edibles. 

In mild climates, where plants don't go all the way dormant, some will perennialize. Tree Collards and Perpetual Spinach are examples of leafy greens that produce over a very long period and are native to mild maritime climates. Quite a few varieties of collards and kales produce a percentage of perennial offspring. Celery, chard, and arugula all have perennial varieties. Artichokes are classic Mediterranean perennials. With these, the limitation isn't getting them to sprout, it's getting them to survive the winter. Good drainage is often key to carrying these mild-climate plants through  winter. They do well with compost, sun, and a porous soil. On clay, it's often best to make a mound with rock, soil, and plenty of compost then plant on that for good drainage.

Lovage and Alexanders are celery relatives that are still partly wild;  they need cold-conditioning (stratification) before germinating. But given moist soil and time, they sprout pretty well. The easiest way to do that is to plant them in fall or very early spring. Or the damp seeds can be chilled  in the fridge. They both do well in semi-shade. I have them just outside the canopy of fruit trees, where the soil is moist and fallen leaves make an effortless mulch.

I imagine rhubarb evolved along streams in woodlands, where they would have the semi-shade and rich moist soil they love. Every few years, you should dig up and separate the crowns (which should have multiplied.) When you replant, dig a deep hole and fill it with the richest food you've got--manure, unfinished compost, food waste, grass clippings, alfalfa meal, fish waste--you get the picture. In Alaska we used fish guts and got beautiful big stalks. The smellier the fertilizer, the deeper you need to bury it to keep animals away. But rhubarb will go deep enough to find it--I've seen it make roots as big as a man's leg.

Wild or perennial plants from northern regions can be challenging to even experienced gardeners:  Good King Henry, Spinach Vine, and Alpine Strawberry are good examples. They are programmed to stay dormant through the winter and sprout, a few at a time, in spring.  Success with them depends on mimicking that schedule, so they too should be planted in pots outdoors in the winter. They will do best in woodsy conditions of shade and soil. Strangely enough, true dandelions are also a challenge to sprout when and where you want them. Their seeds can go dormant in the soil for long periods, and sprout a few at a time over a period of years--a great pattern for a weed, but not for the kitchen garden.

The usual method of fertilizing perennials and controlling weeds is to apply mulch to the soil around them. Fallen leaves are ideal, so if you have fruit trees or broadleaf shade trees, this is an excellent use for the autumn leaves. Wood chips (Use chipped branches for preference rather than the trunk wood) are another good mulch. Straw, compost, or even dead weeds are fine, but do not use spruce or cedar needles, Black Walnut leaves, decorative bark, or plastic.

Spruce, cedar, and especially walnuts contain compounds that act as natural herbicides, weakening nearby plants. Some plants (Many bulbs, beans, bluebells, corn and squash for example) are immune to the poison, but most are not. If you do have black walnut trees, perennial edibles that can thrive under or around them are currants, elderberries, miner's lettuce, multiplier onion, bunching onion, and wild plum. I have a hedgerow with elderberries, currants, comfrey, walking onion, and miner's lettuce on the shady end, and sage, perennial arugula, catnip, and feverfew on the sunny end.
The whole hedgerow grows in walnut-tainted soil, but the shady end is right under the walnut canopy. Grass will grow under walnuts as well, so it's a very pleasant shady refuge in summer.

The hedgerow plants have a lot against them--in shade, coping with herbicidal compounds from the black walnut, and in soil fully colonized with tree roots--yet they survive and thrive. That is what's possible when you broaden your choices past the usual annuals and fruit trees to include less-common trees, shrubs, herbs, and perennial vegetables that are adapted to your conditions.

This summer's heat waves have left parts of my garden that need replanting and repair. Whether your garden plans have blossomed or crashed, there are choices to make now for the rest of the season.  The hours when it’s tolerable to work outside are limited, so it really helps to have a clear and concrete plan. If your priorities are clear, you can go to work without delays or indecision.

Of course you have to water, weed, and harvest the plants you already have. Many of them may need a top-dressing of compost soon to keep them productive. There may be pest problems, overgrown areas, weather damage, or the inevitable garden failures. All must be addressed.  But if you miss the window for starting new crops, your garden may peter out in August.

One solution is to write down your 3 most urgent tasks for existing plants, and your 3 most urgent new plantings to make.  You can tackle both your #1 tasks, then move down the lists.

For example, your biggest concerns might be that your tomatoes must be tied up before they collapse in a heap, the weeds are out of control, and your bush beans and lettuce are going by.  One plan you could make would be to spend your first garden session tying up those tomatoes and  while you're there sowing some lettuce in their shade. Your next garden session might be to cut down your old lettuce, run a hoe over the ground, and plant a succession crop of bush beans there. And your next few sessions might be to plant a few pots of winter vegetables and weed one small area each time.

Your priority may be a task like weeding or seed-starting. Or you may prioritize an area. You could make one bed your priority and do all the weeding, staking, tying, top-dressing, and replanting that small area needs rather than doing just one job over a larger area. What's important is to use the time you have to do the things that are most important or most time-sensitive. If you go out to the garden with your priorities clear in your mind, chances are you'll get a lot done.

July and August are important months for starting new seeds. Some may be direct-sown in the garden, others will be best in flats for transplanting later when space is available and conditions are right.

What to start is often confusing, so I've sorted them into groups to make decision-making easier. There are five types of summer plantings you can make now:

First, you might need to replace dead, dying, or spent plants. If you don’t have a replacement ready, either direct-sow the replacement, cover the area with mulch, or sow buckwheat as a quick soil-building cover crop. Fast-growing herbs like dill and basil are good options for bare spots. Leaving the area bare for even a week invites weeds and more work down the line.

Second, sow succession crops. Bush beans, corn, root crops, determinate tomatoes, lettuce, greens, sunflowers and even zucchini are all going to stop producing before the warm season is over. Now’s the time to start another wave of beans and lettuce, or a different crop to use the space. Cucumbers, bush beans, and chard are fast-growing and heat-tolerant options. Even if you already have some in production, new plants will be more vigorous and productive. Salad is often best started in a container in part shade.

Third, many herbs and flowers can be sown now. Quick-growing annuals like basil, cosmos, and coreopsis are great companion plants for late-summer pest control. Biennials and some perennials need sowing now so they can size up enough to bloom next spring.

Fourth, you need to start winter vegetables early enough for them to be productive. Brussels sprouts, cabbage, broccoli, kale, collards, and rutabagas need a long growing season, so start them soon. You don’t need to have garden space for them yet. Find a place in dappled shade or with only morning sun and start them in pots or in a bed set aside as a nursery.

Fifth, fall specialties need to be started now so they are ready to eat before hard frost. Fennel, endive, chicory (radicchio), carrots, turnips, beets, and chard make fall meals special and are best planted from now until mid-August. Fennel  especially will not stand hard winter frost, but bolts easily when planted in spring. It is at its best planted in July and August, as are all of the endive/chicory tribe.

Pots or flats need to be where they have light, but won't dry out or scorch. In cloudy, humid, or cooler climates, full sun may be fine. But if you have clear skies, dry heat and blazing sun, arrange for a place with morning sun but afternoon shade. An east-facing porch or on the east side of a shade tree is good. Sometimes indoors under lights or in a window is the best option. A frame or hoops covered with shade cloth is another option.  Wherever they are, be vigilant, as pots dry out quickly.

From now through the end of June it’s time to plant the most straightforward and gardener-friendly crops of all--summer annuals. Beans, corn, squash, zinnias, and sunflowers have been grown in North America for thousands of years. You can plant their big, easy-to-handle seeds straight into the ground once frost is over and the soil is warm. Many summer flowers like cosmos, coreopsis, and marigolds thrive in the same conditions.

These crops were perfected by Native farmers who used a digging stick and a hoe--no tractor, no plow, no greenhouse, not even a spade. They don't need a perfect seedbed. What they do need is organic matter. They were originally grown in forest clearings, in soil created by centuries of fallen leaves. You can give them a great start by working compost into the top 2’” of soil.

All of the summer annuals like warmth and organic matter, but each has its own niche. Rather than get into endless detail, I've highlighted three important points for each vegetable

1. What unique strength it has
2. What it needs most from you
3. What's the most common problem to watch for

Beans are renowned for their ability to enrich the soil. Colonies of special bacteria in their roots are able to use nitrogen from the air as a food for the plant. But roots can't climb out of the soil to access that air--it has to be in the soil. Compacted, hard, mineral soil doesn't have spaces for air. Organic matter provides the meeting place of soil, air, and water where roots can make optimum growth and nitrogen-fixing bacteria can thrive. 

Give beans the best start by working in compost, or even old potting soil, crumbled leaves, or rice hulls to make air spaces. You can start breaking up deep compaction by using a broadfork or garden fork to loosen soil slightly. Just walk down the bed sticking in the fork every 8-12" and rocking it to let in air. If you've already planted, you can stick in the fork without rocking it, to make air holes 6"-8" away from your planted row.

Pitfalls to watch for are weeds and overheating. Use mulch or shallow hoeing to prevent weeds from competing with your beans. Beans are very sensitive to competition, and weeds will reduce your harvest substantially.
When the temperatures rise above 85, consider using shade cloth over your bean plants. Most beans prefer the same temperature range that humans do, and stop producing in very hot weather. It’s also worth seeking out heat-resistant varieties like Rattlesnake and King City Pink.

Corn uses sunlight in a way that's unusual in our gardens but common in tropical plants. It's called C-4 photosynthesis and it makes corn (and its cousin sorghum) extremely fast-growing in summer, right through the hottest weather.

Your job is to provide enough water and fertility to sustain that fast growth. It’s traditional to give corn a source of nitrogen in the furrow when planting. Manure, compost, alfalfa meal, fish emulsion, blood meal etc can be buried under the seeds. Make a deeper-than-normal furrow, put in the manure or whatever, then a layer of soil (easy to do by running a hoe along the edge). Then you can sprinkle your seeds into the furrow and cover. They should be 1" deep. Water well if needed, and be sure that your corn gets water as it grows. If the leaf tips turn brown or yellow, or the leaves get yellow streaks, or growth is slow, you probably need to water more. If water isn't available, thin the plants to avoid competition, and mulch well.

Corn's pitfall can be poor pollination, resulting in missing kernels. To prevent it, plant in blocks at least 5 feet square rather than in a single row. Corn pollen is spread by wind rather than insects. Planting in a cluster helps the pollen from the top tassels to fall onto the ears and pollinate them. It’s important to keep cucumber beetles from eating the silks for the same reason. (each strand of silk is a tube that pipes pollen down to a kernel. Once the kernel is pollinated, the silk starts to shrivel.) You can get sticky traps that attract the beetles with natural pheromones and capture them on the sticky surface without using pesticides.

Squashes superpower is their vigor. They shade the ground with big leaves that romp over the competition and out-compete most weeds. All types of squash, both zucchini and winter squash, love growing in a compost pile. This tells you three things: They like a lot of nutrients. They sprout best in warm, moist places. And they aren't picky about how "finished" the compost is. They will grow in stuff that's downright chunky and stinky, turn it into food, and grow like crazy.

When you're planting squash is the time to bury your kitchen waste, half-finished compost, rotten fruit, moldy dog food, or even dead gophers a foot (or 2 if it's dead or fishy) below the seeds or transplants. (More prosaically, use some feathermeal, alfalfa meal, or compost.)  They are great pioneer plants in new gardens--just cut down the weeds, put down cardboard or black plastic, and plant your squash in openings 4' apart. Mulching with pulled weeds or grass clippings will also give them a gradual nutrient boost.

Their weak points are pests and diseases. Inspect the underside of leaves for rows of oval brown eggs laid by the dreaded squash bug. Squish the eggs and coat the crown of the plant and the stalks with diatom dust. Surrounding your plants with nasturtiums, radishes, or other brassicas can deter squash bugs by masking their scent. In the south, borers are a big problem. One of the three main cultivated squash species, C. moschata, is much more resistant to borers than the other 2 species (C. pepo and C. maxima.) Butternut and Tromboncino which are both C. moschata.

As fall approaches, spray with compost tea, water with a bit of yogurt blended in, or other probiotic brews to prevent mildew. In fact, take measures against mildew whenever the humidity is high and temperatures are in the 70-85 range. Even if the daytime is dry, the onset of heavy dew in fall can be a problem.

Cucumbers, melons, and watermelons are members of the squash family from India, Persia, and Africa. Their vines are on a smaller scale than squash; still easy to grow and vigorous, but with smaller leaves and thinner stalks. They prefer a  more cultivated soil, finished compost, and mulch. Their smaller vines don't shade out weeds like the larger squashes do, so you need to control weeds with mulch or cultivation. They're still vines, though, and need water and fertility early in the season to fuel their growth. Like squash, they are prone to fungal diseases and should get probiotics. Cucumbers are best trellised to save space, make picking easier, and prevent downy mildew from sitting on damp soil. A thick mulch of straw and putting tiles, bricks, rocks, or other barriers under each melon will protect them from both damp and rodents.

Summer flowers and annual herbs like zinnias, coreopsis, sunflowers, basil, dill, and marigolds are not just the icing on the cake. They are a vital link between the garden and the rest of the world. Pollinators, pest-eating predators, birds, butterflies, and humans are all drawn into the garden when you add some flowers and herbs to each garden row. They are the garden's protectors.

Adapability is another strength. Flowers aren't heavy feeders, and don't have to ripen fruit. So you don't have to give them the best spots, or go to great lengths to please them.  I tend to put them in the corners of the bed, where conditions are likely to be less perfect than in the middle. If you have areas where tree roots intrude, there is a bit too much shade, or the soil is rocky, that's a good spot to try some flowers.

Your job is keep the sown areas moist until you see sprouts. Both flowers and herbs are sown very near the surface, so they can dry out easily. In summer heat and especially with any wind, that may mean watering twice a day, or covering until germination.

An early problem to look out for: overcrowding. Thin them to the recommended spacing. A clump of many seedlings in a tiny space will not produce more flowers--it will produce stunted plants that never make a show. Cutting the flowers (or removing dead ones) will provoke the plant to flower more. Here are some suggestions for using them:

I like small marigolds at the feet of tomatoes, and basil alongside peppers. Zinnias, taller marigolds, borage, or Glowing Embers cosmos make great accents at the ends of each vegetable beds. I find veggies often don't do well at the ends or corners where fertility or irrigation may not be as good; flowers cope with the drier, more compacted conditions just fine.

If you want the cheerfulness of sunflowers but can't find a place for large flowers, consider using them as light shade over beans, kale, lettuce, or other plants that dislike overheating. Or you can use them as a trellis for pole beans. Sow the sunflowers, let them get 8 inches tall, then sow the beans, one per sunflower. Plant in groups of three, so the sunflowers forma triangle  18" on a side. That way they make their own tripod support. The wandering, twining bean vines will hold them together.

Morning Glories are the loveliest way to hide an ugly view, dead stump, wall, or bare bank--the long vines cover the offending item, then cover themselves with magical blue trumpet flowers. At the opposite extreme, coreopsis and Sensation cosmos have such feathery leaves that you can see through them; they cast next to no shade.  I scatter them in the beds to add interest and attract beneficial insects--coreopsis among short plants, and cosmos with tall ones. Dill is similar. When they are an inch or two high, thin to the recommended spacing. Picking flowers will stimulate the plant to make more, so enjoy!

This time of year, different places may have wildly different conditions, from almost-summer to lingering-winter. But the sequence is the same, no matter where we are along it. There are many things you can plant almost everywhere in April-May.
Here's a breakdown.

Spring crops are the most important focus now--their planting window is limited. If you're in a warm zone, do a good big sowing  before it's too hot. If you're in a cold zone, make first sowings, remembering that spring crops can take some frost.

Even if it's quite warm out, make sure the soil is moist, not soggy, before you plant. Test it by grabbing a handful of dirt and squeezing. Does water come out like wringing a sponge? Don't plant yet.  Next, nudge the ball of soil. If it crumbles, you're good. If it sticks together in a gooey ball, wait. Waterlogged soil will make your seeds rot.

Greens: Spinach, lettuce, Asian greens, mustard greens, cima di rapa.

Peas: Sow every two weeks. Early sowings should be trellised for pea production. You can still make sowings into summer for harvest as pea shoots for salad and light cooking.

Roots: Get carrots in before the soil dries out--they love a wet start. Parsnips take a long time to sprout and need a long season, so get them going. Both of them (and parsley too) sprout much faster if you soak the seeds for 4-6 hours before planting and rinse well.  Don't leave them soaking more than 24 hours max. Rinse well and plant. It's also planting time for beets, turnips, burdock, onions and leeks.

Summer crops that want a cold start: Some plants from cold-winter regions are programmed to start in cold soil even though they grow and produce all summer. Sunflowers, quinoa, and calendulas are all best planted in April, even where it's still cold. Grains like barley and spring wheat are also in this category. 

Crops that are normally transplanted outdoors after sowing inside need to get used to outdoor conditions gradually. Even after your last frost date, nights will be much colder outdoors. Wind and weather put further stresses on seedlings. Cold-hardy crops like cabbage, kale, broccoli, and Brussels Sprouts need minimal adjustments, and can go outdoors while light frost is still a possibility, but it's best to avoid windy or very hot days.

Tomatoes, beans, squash, corn, and other tender crops should not go outside until at least your last frost date. (Find it here)
Peppers, melons, eggplant, and cucumbers are best planted into very warm soil--at least 2 weeks after your last frost date, when the weather is settled and the soil is quite warm.

Before planting, pull mulch aside to let the soil warm up, and let your potted transplants "practice" being outside by putting them outdoors for longer and longer periods over the course of a week. Covering them at night is also a possibility for "hardening off," as the process of adaptation is called.

The same conditions apply for direct-sowing in the garden as for transplants. I like to sow large-seeded crops like squash, corn and beans directly into garden soil, waiting until the soil is warm after my last frost date is past. Take time to work in compost first.