Root knot nematodes

Nematodes that damage roots in the vege patch, are minute worm-like creatures, also known as eelworms. The female nematodes penetrate plant roots causing lumps to form on the roots, which affect the water-carrying ability of the roots. (These are not to be confused with the nitrogen–fixing lumps that form on the roots of legumes, see Fixing nitrogen). Root knot nematodes are more likely to occur in warm climates in soils that are low in organic matter, especially where a proper crop rotation has not been practiced.

Treatment
Each female nematode can lay up to 2000 eggs, and numbers can multiply quickly. Give affected plants a foliar feed of seaweed extract tea. Seaweed contains plenty of potassium that helps to strengthen cell walls and improves plants’ resistance to pests and promotes root growth. Remove all weeds. Some weeds are hosts to these pests and can transfer viruses to plants.
Affected plants must not be allowed to become water-stressed. Badly affected plants will have to be removed. Make sure the soil is damp so that soil clings to the roots. Place plants (with attached soil) into a garbage bag. Seal the bag, leave in hot sun for a few days, then place it in the garbage. Do not compost these plants. Once the crop is harvested, proceed with methods for prevention (see below).

Prevention
Allow 3 years between growing any member of the tomato/potato or melon/cucumber families in the same patch of soil. During this break, grow a green manure that is a ‘bio-fumigant’. ‘Bio-fumigants are green manures that release a gas that is toxic to nematodes. They are grown to knee height and chopped up and mixed through top soil, then covered with mulch. Green Harvest have seed for BQ Mulch (sown in cooler months) and cowpea (sown in warmer months) that control nematodes. Indian or brown mustard (Brassica juncea) and non-GM rapeseed (Brassica napus) are also effective bio-fumigants. Forget marigolds, they are more effective against northern hemisphere nematodes. During the 3 year break, brassicas or corn can be grown in the treated bed, if you have limited garden space.
When preparing beds, add a 5 cm layer of organic compost to the bed surface and cover it with organic mulch. Beneficial organisms in compost are pest nematode predators, and mulch keeps compost damp to allow microorganisms to work on restoring soil to health.

Greenpatch Organic Seeds

With some women it’s shoes or handbags, but with me it’s seeds, so I have to practice restraint when I go to Greenpatch Organic Seeds, as I did recently. Greenpatch supply a wide range of open-pollinated, organic seeds for vegetables, herbs, flowers, and grains, grasses and sprouts. You may have seen their seeds for sale at nurseries. Organic, open-pollinated seeds are not hybrids or GM seeds, and that means you will be able to save seeds from your crop for next season. Open-pollinated vegetable seed varieties are grown for flavour and vigour rather than shelf life.

Many of the seeds are produced at Greenpatch, but where cross-pollination can be a problem, other varieties are produced by local growers. I like buying organic seed that is produced in Australia because the seed comes from plants that have adapted to Australian soils and seasons. Previously, I had found that imported seed did not perform particularly well, and I achieved better results from seed I saved from those plants. We do save seeds from some of our crops but saving seed from all our vegetables and herbs can tie up garden beds for long periods while the seed matures, and being able to buy locally-produced seed makes life much easier.

Greenpatch also has a huge selection of fruiting plants, herbs, cottage garden and aquatic plants. Neville and Sophia have been producing seeds and plants on their farm for 20 years, and you can order seeds and plants by mail but, as Greenpatch is just off the freeway at Taree and only a short drive from our farm, I enjoy paying a visit and browsing through their stock for plants to add to our collection. You can see their catalogue at Greenpatch Organic Seeds.

Spring bulb reminder

When spring bulbs have finished flowering, don’t forget to allow the foliage to die back before lifting bulbs. It is important to leave the foliage because the yellowing and fading occurs as the plants withdraw nutrients from the leaves to store in the bulbs for next season’s growth. Depriving spring bulbs of this essential part of their growth cycle will result in poor, or no, flowering next spring.

Avoid digging near fruit trees

A reader has found that the soil around his fruit trees has become quite hard and has asked should he dig around the trees to loosen the soil.

It is not a good idea to dig around fruit trees as citrus, for example, have very shallow roots. Digging around these and stone fruit trees will damage roots and quite often cause suckers to grow from the root stock. Avocado trees deeply resent any root disturbance.

Hard soil can be a problem in extreme weather conditions, particularly if the soil has not been covered with mulch. If the area is weedy, cut off the weeds at ground level rather than pulling, or digging, them out. Plants obtain most of their energy for growth from light. As you are going to deprive them of light with this method, you can leave the roots to break down and add organic matter to the topsoil.
If grass has covered the area, cut it short and, with a sharp edged spade, cut through the runners 20 cm outside the ‘drip line’ of the tree, which is the area of soil directly below the outside edge of the foliage canopy of the tree – so called because it is where rain drips off the foliage canopy and the feeder roots of trees lie in this area.
Apply a light application of organic complete fertiliser to the soil surface in the drip line area and give the tree a thorough watering, but not close to the trunk. Immediately after watering, cover the soil surface beneath the tree out to the drip line with a 3 cm layer of compost, keeping the compost at least a hands width from the trunk. Compost contains microorganisms (and often earthworms) that will help break down the weed roots and make the soil more friable.
Then cover the compost with a 5 cm layer of organic mulch to keep compost damp and deter weed growth, keeping the mulch well clear of the trunk and extending it to 20 cm beyond the drip line of the tree. Don’t use compost as mulch, as it will dry out and you will lose most of its benefits.

Kid’s vege patch

Primary school children have opportunities to learn about sustainable gardening at school, including the Organic School Gardens program provided free to all Australian school students by Biological Farmers of Australia, but younger children can also have a lot of fun learning to grow their own fruits and vegetables.
Although they have a shorter attention span, very young children learn quickly when copying adults especially when they have a small patch of soil or some large pots for their own organic garden. International research has shown that children are more likely to enjoy eating vegetables that they have grown themselves, or helped to grow.

Vegetables that mature quickly or are miniatures are appealing to small children. Small lettuces such as heat-tolerant ‘Little Gem’ or ‘Mesclun Mixed’ and cherry tomatoes: “Tiny Tim’, ‘Tommy Toe’ or ‘Yellow Cherry Cocktail’ are fast-maturing. ‘Butter Bush’, ‘Provider’ and ‘Strike’ produce small pods of beans with good flavour. ‘Little Finger’ carrots mature quickly and ‘Bolthardy’, “Bull’s Blood’ or ‘Golden’ beetroot harvested as baby beets are rich in health-protecting antioxidants. ‘Golden Nugget’ is a small bush-type pumpkin and children enjoy digging for ‘chat’ potatoes in summer.

In cooler weather, ‘Di Cicco’ broccoli, ‘Snowball’ cauliflower, ‘Sugarsnap’ and ‘Oregan Snow’ peas, milder flavoured ‘Bloomsdale’ English spinach and baby leeks harvested when 2 cm thick can all be appealing to children.
Strawberries, melons and corn all take longer to mature but are popular with children. ‘Minnesota Midget’ rockmelon and ‘Sugarbaby’ watermelon are fast-maturing; ‘Golden Bantam’ sweet corn and ‘Golf Ball’ or ‘Ontos’ popcorn usually produce multiple cobs per plant. Corn is a whole grain, and organic popcorn is a popular and healthy snack food for kids. (See Growing popcorn)
Seed varieties mentioned above can by obtained from Eden Seeds or Greenpatch Organic Seeds.

Pumpkin problems

Karen has had disappointing results from her Queensland Blue pumpkin vine which produced pumpkins with very little flesh and she wants to know how to avoid problems in future.

Karen, if the seeds are soft and immature, you may have picked the pumpkins before the ‘fruit’ has fully developed, and pumpkins are fruits although we call them vegetables. However, if the seeds are mature, a common cause of this problem is hunger, and this can occur in several different ways even though you may have thought that the plant was well fertilised.

If soil is not damp, nutrients can’t be absorbed by the roots. If soil pH is too acidic or alkaline plants will go hungry because the soil pH controls which nutrients are available to plants, and pumpkins need a soil pH of 5.5-7 for good growth. Pumpkins vines can produce an enormous amount of foliage – and it is a huge task for the roots at the base of the vine to provide moisture and nutrients through the whole plant. When pumpkin vines are allowed to wander over soft earth, they will usually put down extra roots along the vines to assist with water and nutrient absorption.

You can encourage the formation of extra roots, see Assisting root growth.

Pumpkin flowers are pollinated by bees and occasionally a flower or flowers can be pollinated by pollen from a cattle pumpkin, which usually results in fruits that are tough and pretty tasteless. (If your neighbours are growing cattle pumpkins, you may have to hand-pollinate pumpkin flowers).

I’d advise you not to save any seeds from pumpkins that have little flesh or tough flesh as any vines grown from these seeds will probably produce poor quality crops. Only use seed from your best home produce or purchase seeds from a reputable supplier.

Pumpkins thrive on compost, so make compost through the winter ready for next season’s vines. Turning the heap a couple of times a week will keep you warm, keep the heap aerated, and speed up the composting process. If you live in a cool climate, put some black plastic over the top of the heap to help absorb heat. Use the compost to get your pumpkin vine off to a flying start in a different spot in your garden when soil warms in spring.

Growing potatoes update

A reader has asked if potatoes can be grown in the plastic tubs that are sold by Bunnings, Big W, etc., and I will answer it here as the links may be helpful to other readers.
Yes, Rebecca, they would be suitable if you add plenty of drainage holes and put several centimetres of gravel in the base of the tubs so that the potting mix does not block the drainage holes.
Opaque tubs provide similar conditions to small or medium drums (in that the young plants will be more shaded) and you should use those instructions for the tubs in this post. Basically the seed potatoes need at least 15-20 cm of potting mix underneath them and 15 cm of mix above them. Seed potatoes should be sown/planted 30 cm apart and, if they are the tubs I’m thinking of, you would probably only get one plant per tub as there is not really enough room for tubers of 2 plants to form.
The how and why of ‘hilling-up’ potato plants can be found in this post: Growing potatoes.

Advice on suitable soil conditions for the best results from potatoes can be found in Potato beds.
Also see: Other ways to grow potatoes.

Spinach

English spinach is an annual that loves cold weather. It is a fast growing, small plant that forms a rosette of green leaves and stems with a flavour more delicate than that of silverbeet.
It is a versatile vegetable that can be steamed or used in pies, quiches and soups, and is rich in folate, vitamins A, B6, C and E, as well as magnesium, iron and fibre.
In well-drained soil containing plenty of compost and a scattering of organic complete fertiliser, spinach plants are ready to harvest in 8 weeks. Sow seeds in pairs, 1 cm deep and 25 cm apart, directly where they are to grow, and seedlings should appear in 7 days. About a dozen plants are enough for the average family. Keep seedlings well-watered and give them a drink of half strength manure tea or organic liquid fertiliser about a fortnight apart until plants are well established.
When seedlings are about 5 cm tall, remove the weakest seedling of each pair, and use the well-washed thinnings in salads or soups. Where winters are long, progressive sowings can be made each month through winter. Don’t worry about sowing too many plants as English spinach freezes well. Blanch the washed leaves, pack them into ice cube trays with a little water, and freeze. Then transfer frozen cubes into a ziplock plastic bag for storage in the freezer.

This spinach is ‘Galilee’, a variant developed in the Middle East that is a lighter green and more tolerant of warmer winter temperatures – seeds available from Green Harvest.

Using wood ash

If you tend to accumulate wood ash from log fires over the colder months, you might be tempted to use it instead of lime to raise soil pH, as it contains between 45–50% calcium carbonate. It will certainly do that – but it should only be used on soils with a pH lower than 5.5 because the calcium in wood ash is in a highly soluble form that can change pH very quickly, and it is very easy to over-do the application. Ash from hardwoods contain one third more nutrients than ash from softwoods (e.g. pine).
Apply wood ash only to beds that are not going to be used for a while, using one handful per square metre. Test soil pH after 2 weeks to see if soil is in a more suitable pH range for plant growth. Wood ash should never be used near plants that prefer acid soils.
A safer way to use wood ash is to keep it in a covered container near your compost heap and dust it, instead of garden lime, between layers of other materials that you add to the compost heap. This will help to keep the compost heap sweet-smelling and ensure good microorganism activity. Mature compost holds nutrients in balance and compost containing wood ash can safely be applied to garden beds.
Wood ash can also be dusted over lawns that have become ‘sour’, especially where moss is growing. While the calcium improves the soil pH, the 2–8% potassium (potash) in wood ash will improve the lawn’s tolerance to heat and cold as well as improving disease resistant. However, if applying wood ash to lawns, avoid using seaweed fertiliser for the current season as seaweed also contains a considerable amount of potassium. Too much potassium can cause a magnesium deficiency.

Planting spring bulbs

The autumn equinox (when day and night are of equal length) occurred on Tuesday, March 20th, this year. Days are becoming shorter than nights now, and it is time to prepare soil for planting spring-flowering bulbs. These plants thrive in a compost-rich soil with some complete organic complete fertiliser added. Gardeners in Cool climates and New Zealand can plant bulbs now. However, as these bulbs grow better after a period of chilling, gardeners in warmer areas can put bulbs into the vegetable crisper of the fridge for about a month before planting.
Bulbs are normally planted at a depth twice the width of the bulb. In Warm climates, plant suitable bulbs up to twice as deep as indicated on the packet. After planting, mulch the area in early morning when the soil is cooler and keep the planted area just damp until growth appears. For moon planters, Full Moon phase is the best time to plant bulbs.