Presentation #3 – Garden Methods – Crop Rotation
If your head is spinning around about what to plant where in your garden, the concept of rotation will help.
Rotating crops, that is.
Rotation is also very important to the health of your garden plants and soil.
What is “Crop Rotation”?
Rotation means not planting the same kind of thing in the same spot every year (as far as annual crops), based on their botanical families.
(Refer to the garden-oriented botanical families chart at the end of this blog post)
The #1 rule of crop rotation is: whatever plant family was planted in a spot one year, don't plant another member of that family in the same spot the next year. Choose something from another botanical family (more on that later). You can rotate plant families to different garden beds, sections of beds, rows, or containers.
Certain plant families have a stronger effect on soil, nutrients, and other factors, for better or for worse. These include:
Brassicaceae
Cucurbitaceae
Fabaceae (Legumes)
Solanaceae
Poaceae
Apiaceae
Liliaceae
Why use Crop Rotation??
Why is it important to rotate the planting of plant families through the garden?
There are both positives and negatives.
Insect Pests
The eggs and larvae of some insect pests reside in the soil. If, say, you planted cabbage in plot A, a pest of that Brassica crop could still be there the next year. If you plant another member of the Brassicaceae in plot A next year (such as, say, broccoli), those pests have a ready source of food! It's better to confuse them by planting something from a different family, especially one that the pest doesn't like or can't eat, than to welcome it with a Brassicaceae Buffet.
Plant Diseases
“ … plants release toxins that over a period of time can build up in the soil to a level severely stunting or even killing” the plant (Hunt and Bortz, p. 66). This is called “autoallelopathy”. Likewise, there can be a buildup of harmful soil organisms, such as certain species of fungi. This will carry over to the next crop if the next is in the same family as the previous crop. This can spread from one plant to another. You can interrupt this cycle by following with a crop from a different family.
Growth Enhancement
Conversely, plants can leave behind certain chemicals that “can have a positive growth-enhancing impact” on successive plants of another family (Hunt and Bortz, p 66).
Nutrients
- Some plant families (like the Brassicas) are “heavy feeders”. It is important to precede and follow them with a crop that supplies more nutrition (this can also be a cover crop, which we will cover elsewhere). Or, you can add more compost to get the soil going again by feeding the microorganisms in it.
- Plants of some families adds certain nutrients to the soil. A classic example is the family Fabacea (legumes), which can fix nitrogen from the air and make it available in the soil for other plants (after the legume plant dies, the nitrogen is released). You can follow legumes with heavy-feeding crops or anything that benefits from more nitrogen, such as corn or greens.
- Be aware that, though most plants like a more neutral range in soil pH, some do better with either more acidic or more alkaline soil. Potatoes prefer more acidic soil than most common vegetables, so try not to follow them with something that needs alkaline soil, unless you balance the pH by adding organic matter.
- When planning your crop rotations, be aware of what nutrients certain plant family crops need from or add to the soil.
Soil Texture
Plants can have a strong effect on soil texture. Some, like legumes, are “soil builders”. Plants with long tap roots (carrots, parsnips, long radishes, etc.) can “mine” deeper soil for nutrients and trace minerals to bring up closer to the surface. They also can help break subsoil and provide more pockets in the soil for air and water. Farmers are using daikon radishes (a very deep-rooted, white Japanese radish) as a cover crop for this purpose, between other crops.
As another plus, you can choose to alternate a spot between above- and below-ground crops to affect soil texture and also to thwart soil-dwelling pests and diseases that feed on root crops.
These are all considerations for crop rotation plans. But, it doesn't have to be complex. Start simple!! Mainly, remember not to follow a crop with another that is in the same family (refer to the botanical families chart at the end of this blog post).
(Quotes taken from: High-Yield Gardening: How to get more from your garden space and more from your gardening season; Marjorie B. Hunt and Brenda Bortz; Rodale Press, Inc.; 1986)
Farming has often been done in a basic, 2-year rotation schedule – corn one year, soybeans the next, then corn again the next year, etc. The soybeans help condition the soil and add nitrogen for the next year's corn.
Increasingly, more farmers are adding a third factor into the rotation – cover crops. These are various types of crops (such as rye, daikon radishes, turnips, rape/mustard, oats, clover, etc., or a mix) that help cover and protect the soil, decreasing loss of nutrients via erosion. They also add nutrients to the soil and improve soil texture.
Photo credit: Edwin Remsburg and USDA-SARE
(Sustainable Agriculture Research and Education/US Department of Agriculture: SARE.org )
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What is a Gardener to do with Crop Rotation?
(Especially a beginning gardener?)
Keep It Simple!!
Start with a 2-year rotation plan, then go on to others (3- or 4-year) gradually, as you learn to use rotation and see how it works with the kinds of crops you want to grow.
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Starting With a 2-Year Crop Rotation Plan
A simple way to do this is to rotate between a legume crop and another crop family.
And on and on, each year alternating the legume crop with something else.
>> Instead of cabbage, broccoli, tomatoes, peppers, etc., you could alternate the legume crop now and then with a root crop (beets, carrots, radishes, turnips, etc.) to condition the soil, if needed. <<
Remember that the same can be done with container plants, if you are seldom changing the soil.
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After you have done a 2-year rotation plan for some time and feel you have the hang of it, you could move on to a ...
3-Year Crop Rotation Plan
Add in a cover crop!
Yes, we can do that in gardens, too!
Here's an example:
Then, add in beans the next year again. The cover crop in this example is Oats (year 2), but others can be used. Cover crops will be covered more specifically sometime in the future in another blog post.
… Or, you could do the above-ground/below-ground crop rotation for a 3-year cycle:
This helps condition soil and bring up nutrients from further below. And, rotating root crops with above-ground crops (those with shallower, fibrous root systems) helps to confuse underground pests that attack root crops, such as root nematodes and wireworms (larvae of Click Beetles).
Remember to Keep It Simple.
I'm showing various kinds of crops as examples – maybe some of those are ones you'd like to grow, or you'd like to grow something else from the same plant families.
Here's another simple 3-year rotation plan, alternating these families in a plot:
Fabaceae (legume) > Solanaceae > Cucurbitaceae.
(refer to botanical families chart at the end of the blog post for crop examples)
Let's plug in some popular crop family examples for plot A:
Year 1: beans Year 2: tomatoes Year 3: cucumbers
Choose to grow what your household will use and work those into a 2- or 3-year crop rotation plan.
Make a list of what you want to grow, and keep plant family members together in the list.
Just remember:
Don't follow one botanical family member with another of the same family.
Include soil conditioners when needed (legumes, roots, cover crops)
Add organic matter to the soil.
These three things are all you really need to do.
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But, once you have enough experience and feel confident and practiced enough, you may want to try:
4-Year Crop Rotation
Why do 4 or more years?
For some crops, such as Brassicas, it is recommended to have a three-year lapse before planting something of that family in that spot again, in order to control the pests and diseases that may plague them.
Here's a general example, for one plot:
Year 1: Brassicas/Mustard Family (examples: cabbage, broccoli, cauliflower, kale, mustard, Brussels sprouts, turnips).
Year 2: Solans/Nightshade Family (examples: tomato, potato, pepper, eggplant) - OR -
Cucurbits/Gourd Family (examples: squash, pumpkin, cucumbers, gourd, melon).
Year 3: Lily Family (examples: onion, garlic, leek, shallot, scallion).
Year 4: Fabaceae/Legume Family (examples: beans, peas, peanuts, limas, cowpeas).
You can choose to reintroduce a Brassica crop in Year 4 or 5.
>> Bonus: some of those families can be used as a cover crop, also:
For the above example –
Year 1 (Brassica): radish, turnip
Year 4 (Legume): cowpeas, vetch, alfalfa
Here's another example of a 4-year rotation (again, looking at just one plot):
Year 1: legumes
Year 2: brassicas
Year 3: root crop (but not those from the Brassica family)
Year 4: leafy greens (but not those from the Brassica family)
Play with these and see what works for you!
(there is a Practice Exercise coming up! )
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In future presentations/blog posts, we'll get into more planting methods you can incorporate (companion planting, inter-planting, succession planting) that help with pest control, nutrients, pollinators, economic use of space, etc. Incorporate those as you feel ready!!
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IMPORTANT!!
KEEP GOOD RECORDS!!!
It can be so easy to forget what you have done year-to-year!
You could do this in the form of a garden journal, or with just simple record-keeping.
Having schematic garden “maps” is essential.
Here are types of information to include:
Varieties planted (include plant families)
When they were planted (as seeds or transplants)
Where you planted them
Expected days to harvest
When you started harvesting from each kind of crop
Observations throughout the season: pests (and other critters), diseases, other damage, growth, quality of harvest, etc.
Temperature, precipitation, weather events that affected or could have affected your crops
Drawings (maps) of each plot, row, or container planted
When (if) you added compost, manure, or other soil amendments, and mulch
At the end of the garden year, your notes and drawings will provide you with much information that you can use for the future. You can make up your own journal/planner or buy one, or explore examples on line (see references at the end).
** Mainly, this will help you keep track of your crop rotations – what you planted where, and when. Over time, you can see how your rotation plan has worked! **
And Now (drum roll ….. )
A Practice Exercise!!!
First, make a list of crops you would like to grow (remembering what your household would really use, and to Keep It Simple).List them with their botanical families.
(refer to plant families chart at the end of the blog post)
Now, pretend that you have marked out a simple 4' x 4' square for a new garden bed (or, that you have built a 4' x 4' raised bed and filled it with good soil). Draw this out. Graph paper can be useful.
Next, divide that into 2' x 2' spaces. Number the spaces 1-4, clockwise around the plot, starting in the upper left.
Then, do another one, and do the same numbering of spaces 1-4. You are going to practice doing a simple rotation with four spaces in a bed, so each drawing will be a different year. Label them Year 1 and Year 2.
Now, with a pencil and your plants list, play around with a 2-year rotation plan. Start with just the Year 1 block. Jot down what kind of crop you'd like to grow in each space, each one from a different botanical family.
Example:
To keep things simple, in the Year 2 squares jot down the same crops, but rotate them all to the next squares, counter-clockwise.
Example:
Now, if you made two more plot drawings like these, representing Year 3 and Year 4, and kept rotating these crops to the next squares – well, you have a simple 4-year rotation!!!
Further practice:
Try keeping the same plant families in the same order as before, but substitute other kinds of crops in those families that you'd like to grow.
(For example: broccoli, peppers, leeks, peas)
Try doing the same, but using a cover crop for of the families, in the second year.
(For example: Year 2: cowpeas, cabbage, tomatoes, onions, OR: beans, daikon radish, tomatoes, onions)
Try using some other families in your rotation than you did in your original example. Try changing just one family first, then try more.
(For example: cabbage (Brass.), cucumbers (Cucurbit), onions, beans. Or: lettuce (Asteraceae), cucumbers, onions, beans.
Try doing a rotation that includes both above-ground and below-ground crops.
(For example: Year 1: cabbage, tomatoes, carrots, beans; Year 2: bean, radish, tomato, lettuce.
I've been using basic square plot examples, similar to Square Foot Gardening. But, rotations are adaptable to any other garden design shown in previous presentations: rows, wide rows, various bed shapes, incorporating verticals, and container gardens.
Now, look at the plans you have already been working on for your prospective garden, from the very first Grow City workshop on (the ones started on graph paper).
Use your “wish list” that you came up with at the end of the “Garden Methods” presentation/blog post.
Take what you have learned from this Crop Rotation presentation and use it in your plan!
And, be sure to share your plans with us at Grow City Teaching Garden, on the Facebook page or via email!
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And, now (another drum roll ... )
That long-awaited botanical families chart I kept referring to!! This would be a really good one to copy and paste (and print out) into your record-keeping, for reference. After that, I'll include a list of Garden Planners to investigate – find what works for you or use them as inspiration to create your own.
Botanical Families Commonly Used in Food Gardens
Family names and descriptions, and garden plant examples:
Brassicaceae – sharp, peppery flavor, 4-petaled flowers, seed pods are siliques or silicles
Broccoli, cabbage, Brussels Sprout, Cauliflower, Kale, Radish, Turnip, Collard, Mizuna, Mustard, Arugula, Komatsuna, Kohlrabi, Bok Choy, Rutabaga, Horse-radish.
Hearty feeders – precede with legumes
Cucurbitaceae – mostly native to temperate or tropical areas, crawling or climbing vines, tendrils, flowers 5-petaled (petals fused together), many flattened seeds and tough rind.
Cucumber, Melon, Squash, Pumpkin, Watermelon, Luffa
Precede with winter rye or wheat, follow with legume.
Poaceae (Grass Family) – wind-pollinated, parallel veins on leaves, a cylindrical sheath wraps around the stem with the blade (leaf) above, node where the base of the leaf attaches, flower/seed heads are spikelets.
Wheat, Oat, Rye, Corn, Sorghum, Barley, Millet
Plant before Solanaceae or Cucurbitaceae. Good for controlling weeds, and as a cover crop.
Fabaceae (Legumes) – one-chambered seed pods that split open on two sides.
All Beans, Pea, Soybean, Lentil, Lima, Peanut, Chickpea, Clover, Vetch, Alfalfa
Beneficial to soil (fixes nitrogen from air) – good before or after heavy-feeders and plants that need more nitrogen. Some used as cover crop.
Liliaceae (mainly Alliums) – showy flowers with parts in 3's, parallel veins in leaves.
Onion, Garlic, Shallot, Leek, Chive
Good to rotate with legumes.
(Note: Asparagus used to be classified in this family, but has been reclassified into Asparagaceae).
Solanaceae (Nightshade Family) – flowers have five united petals, stamens fused in the center in a cone shape.
Tomato, Pepper, Eggplant, Tomatillo, Potato, Ground Cherry, Husk Tomato
Heavy feeders – precede with cereal grain or grass, follow with legumes.
Apiaceae – tiny flowers grouped in compound umbels (umbrella form), stems of the flower cluster radiate from a common point, stems usually hollow between nodes, petioles along the stem have sheathing bases, aromatic.
Carrot, Celery, Celeriac, ,Parsnip. Many herbs: Coriander/Cilantro, Fennel, Chervil, Dill, Parsley, Angelica, Caraway, Anise, Cumin.
Follow with legumes or heavy mulch.
Lamiaceae (Mint Family) – square stems (in cross-section), leaves arranged opposite each other along stem, flowers 2-lipped and tubular, plant aromatic.
All Mints, Oregano, Basil, Lemon Balm, Catnip, Thyme, Sage, Lavender, Salvia, Marjoram, Savory, Rosemary
Many are good companion plants and attract pollinators.
Asteraceae (Aster/Sunflower Family) – many tiny true flowers aggregated together in a flower head (composite form), some flower heads have showy, sterile petals around the edge.
Sunflower, Lettuce, Cardoon, Artichoke, Jerusalem Artichoke (Sun Root), Calendula, Endive, Chamomile, Salsify, Tarragon, Escarole, Bee Balm/Bergamot, Marigold, Zinnia, Chicory/Radicchio.
Very good for attracting pollinators.
Amaranthaceae – weedy plants lacking obvious flowers, globby or poky seeds along stems
Beet, Swiss Chard, Spinach, Amaranth, Quinoa, Orach
(includes the sub-family Chenopodiaceae, which used to be a separate family called Goosefoot)
Polygoneaceae (Knotweed/Buckwheat Family) - Leaf-like sheaths around stem just above where
leaf blade attaches to stem, swellings at nodes, clusters of small, knobby flowers, usually pink
or white.
Buckwheat, Rhubarb, Sorrel
Buckwheat is a good summer cover crop.
Malvaceae (Mallows) – leaves arranged alternately on stem, a stipule on the stem below each leaf. Showy petals.
Okra, all Mallows (including Marsh Mallow), Hibiscus, Cotton
Convolvulaceae (Morning Glory Family) – twining vines, showy flowers with fused petals.
Caprifoliaceae (Honeysuckle Family) - leaves oppositely arranged on stem, aromatic plant.
Corn Salad/Mache, Valerian
Garden Planners
SouthernExposure.com/gardenplanner
try free for a week/can subscribe for $29/year. On-line tool throughout the year.
Thespruce.com/free-garden-planners-1357749
11 Free Garden Planners and Programs
Gardeners.com/how-to/kitchen-garden-planner/kgp_home.htm
Kitchen Garden Planner – Gardener's Supply Company
using Square-Foot Garden techniques to create a raised bed garden.
Gardenandhappy.com/free-garden-planners
10 of the Best Free Garden Planners Available Online
Motherearthnews.com/garden-planner/vegetable-garden-planner
Clydesvegetableplantingchart.com
How to buy it (also available through Baker Creek Heirloom Seeds)
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