Urban Agriculture Projecturban agriculture

Crop rotation seems to be one of those topics that people get intimidated about when they’re starting out… perhaps it most often comes up during that second spring when they’re getting ready to plant again.  In any case, it is really a simple practice that is as straightforward as it is necessary, so I thought I’d try to sum it up for you in as few words as possible.

When you’re growing plants in a garden, you usually have a wide variety of families of plants, all of which have slightly different diseases and nutrient needs.  Root crops, for instance, use more phosphorus than do leafy greens.  Also, plants that fruit such as tomatoes use more nutrients than plants that are harvested at an earlier life stage, such as lettuce.  And then there are the legumes (peas, beans, favas, etc.), a family of plants that as many know capture nitrogen and store it in their roots, thus adding this nutrient to the soil.

So, in planning a crop rotation, it is important to know what family a crop is from, and also if it is a heavy feeder, a lighter feeder, or a legume.  An understanding of some of the key diseases that you’re trying to avoid is good too!  I’ve summarized the main garden veggie families below, with some pertinent information on each.

Alliums This family includes onions, leeks, garlic, shallots, chives… you get the idea.  They are heavy feeders, and suffer from several fungal root diseases in our climate, so rotation is really important!  Generally they stay in the ground for long periods of time and are quite pungent.  They are not broadleaf plants unlike most other veggies, and so are for the most part not susceptible to the same types of fungi and diseases.  I think this combination of traits seems to help subdue insect pests too, so I like to grow them in my rotation.  They do however seem to have a negative effect on legumes if I try to plant them immediately after, so try to leave some space and time between them and your peas or beans.

Asters (Asteraceae aka compositae) This is the largest plant family, but only a few are grown as veggies.   Most are grown in the flower garden, or are weeds!  This family includes lettuce, artichokes, salsify, black salsify, sunchokes (aka jerusalem artichokes) and a few veg garden flowers like marigolds and sunflowers.  These are generally light feeders and easy to grow, and especially with lettuce, since it is in the ground for such a short time, disease-free with ideal conditions.  However, if you have poor drainage, not enough sun or poor airflow, do rotate often.  Viruses are also a problem later in the season, so it’s a good idea to plant fall crops away from spring sown lettuces if you see signs, like mottled, thickened leaves.   A note about sunchokes: they are very invasive as you may know, so I don’t suggest rotating them around your garden!  If you choose to grow them pick one area (preferably contained) and treat them as a perennial.

Brassicas (aka Crucifers) This family includes broccoli, cabbage, cauliflower, kale and the like, as well as most Asian greens like bok choi, tah tsai, Chinese cabbage, and mizuna, upland cress, arugula, radishes, rutabagas, turnips, horseradish, mustard and canola.   Several common garden weeds are also of this family, like shepherds purse and wild radish.  This family is generally a light to moderate feeder, requiring some lime since they tend to uptake lots of calcium and magnesium.  They are pretty tough but can be susceptible to mildews.  They are all susceptible to clubroot, a long-lived soil disease that damages the roots (roots become thickened, nobly, woody), and lives there for 7 years without a host… so if this is a problem you need an 8-year rotation, and to also exclude all the weeds of this family for the full 7 years.  Email me (help@tgibc.org) if you need help this problem… it’s challenging!

Curcubits This includes cucumbers, melons, squashes and zucchini.  They are heavy feeders and tend to get mildew, though often it has little or no impact on production.  They do get root rots though this seems to me to have more to do with our weather than crop rotation issues -they are very heat loving and cannot handle our cool wet springs.

Chenopodia (aka Goosefoots, Goosefeet? ) Another big family, with weedy and veggie members.  This family includes beets, chard, spinach, amaranth, quinoa, orach, mangels.  Light to moderate feeders, this family is fairly hardy but can have problems with rust fungi or root rots.  Generally insects are the main issue, including wireworms, cutworms,  and leaf miners.

Legumes This family, as mentioned, includes peas, beans, broad (fava) beans and soybeans, as well as cover crops/green manures like clover and vetch.  Legumes are very important to include in your rotation especially if you do not plan on adding copious amounts of rich compost or fertilizers, since this is the only family of veggies that adds nitrogen to the soil.  This happens through beneficial Rhizobium bacteria that live symbiotically in the roots of the legume, so if your legumes are not thriving, pull a few up and check to see if the roots are ‘nodulated’.  If your soil has enough Rhizobium the roots will have several nodules on each branch- pinkish oval/oblong bumps that are firmly attached.  If nodulation does not happen very much or at all, you can purchase garden innoculant from a garden centre and try planting again.  The bacteria once established will usually survive for years in an area, so long as you keep growing legumes.  When you remove your legumes at the end of the season, cut rather than pull the plants to leave the nutrients in the ground, mulch and plant some winter veggies or a cover crop there!  Keep in mind that legumes do use the other nutrients though, and make sure to lime at least.

Nightshades (aka Solanaceae) This family includes tomatoes, potatoes, peppers, eggplants, tomatillos, ground cherries, cape gooseberries, tobacco and nicotiana.  These are heavy feeders and are highly susceptible to fungal diseases (especially blights) and viruses carried by aphids which can overwinter in soil or stray potatoes, so rotation is critical.

Umbellifers (aka Apiaceae) This family includes carrots, parsnips, fennel and celery, as well as several herbs including dill, parsley, lovage, cilantro, chervil, cicely and angelica.  These are moderate feeders and very tough and easy to grow, though they prefer loamy soils or humus-rich light soils and even moisture.  In heavy soils they do tend to have fungal root problems and must be rotated diligently.  They are highly attractive to beneficial insects such as bees and ladybugs when in bloom, and are said to be excellent companion plants, especially to tomatoes.

So now that you know all the background information you need, the thing to do is to figure out how much space you want to allot to each family and how many years you want to rotate for.  Divide your garden into beds or zones of beds that will share the same family(ies) in a given year.  Keep in mind the nutrient needs of the groups too.

I’ve outlined 8 families here, but you needn’t have an 8 year rotation!  If you mainly grow carrots, peas and tomatoes, then you can simply do a 3 year rotation of these crops with 3 or 6 beds, or do fours, and use those 3 families, plus one other bed and year to fit in any oddball crops that you grow limited amounts of.

For example, I like to do a 3 year rotation.  I have 7 beds, so this is great.  One of them becomes used for short-lived perennial herbs and as a test plot for new plants. This gets rotated but only sporadically.  It’s big enough that I can rotate things around within the bed as needed.

The other 6 are paired up.  I grow alliums in 2 beds; garlic in one and leeks, shallots and onions in the other.  Since I know these are heavy feeders, I plant them where my legumes were growing last, and give them compost, lime and bone meal too.

In another 2 beds (where the alliums were previously), I plant 1 bed with a mixture of umbellifers and solanums (carrots, cilantro, tomatoes and tomatillos), and the other is a mixture of umbellifers, asters, chenopodia, and brassicas (parsley, lettuce, beets, broccoli and salad greens of various families).  These get a lighter dose of compost while the tomatoes and carrots get a heavier dose of manure and plenty of lime.

I grow legumes and curcubits in the final 2 beds:  I am sure to give compost or manure, seaweed, bone meal and lime to my curcubit/legume bed (which has squash and beans together) because the squash pretty much needs extra nitrogen earlier on that the beans cannot yet provide.  The other legumes (peas and favas) get seaweed, lime, bonemeal and a little well rotted manure if they’re lucky.  I do mulch well to keep them moist and provide organic matter to ensure healthy Rhizobium.  Thus, these beds are getting an extra dose of nutrients both during the season, and afterward when the legumes will leave their legacy.  Many of the minerals added from the seaweed and bonemeal will carry over for subsequent years too.  I am sure to plant a cover crop on this area to trap these nutrients in for the following year, or I plant winter greens or overwintered favas in November to prepare it for onions in the following summer.

So I guess technically, I have a 7 year rotation with 2 years of alliums broken up between 2 years at least of other things.  But the key thing here, is that I have heavy feeders (alliums), followed by lighter feeders, followed by legumes, followed by alliums again, so nutrients are managed to the best efficiency.  It’s not perfect, but that’s why I have compost as a mobile source of nutrient, so I can put an extra bit on the squash while leaving the rest, for instance.

Usually I automatically follow my legume beds with alliums so they get the benefit of those extra nutrients and so I am only really heavily feeding half of my garden in any one year.  I also avoid having sickly peas because I am prevented from planting them directly after alliums ever!

This also works for me because over the years I’ve learned that these groupings each take up roughly the same amount of space.  Like anything, crop rotation takes a bit of practice and planning.  Once you have lots of experience with your garden you’ll know what you like to grow and how much, and what doesn’t grow (you’ll notice I don’t grow potatoes, they bring out my black thumb!).

2011 Update:

We’ve just had a marvelous run of warm weather… so as long as your soil is workable, go ahead and plant your peas!  If you think of it, cover your plot with plastic for a couple days, then soak your seeds in time for weekend planting.  Here we go 2011!!

From 2010:

Well, finally it is safe to say, that frosty mornings are behind us… so this week I’m planting my peas.  Usually, if I haven’t done this by April it’s because I’m lazy, but we had such frosty nights this year, all the way through the long weekend!

I’m excited to announce that I will be at the Farmers’ Market in the Community Information booth this Saturday (April 17th) for the first outdoor market.  This is the booth near the bandstand, where Glen hangs out.  I’ll be handing out fliers and free tubers, and showing off my Comox Valley Urban Agriculture Resource Guide!  The resource guide is available for a suggested donation of $1.  I also have info on upcoming gardening workshops being held around the community, and there are many!

Peas are an excellent crop to grow in your garden, in fact, I think they would be my desert island crop- I would grow them over almost anything else.  Why?  Let me count the ways!

1.  They are early, and the whole plant is edible, so I plant extra and before the peas start blooming, I thin them out and put the green tips in salad.  This can be done a few times.  Amazing!  They are quite low maintenance, besides the trellising.  They are relatively tall, so weeding is easy.

2.  They are sooooo much better fresh out of the garden than they are from the store!! Someone once told me that within hours they loose half of their sugar and vitamin content- so they are a good choice to grow at home.  I have to say, that I never understood why some kids hated peas until I had store-bought snow peas for the first time.  They are packed with protein as well as vitamins A and C, folate and iron, but protein is so nice to have from your garden.

3.  They fix nitrogen in the soil, and leave the soil in excellent condition for late crops of greens, garlic or winter veggies.  They can be planted spring or summer, for fall harvest.  They are lovely to look at, covered in flowers with bluish foliage- very ornamental.  I could go on…

The tricky thing about deciding when to plant peas in the spring, is knowing how warm the soil is and that it’s not going to get cold and  stormy, and cool down before the seeds can germinate.  If you have some seeds in your soil like chickweed or pigweed, or radishes or orach (mountain spinach) and they begin sprouting, that’s usually a good indicator that it’s time.  Check the Environment Canada long range forecast for 5 days in a row with nights above freezing, 4°C or so.  Then at least they will have several days to germinate before another cold patch begins.

Along with peas, I usually also plant broad beans, radishes, arugula and spinach.  Everything, especially the spinach, gets a remay cloth or plastic tunnel cover for extra protection.  Wireworms and cutworms eat most of the spinach, but that’s ok.  It’s a good idea to pre-soak your seeds, especially for large seeds like peas or spinach, unless you have heavy, clay, wet soil.  This makes sure they can germinate evenly and don’t dry out during that time.  Let them soak at room temperature for 24 hours to 48 hours, changing the water every 12 hours or so if you can.

A few things to keep in mind with peas:

• They like a well-drained, slightly acidic soil, 6 or 6.5pH, and phosphate, so add a bit of lime and bone meal to the soil when planting.  Mature manure or compost is ok, but because they fix their own nitrogen, do not add nitrogen fertilizers or rich composts.
• You can plant them early, but since our soils tend to be cool, try preparing the bed and warming the area for a few days first with a plastic covering.  Don’t over-water.
• Keep the trellising in mind, plant in a row where the trellis won’t be in the way, or consider growing a dwarf variety to enable easier crop rotation if necessary.
• Dwarf varieties (such as Sugar Ann, Little Marvel or Dwarf Grey Sugar) produce over a shorter season, so do several plantings a few weeks apart.  Dwarf varieties are excellent for container growing if you have limited space!
• Sow them 2cm/1-inch deep, for later sowings (after mid April), sow deeper -4cm/2-inches deep, to protect from drying out.  Sow 2cm/1-inch apart or more, and thin as mentioned to no more than 4cm/2-inches apart.
• Do not try to plant after late April, until July or early august for a fall crop- soil is too warm and they will not thrive.
• They don’t like to grow where onions were recently.
• They can get quite tall depending on the variety, so take note of the height when you pick seeds, and if they are 3 feet or 1m tall  or more they will need trellising.  They will also shade other plants so keep them at the back of your garden.
• They will die back in heat, especially if your soil gets dry.  So watch out for watering if there’s a heat wave in May, because there’s no going back-you’ll have to rip them out if they start wilting and going yellow and wait until July or August to replant for fall.
• You may need to use garden legume inocculant, especially in a new garden.  This can be purchased from West Coast Seed, or most garden centres.   Email me if you have questions about this help@tgibc.org.
• We don’t generally have problems with pea enation virus in this area, but powdery mildew is a problem along with several soil-borne fungi – so pick a mildew resistant variety if possible, water in the morning if you can, keeping foliage dry, ensure they have good air flow, and practice crop rotation.  If we have a wet spring, cross your fingers.  If they are off to a good start and have good soil nutrition, they will continue to produce well with a mild mildew infection.

There are 3 main types, all with many names:

• ‘Snap peas’ aka ’sugar pod peas’ or ’sugar snap peas’ have a thick, juicy, sweet pod and sweet peas inside.  So, these are ‘edible pod’ peas.  Pick them when the peas are still small and tender, because as they mature, the peas eventually get hard and bitter and the pods toughen.  Those you can save for seed.  Varieties such as ‘Sugar Ann’ and Sugar Daddy’ are common.

• ‘Snow Peas’ aka ‘flat podded peas’ aka ‘Ho Lan Dow’, these are the flat, wide podded peas that are picked when the peas are still small, and the pods are tender and sweet.  These are the ones that are most often in Asian cuisine.  They are also an ‘edible pod’ pea.  Varieties include ‘Oregon Sugar’ and ‘Mammoth Melting Sugar’.

• ‘Shelling peas’ or ‘English peas’  are the ones that are grown for the peas only, and usually are stored for eating from the freezer.  They look somewhat like snow peas as the begin, but have a very tough pods and quickly begin filling with seeds.  The pods split open easily and peas are easy to harvest from them.  It’s a bit of an art to learn when to pick, and you will have to pick at least 2 times per week to get the best quality peas-even in maturity and nice and sweet.  If you’ve had canned peas, and compared them to frozen peas, perhaps you can begin to imagine what fresh shelled peas are like!  Popular varieties are ‘Green Arrow’ and ‘Alderman’ (aka ‘Tall Telephone’).

It was a rainy day at the boys and girls club. I have a small plot of land here that the B&G club kindly trade me for some mentoring while they get their education garden up and going. For some reason i decided to plant radish, a natural choice for an overcast day, but the the heavens opened and down came the rain. The intro part was easy, i had the aid of a nice shelter to stand under. Once i got outside, that was another thing altogether.

See me try to make it all work! The seeder, the camera, the seeds, and keeping it all dry. My goodness.

The Seeds. MMM delicious radish.

Well, spring has really sprung this time…at some point in the last 24 hours, the day became longer than the night.  I guess a few of you are starting to plan your gardens, I know I am!  So, what better time to start blogging about my garden for this Urban Aggie project.

I hope that If anyone else is reading this, they will send me questions to the Hotline rather than really use this as a guide…because everyone’s garden is different.  But I do plan to use this to let you all know what I am doing myself.   If you have questions, though, email me at help@tgibc.org. Please tell me what your soil is like, or your neighbourhood, what you’d like to grow, and how much sun you have.  I await your response!

For me and my veggie garden, spring means that peppers are seeded inside, and I’m beginning seed greens and broccoli for my coldframe.  Tomatoes and basil are next!

Also, since it was nice and dry and my sandy soil can be worked, I pre-soaked and planted my broad beans outdoors.  I can get away with this because my soil is very well-drained, and I have covered the row with plastic to warm the soil.   I did a  general garden clean-up and composted the spent winter veggies like the kale and long-dead chard at the same time.  The garlic is up and looking happy, and raspberries are starting, which is fantastic!

I also plan to lime this week, since I didn’t do that in fall. I’m just harvesting the last few burdock roots and kale leaves, and the parsley is coming back.  Time for soup!

I will soak and plant peas next, but not until until the beginning of April, so that ‘danger of frost has passed’ here in the Comox Valley.

It is still too early to plant out much of anything else that wireworms like until the wireworms have gone down in May.  I usually chance planting asian greens, arugula or cole crops first, since they are kinda mustardy, and the wireworms don’t like them as much as chickweed. Radishes are also a good bet.

Someone asked me if I would soon have lettuce plants at the farmers’ market, but I don’t start offering them until later in April.  Even then is early for it, unless I am trying to distract the wireworms from my peas!  I will have greens, but I leave planting my lettuce, spinach, carrots, potatoes and such til later.

The hardest part of this season is holding back- even though it’s nice out, our nights are still too cold for most greens to really grow, and wireworms are at their most destructive.  So without a coldframe it is still a month or so away from good planting weather.  I force myself to focus on all the amazing tomatoes and peppers I am starting instead!

Great News!

Spring is almost sprung, and we have begun!  I’ve created fliers to begin promoting the email hotline, and I’ll be handing them out at Seedy Saturday this weekend (March 6) at the Filberg Centre in Courtenay.  I’m so excited!  I’ll also be setting up drop-in session times in the next couple of weeks, so stay tuned.