Crop rotation

Crop rotation is the practice of allowing a minimum of three years between growing a particular family or group of plants in the same patch of soil. This practice is essential to maintaining healthy soil because it prevents the build-up in soil of pathogens that cause soil-borne plant diseases. Plants weakened by diseases also attract pests. Many modern farmers have forgotten the importance of crop rotation. The trend is towards monoculture and these farmers have to rely on stronger and stronger chemicals in an effort to cure plant pest and disease problems.
There are eight main groups of plants that are commonly grown in vegetable gardens. Some groups can be grown together but others, such as legumes and the onion family, don’t make good neighbours.
If you find that pests and disease are repeatedly affecting your vegetables, and crops are disappointing, try the crop rotation below and you will find that your garden rewards your efforts. This rotation has six sections and includes a green manure grain, plus a legume green manure if you don’t want to grow your own peas and beans. The green manures are included because they recycle nutrients, replenish organic matter in topsoil, and help inhibit soil pathogens. In this rotation, legumes precede the tomato family because broad beans inhibit a fungal wilt that affects tomatoes. Organic matter assists in keeping soil healthy because it provides a habitat for beneficial microorganisms that keep disease organisms under control and improve soil structure.
Section 1:
Legumes – peas, beans, broad beans, or a green manure legume.
Section 2:
Solanaceous – Tomato, capsicum, chilli, eggplant, pepino, potato. (Some tomato family diseases can also affect Strawberries.)
Section 3:
Crucifers – broccoli, Brussels sprouts, cabbage, Chinese cabbage, cauliflower, horseradish, kale, kohlrabi, mizuna, mustards, radish, rocket, swede, turnip.
Section 4:
Green manure grain – such as barley, cereal rye, corn, millet, oats, sorghum, or wheat – depending on the season. Sweet corn can be grown in Section 4 if you have plenty of compost and don’t need to grow a green manure grain.
Section 5:
Chenopod family – silver beet, beetroot. (Winter spinach can follow a summer crop of beets as long as this group is not grown in the same bed for another 3 years.) Also the Aster group – lettuce, chicory, endive, globe artichoke, Jerusalem artichoke and sunflower.
Section 6:
Umbrelliferous – carrot, celery, coriander, dill, fennel, parsley, parsnip. Also the Allium family – all chives, garlic and onions.

Cucurbits – cucumber, gourd, marrow, pumpkin, rockmelon, squash, watermelon, zucchini. These, except for pumpkin, can be sown with group 5 or group 6, but not both. Pumpkins are best grown on their own because the vines are very vigorous and the roots give off compounds that can deter some other plants. Dill can also be grown with Section 3 to deter cabbage pests. Sweet corn is a good companion for cucumber or beans.

When the legumes are finished, group 2 can be planted in that bed. Group 3 replaces group 2 and so on, with all the groups moving up one bed. If you only have three or four beds, divide some of the beds proportionately, to suit your food preferences. Once your soil is restored to health, you can adjust the rotation to a three or four year one that suits the type of vegetables you prefer to grow, as long as you allow at least three years between the same group.
Crop rotation should also be practiced with flowering annuals and some perennials. Cinerarias and zinnias are related to the lettuce family, petunias are related to the tomato family, and stock and wallflower are crucifers. These plants can succumb to the same diseases that affect the vegetables in that group. Carnations and dianthus can be affected by a wilt disease if they are always planted in the same soil, and carnations, dahlias and irises can also suffer a stem rot disease if crop rotation is not practiced.

Manure tea

As it is Full Moon phase, later this week I will have to brew up some manure tea as a supplementary fertiliser for my lettuce, silverbeet, and spinach seedlings because they have a high nitrogen requirement. Manure tea can also be applied to flowering annuals, cabbage, celery, leeks, also Brussels sprouts that were planted out in February, or earlier.
I usually brew this up during Last Quarter phase as it only takes about a week in warm weather. As the weather has been much cooler than usual for April, the brew will take a good twelve to fourteen days to mature.
Manure tea gets its name from the fact it is applied to soil around plants at weak black tea strength, and around young seedlings as very weak black tea strength because strong fertiliser solutions can burn delicate roots. As it coats the foliage when applied to very small plants, I always water the seedlings after application because it is better to feed the soil than the plant.
Manure, and other fertiliser “teas” are easy to make. For this brew, I place a shovelful of horse manure into an old bucket, and fill the bucket with water. Then I cover the bucket with an old plastic tea tray. The cover prevents loss of nitrogen to the air, and flies laying eggs in the mixture, but a tight fitting lid will usually “pop” because of the gases formed as the manure ferments. The mixture should be stirred every couple of days, will be ready to use during New Moon phase. Sap flow in plants increases as the Moon is waxing, and New Moon and First Quarter are good phases to apply liquid fertiliser because they plants use them quickly.
I strain some of the brew through a piece of old pantihose into a watering can and add enough water to achieve the correct strength for the plants I want to fertilise. After fertilising, the bucket can be repeatedly topped up with water, and the brew can be used until it is quite pale. The residue can be added to the compost heap.
Always wear rubber gloves when handling manure fertilisers. They not only prevent smelly hands, they will prevent the manure coming into contact with any cuts or scratches on your hands.

Pumpkin update

Now that the pumpkin vine is dying off, we are able to find the entire crop – 27 pumpkins from one vine. Compost and plenty of water are the secrets to healthy pumpkin growth. Despite prolonged periods of rain, the vine has remained healthy without a hint of mildew because full access to nutrients has provided the vine with a healthy immune system. The only down side to this luxurious growth has been that it has provided a multitude of places for our chooks to hide their eggs.

Red leaves on citrus

Jane e-mailed: I have a question about my lemon tree. I bought a new one and planted it in a few weeks ago, and this week we have had a lot of rain. It has a fair bit of new growth, but the new leaves are red in some places. Is there something wrong with my tree?

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You have no reason to worry Jane, as you certainly have a healthy-looking tree.
Red colouring in new leaves is a common occurrence in plants that have adult leaves with a leathery texture, including avocado, citrus, eucalypts, oaks and roses. The colour is caused by the tree producing red anthocyanins (a type of antioxidant). These are believed to protect the young, tender leaves from ultra-violet light. The leaves will turn green as they toughen.
When citrus produce a lot of new growth as the weather cools, an application to the soil around the tree of seaweed extract at weak black tea strength will build the tree’s resistance to the effects of cold weather. Seaweed contains compounds that strengthen cell walls.

Slaters and earwigs

Slaters and earwigs feed on decomposing organic matter. If they are becoming a pest around your vegetables, you have probably added immature compost or uncomposted manures to your topsoil, or have a lot of semi-decayed organic matter in your soil. We get slaters in our compost heap but we don’t worry about them there as they are contributing to the composting process and dining in the heap keeps them away from the vege patch. Slaters and earwigs are attracted to stressed plants. Give your vege garden and any affected perennials a drink of seaweed extract tea (Acadia, Eco Cweed, or Natrakelp) at weak black tea strength. This will make plants more resistant to pest attack.

Slaters, which are not insects but related to prawns and lobsters, congregate in rotting timber, heaps of rotting vegetation, rock heaps, and shady, dark places. Remove breeding sites from the garden, and turn your compost heap regularly.
Someone told me that they are having great success drowning slaters in beer baits that I recommended in my book for snails and slugs. The slaters are attracted to the yeast smell of beer, as fermenting organic matter has a yeast smell (See post).
Jackie French recommends mixing one part pyrethrum powder to two parts plain flour, and placing baits in, or near, the dark places that slaters shelter in during the day. Try putting the baits in jar lids inside pots laid on their sides with loosely crumpled paper in the top to darken the interior.

Earwigs are slender insects with a set of pincers on the tail end of the body. They can be reddish-brown or black. These little pests will also feed on flower buds and fruit. They like to hide in confined areas in rocks, bark, timber and under debris. Earwigs can be trapped by putting crumpled newspaper into flower pots and leaving the pots on their side in garden beds. In the morning, drop the crumpled newspaper into a half bucket of soapy water to drown the insects, then refill the traps with fresh paper. Remove debris from around your garden to restrict their hiding places. If an earwig refuses to budge when disturbed, it is most likely protecting eggs laid in the soil beneath it. Dig down and dispose of the pale oval eggs.

Harvesting pumpkins

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It’s about time to harvest pumpkins again. Our pumpkin vine this year was a volunteer that sprang up in the chook run from the remnants of an old compost heap. It didn’t get any TLC because we half expected the chooks to trample it before it became established. However, it defied the odds and performed magnificently – which only goes to show how good compost is for growing vegetables.
I think it was only watered once but it received plenty of rain during its growing period, and the vine has produced at least 14 JAP pumpkins that we have found so far. JAP pumpkin is closely related to butternut pumpkin, gramma and trombone squash (Cucurbita moschata). These are thinner skinned and don’t keep as long as the Queensland Blue types (C. maxima).
Because we couldn’t spare the water last year, we bought all our pumpkins and some of them weren’t the best because of the drought. Consequently, we were curious to see what we could expect from our volunteer plant and picked one of the pumpkins early. (As you can see in the photo below, the stem is still moist.) Pumpkins picked at this stage do not keep well but we are using this pumpkin immediately, so it doesn’t matter. Now that they are nearly ripe, we will put a broken piece of foam box or thick cardboard under each fruit to keep them drier and clear of the ground, so they are less likely to rot. We will be leaving the rest of the crop until the vine dies off, and the stems become brittle, as that is when they develop their full flavour and store well. If you can’t wait that long, at least wait until the tendril closest to each pumpkin browns off.
Don’t worry about frost on your pumpkins, it will only kill the vines, and it is said that frost toughens the skins so that pumpkins keep longer.
P.S. When the vines had died back a bit, we realised that the vine had produced 28 pumpkins. Not bad for a volunteer vine! There were, of course, more than enough to supply family and friends, and we were able to sell the rest through our local organic greengrocer.
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Propagating Strawberries

In our area, propagating strawberries is usually a February job, but plants were late sending out runners this year due to the cooler summer. I like to use runners to grow some new plants each year, as vigorous, young strawberry plants are healthier and more productive. Once the new plants are growing well, I can thin out some of the older plants that are no longer performing well.
While our strawberry plants are fruiting, I put a plant marker next to the best producers. As soon as our strawberry plants finish fruiting and start to send out very long thin stems, I clear away the mulch to make it easier for the plants to take root. I then give the bed a drink of seaweed extract tea. Seaweed contains compounds that encourage root growth and build disease resistance.
At the end of each runner a small plant will form and tiny white roots will appear at the base (see photo A). Vigorous runners can produce two or three plantlets along each runner. I anchor plantlets from the best parent plants to the soil surface by placing a stone on the runner on the parent side of the plant. If the plantlet does not make good contact with soil, the roots will brown and the plantlet will die or grow poorly. Merely anchoring the plantlet to the soil surface allows the crown of the plant to sit on the soil surface where it should be. Strawberry crowns that become buried will rot.
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When the plantlet has produced a strong root system (see photo B), the runner connecting it to the parent plant can be severed with secateurs or a sharp knife.
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The new plant can then be left to grow where it is, or moved to another part of the bed so that all the plants have good air circulation. If I move new plants, I dig a wide shallow hole for each plant so that I can spread out the roots before covering them, and ensure that the crowns sit on the soil surface. I also remove all but one or two of the youngest leaves as this reduces any wilting after transplanting. I usually pot up some runners for spares too, just in case. Then, all that is required is regular watering and an occasional drink of manure tea until the plants are growing strongly. I don’t usually mulch them in autumn as the bare soil stays warmer and encourages the plants to produce plenty of healthy foliage so that next season’s berries will be hidden from birds.
Purists advise that runners should only be taken from plants that have not fruited because other plants are likely to be infected with strawberry virus. An aphid spreads this virus and we have never had aphids on our strawberry plants. As long as you use only runners from healthy, vigorous plants and use organic cultivation methods, there should not be a problem with runners that have fruited.

Garlic beds

It is still a bit too early to plant garlic in most areas, but not too early to prepare soil. Garlic needs a soil that is rich in humus but doesn’t require a lot of nitrogen so avoid adding manures to the bed. Uncomposted manures can cause garlic bulbs to rot, although processed poultry fertiliser is quite suitable for garlic. Garlic needs a full range of plant nutrients and trace elements for healthy growth. A drink of seaweed extract tea over the whole planting area will supply a full range of trace elements. Garlic also needs a soil pH of that is close to neutral. If you know that your soil is acid, give the bed a dose of dolomite or agricultural lime. Dissolve a generous handful in a full watering can and apply this to each square metre of the bed. Repeat again in a week or so for very acid soil.

Ladybirds

Ladybirds, except for the leaf-eating 26 or 28 spot ladybirds, are an asset to any garden. Both adults and larvae consume a considerable quantity of pests such as aphids and scale, and one type of ladybird feeds on fungus.
Most people know what adult ladybirds look like but ladybird larvae are strange looking creatures and many people confuse them with garden pests. As a result many of these hardworking pest predators are killed by pesticides, including organic sprays, and a decline in ladybird numbers is always followed by a pest outbreak. A common victim is the larvae of the Cottonycushion Scale ladybird which disguises it self so well, it is often mistaken for scale. A Brisbane web site has an excellent range of photos of ladybirds and their larvae. Check before you spray so that ladybirds won’t become an endangered species.
http://www.brisbaneinsects.com/brisbane_ladybirds/index.html

The cabbage family

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This family, called the Brassicas, tend to be more susceptible to attack from the Cabbage Moth and the Cabbage White Butterfly when conditions are too warm for them or when the soil they are growing in is too acid for their liking, especially while the plants are young.
The cabbage family includes Brussels sprouts, Chinese cabbage, cauliflower, horseradish, kale, kohlrabi, mizuna, mustard greens, swede, tatsoi, turnip, watercress and stock, and is also related to radish. These plants need both boron and molybdenum for healthy growth and these are only available to plants when the soil pH is close to neutral. If you know that your soil is acid, and your Brassica plants are being attacked, give the bed a drink of dolomite or agricultural lime. Dissolve a generous handful in a full watering can and apply this to each square metre of the bed. Repeat the application if pests are still hanging around in two weeks.
In the meantime, remove all pest eggs from under leaves and leave crushed caterpillars on the leaves. This helps to deter further egg laying.