Perennial vegetables

I have a somewhat unfair view of traditional ornamental gardeners as lacking in imagination, gardening in a certain way because that’s how it’s always been done (admittedly they can be creative with their color and plant combinations but imagination should go far beyond that). However there is one area where we food gardeners can (and definitely should) learn from them. They don’t replant their entire garden with annuals every year, but mainly rely upon perennials to keep their gardens full of plants. We can do this too, using perennial vegetables; food crops that stay in the garden permanently, requiring minimal attention and getting bigger and better every year (of course they also use shrubs and trees too and so can we, but that’s for another post).

If any plants are going to be low maintenance it is very important to choose the right species for your garden and this applies particularly to perennial vegetables. If you don’t do this, they may not produce much of a crop and may not even survive. These plants will be in the ground year round so climate is the biggest factor and largely determines which ones will grow well in your garden (much more so than with annuals). Soil fertility is also important in some cases. A few perennials can survive total neglect for years – I overlooked some Jerusalem Artichokes for about 5 years and they somehow managed to survive summer heat, shade, 5 months of drought and even gophers (they didn’t produce a crop during that time though).

A lot of the best perennial crops are native to the tropics (where perennial vegetable gardening is much more common) and don’t do well in colder climates. I live in a pretty mild climate and even though most winter nights in my garden are above freezing, we always have just enough frosty nights to kill off the most tender plants. There aren’t a lot of cold climate perennials vegetables (though still many more than are commonly used), simply because they haven’t been a high priority with plant breeders (or gardeners). However there could be a lot more if we really tried (many wild edibles are just waiting to be domesticated).

The perennial vegetables don’t really belong in the annual vegetable garden, as having plants in the ground permanently really complicates soil preparation and rotation schemes. Also many only produce food at one time of year (for some plants this may be only a few weeks), but take up space year round (sometimes a lot). If you want to grow them in beds then give them their own dedicated perennial beds around the edge of the vegetable garden. They can also work in other areas of the garden and I often put single plants in any vacant space that provides the right conditions. Many of these plants are pretty robust and only ask for enough sun and water. Some (many) are attractive enough to go in the ornamental areas, while others can be used as groundcover or in the forest garden (I find they can work well in the irrigated patches around my fruit trees).

Even though I live in a gardeners paradise it isn’t the best place for perennial vegetables. My biggest problem is gophers, which will inevitably find (and usually eat) any unprotected plants. This means I have to plant them in wire baskets if I want to be sure to keep them, but as they grow they often spread out of these protected areas, where they eventually get eaten. Another issue is irrigation, as I have to water most small plants during the driest months (even the most drought tolerant plants are more productive when watered regularly). When faced with such uncertain conditions I find it’s best to not have all of my eggs in one basket (or plants in one place). One lapse and they can all be gone (all 25 of my beautiful thriving Mashua plants were wiped out one summer by a negligent house sitter). Starting over isn’t a very big deal with annuals, but it can be a big problem with hard to find perennials. The best insurance against losing plants is generosity, just give plants to any competent gardeners you meet. Then if you lose yours due to some unforeseen catastrophe they can give some plants back to you.

The biggest obstacle to growing many perennial vegetables is finding material to plant. They aren’t very popular so few places sell them, which is a paradoxical situation because if they were easier to find more people would grow them. Trying to find many of these plants in North America is difficult (Rampion, Turkish Rocket, Ramps, Mediterranean Saltbush, Seakale) and sometimes almost impossible (I’ve been trying to find Ulluco for years). This situation is somewhat ironic considering how easy many of these plants are to propagate and grow. Hopefully this situation is starting to change as more people start to grow them. It would be nice if every area had its own plant exchange network.

Perennial vegetables aren’t a garden panacea. Many don’t turn out to be as low maintenance as we might imagine and most need some attention from time to time if they are to really perform (if you neglect them they may struggle or even die). Perennials aren’t usually as productive as annual vegetables and it would be difficult to live entirely on them. It would also be a very different diet as many perennial vegetables are unfamiliar foods and to use them regularly you have to make a little more effort in the kitchen. If you grow them, but never actually use them then they are ornamentals and a waste of space. However they provide another layer of low-work productive plants for the garden and this makes them very worthwhile (essential even).

Temperate zone perennial crops to start with

Some perennial vegetables are already fairly familiar as vegetable garden residents, including asparagus, rhubarb, globe artichoke, horseradish, strawberry and Welsh onion. These plants are all great additions to the food garden because they just mind their own business and produce an annual harvest in their season. They are also widely available and so provide a good introduction to the pleasures of perennials. There are also some less obviously perennial, but still familiar, vegetables such as shallots, garlic and Jerusalem artichoke. However these are usually grown as annuals in that they are dug up and replanted every year (you don’t have to though).

There are some excellent perennial leafy greens, including dandelion, chicory, good king Henry, sorrel, wild rocket (Diplotaxis muralis), tree Kales (and tree collards) and Turkish rocket (Bunias orientalis). These plants tend to be defined by their vigor and independence, they require nothing from you and will often self-sow too.

Perennial roots vegetables include Chinese artichoke, groundnut, Jerusalem artichoke, oca, mashua, skirret and yacon. These have all done fairly well in my garden, though their usefulness varies enormously.

The perennial herbs: Bay, Chives, Lovage, Marjoram, Mints, Oregano, Rosemary, Sage, Tarragon and Thyme are already familiar garden perennials. It’s good to have some of these near the kitchen door for cooking, but I mostly treat them as ornamental perennials and have them scattered all over the place. Most have been in my garden for years and get no care at all, though some benefit from being divided and replanted occasionally (in which case I take cuttings from the most vigorous new growth). They grow so easily that you can soon have far more than you can use in the kitchen. I found that tender Stevia can survive the winter in my garden and it has become an important new herb.

There are also a lot of great wild vegetables out there (in the wild and in gardens), including chufa, creeping bellflower, groundnut, day lily, dandelion, ramps, stinging nettle and watercress.  Once you get these established they are true no work perennials and really do grow themselves, so harvesting is the only work required. Getting them started is not always as easy as you might think though and in some cases it can be quite a bit of work (they may need quite specific growing conditions or may be hard to start from seed). Domesticating edible wild plants is an area that holds great potential for creating new perennial crops and is well worth exploring. Of course you should always be aware of the danger of introducing an exotic wild plant to new areas, where it could potentially naturalize and become a problem.

There are also many good exotic perennial vegetables (canna, chayote, lotus, water chestnut, water spinach), though they are too frost tender to be considered low-maintenance in colder climates. They require extra work to keep them alive, so you only grow these plants if you really want them.

If you want to experiment with perennial vegetables you might start with a trip to your local produce market. You will find Horseradish root (break it up and plant it – each piece will grow into a separate plant), Jerusalem Artichoke (Sunchoke) tubers, Shallot bulbs and Watercress (a bunch of cut plants root easily in a glass of water) and maybe some chayote fruit (plant the whole fruit and it will sprout), All of these will grow with almost no effort on your part. You can also go to your local garden center in early spring and find Asparagus, Rhubarb, Strawberry and Globe Artichoke plants (all of these can easily be grown from seed too).