Zunckel Ecological + Environmental Services

Sustainable Decision-Making

Strawberry Towers

Conventionally, vertical gardens are becoming ever more popular as an alternative for gardeners who don’t have a lot of horizontal space, want to cover an unattractive wall, or just want something different. Living in a mistbelt, my motivation is different; the cool moist conditions are prime slug and snail habitat and I’m hoping that if I keep our strawberry fruit off the ground, they will stand a chance this year (see more on Strawberry Pest Control below).

Besides being an absolutely delicious fruit everybody in our family loves, strawberries are filled with vitamin C, fibre, iron, potassium and antioxidants so it’s really worth growing them.

Seeing as spring is around the time you should be planting your strawberries I thought it timely to write about this vertical strawberry planter we made a few months back in mid-June.

We’re testing out two simple options: strawberry plants planted horizontally in gutters and strawberry towers.

How to make a simple horizontal gutter strawberry planter

I was utterly inspired by this picture I found on Pinterest

I was utterly inspired by this picture I found on Pinterest

You will need lengths of gutter pipe cut to size with a hacksaw with stop end caps on each side. Drill small holes in the bottom of the guttering at approximately 20 – 30 cm intervals. Line the guttering with newspaper or geotextile and add a sprinkling of gravel. Choose a sunny well-ventilated spot. Fix the guttering to a wall or fence with gutter brackets or wire, as the case may be.

Add well prepared soil (see Strawberries Soil Preferences below) and plant your strawberries and companion plants using the instructions below.

This system lends itself well to a drip irrigation or aquaponics system which we will not go into here.

Here is the result of our Horizontal Gutter Strawberry Planters, just starting to get growing in the spring, wish CDs to scare off the birds.

Here is the result of our Horizontal Gutter Strawberry Planters, just starting to get growing in the spring, wish CDs to scare off the birds.

How to make a Vertical Strawberry Tower

There are various ways to make a vertical strawberry tower, from PVC downpipes to old gumboots to terracotta bought versions from your garden retailer. But we made ours using weldmesh fencing wire and black plastic sheeting.

Our daughter, Jessie's, Gumboot Strawberry Planter

Our daughter, Jessie’s, Gumboot Strawberry Planter

You will need:

  • Terracotta planting pots,
  • Weldmesh fencing wire, about 1.5m tall and as wide as the neck of your planting pot with a little extra for overlap. You don’t want it too tall because you won’t be able to reach up to water or too wide as it becomes top heavy and could tip over.
  • 100 micron black plastic sheeting to line the weldmesh.
  • A length of 50cm diameter PVC conduit for watering. Make it stand proud (about 8 – 10cm longer) than the wedlmesh. If you have a pressurised irrigation system, you can use a length of soak hose instead.
  • A drill to make holes in the conduit.
  • Geotextile to wrap the conduit.
  • Box tape or cable ties to secure the geotextile in place.
  • A cork.
  • Good fertile soil (see Strawberries Soil Preferences).
  • 1 litre or so of coarse gravel.
  • Strawberry and companion plants.

1. Cutting

Weldmesh & plastic vertical tower planter

TapingDecide on length of unit and cut the tower tube, plastic sheeting and watering tube accordingly, taking into consideration the height of the terracotta planting pot. Don’t forget to make the watering tube 8-10cm longer! We made ours roughly the height of the fencing posts at the gate to our chicken run which receives all day sun and lots of ventilation. Secure the plastic in place with box tape. Secure ends of the weldmesh in place up the height of the tower tube with cable ties or just bend the wire back on itself.

2. Drilling the watering tube

DrillingDrill vent holes in watering tube approximately 10-20 cm apart. Only drill these in the top 2/3 of the tube as the water will run down to the bottom plants. If you put holes all the way down the upper planter won’t get quite enough water as it will all rush out the lower holes. If you think you will do a good job of capping off the base end of the tube, you can put one small hole at the bottom so it doesn’t go anaerobic in there.

3. Completing the watering tube

Taping watering tubeThe Geotextile is to prevent roots and dirt getting into the watering tube and clogging it up. Cut the geotextile (we used scraps of winter sheeting) to the shape that can be bound tightly up the length of the pipe to cover the holes in the watering pipe and secure with cable ties or box tape (you don’t want this coming apart whilst adding soil to the tower). Then carefully with a knife, whittle down the cork until it fits the end of the watering tube really tightly.Cork

4. Strawberries Soil Preferences

Soil mixStrawberries prefer a slightly acidic soil with a pH between 5.3 and 6.5, but will grow in soils that have a slightly higher or lower pH level. They also need lots of organic compost. We mixed potting soil with soil, compost and shredded pine needles as our soil base.

5. Filling the Tower Tube

Place the terracotta planter in place against a wall or fence (a corner is best so the tube is less likely to fall over). Secure the weldmesh to the lip of the terracotta put with wire and twine. Fill the bottom 10 cm with coarse gravel and insert watering tube. Adding the well prepared soil (see Strawberries Soil Preferences) is a two-person job: one person to pour bucket loads of soil while the other holds the holds the watering tube in the centre of the planter. Compact the soil down as you fill. You may find it easier to fill soil only as high as the height you’re planting. Secure the tower once filled with wire to the wall, gate post or fence.

6. Planting

Carefully select the healthiest strawberry plants and try to choose hardy varieties. You should also trim off any older leaves from the plant and remove all flowers and runners. Roots should be trimmed so they are about 4 to 5 inches in length, and remove any damaged areas.

Strawberry planting depthCut a small (5cm) horizontal slit in the plastic between the weldmesh and carefully scratch a hole in the soil and lay the strawberry roots as deep into the soil as possible. Make sure that there are no air pockets and that the soil is nicely compacted around the roots. The plant should be placed in the soil so the midpoint of the crown is even with the soil’s surface and the roots fan out.

For the lowest hole we recommend planting a companion plant, which provides less incentive for pests to climb up. If you are using stoloniferous varieties (those strawberries that spread with runners along the surface) you can leave a few gaps in the lower holes. As the runners cascade down you can poke them into these vacant spaces. Make every 6th one a companion plant.

Beautiful sunset

Wonderful to be rewarded with such a beautiful sunset after a hard day’s work.

 

This is what our vertical strawberry towers look like now, after having been kept nice and warm by the black plastic through winter. They survived the frost and are starting to flower and fruit. Those that did not take were recently replaced with new strawberry plants.

This is what our vertical strawberry towers look like now, after having been kept nice and warm by the black plastic through winter. They survived the frost and are starting to flower and fruit. Those that did not take were recently replaced with new strawberry plants.

Maintenance of your Strawberry Plants

Water your strawberries well after planting especially in warmer weather and check daily. Vertical units do require vigilant watering. Water in the morning, so leaves are able to quickly dry. Water frequently until the plants take root. Then reduce watering to when the top inch is dry. Water is crucial for good fruit development.

For the first 6 weeks after planting, remove all blossoms on ever-bearing and day-neutral plants, by either pinching or cutting them. This will give them time to become established before expending energy towards growing fruit. Strawberries should be fertilised once a month, using an organic fertiliser. They can be sensitive to over feeding, so if you find you are experiencing excessive leaf growth and not much fruit, try fertilising less often.

Add mulch. The tower will continue to produce fruit for about 3 years. Make sure all plants in the towers get adequate light by rotating them, 6 to 8 hours of sun is required for fruit production.

After you have finished, fill the tower with potting soil and plant the remaining plants in the top of the basket.

Harvesting

Strawberries are ready to be picked as soon as the fruit has turned red. Of course, the exact shade of red that indicates ripeness depends on the variety of the strawberry. It is best to pick the fruit gently during dry weather, making sure that the green calyx (stalk) of the plant remains with the fruit. Strawberries can be stored for about 2 days in shallow trays in the refrigerator. For longer periods, it is best to freeze them.

Strawberry Pests

Slugs don’t like to crawl over copper. With some cleverness, one can come up with some really effective borders. A dozen or so pennies stuck onto the terracotta pot in a ring or into soil around a seedling can form a border. A stripped electrical cable is even better and cheaper. With some imagination a seedling or potting table can be very large and still only have 4 legs, with copper cable wound around them.

Strawberries are prone to both aphids and red spider mites. For either case, an organic insecticide needs to be used. Strawberries are also susceptible to developing powdery mildew and Verticillium wilt. If your strawberry plant has purple spots on the top surface of its leaves and white fungus on the bottom, it has developed powdery mildew and needs to be treated with an organic fungicide. Be sure to read the label carefully and follow all recommendations.

If you are noticing ants farming aphids on your strawberries, locate their path then smear some orange/citrus oil around the unit at this point. Stops them in their tacks!

A scarecrow is a good way to keep birds away from your strawberries. Use old CDs hung on strings which reflect light and scare the birds away. Also, try tying plastic grocery bags to stakes around your garden. The rustling sound scares the birds. Another deterrent is to paint stones and rocks red and place them around the strawberry plants, which will confuse and frustrate birds who can’t visually distinguish one from the other.

Companion Planting Strawberries

Strawberry plants are prolific, can be somewhat invasive, and most varieties will quickly form a thick matted row made up of strawberry runners if left alone. They hurt relatively few other plants (the exception will be discussed below) by being planted near them, but their rapidly expanding range can end up depleting nutrients or competing with other plants if they aren’t actively monitored.

Borage (Borago officinalis) is the magic bullet of companion planting and to learn more about its interaction with strawberries. Aside from borage, however, there are several other plants beneficial to strawberry plants. They are:

Bush Beans (Phaseolus) – The common bean is known benefactor of strawberry plants. It repels some beetles and hosts nitrogen-fixing bacteria which serve to fertilize the soil for better strawberry yields.

Caraway (Carum carvi) – Caraway is another herb that indirectly benefits strawberry plants by being nearby. The primary benefit of caraway is that it attracts parasitic wasps and parasitic flies that are voracious predators of many common strawberry pests.

Lupin (Lupinus) – This flower is actually a legume. Like the beans mentioned above, it also fixes nitrogen in the soil, thereby fertilizing for surrounding plants, including strawberries. It also attracts honeybees.

A simple defence against pests is to plant marigolds around the garden. The roots of a marigold release a chemical that kills nematodes. Also, planting several different kinds of herbs in your garden will keep pests from detecting the smell of the strawberry plants that attract them. Try planting mint, basil, lemon geraniums, garlic or onions for best results. Plant flowers to bring insects to your garden that prey on the pests such as ladybugs, spiders, lacewings and tiny parasitic wasps.

Not all plants will tolerate the presence of strawberries, however. The most notable garden plants that are harmed by the proximity of strawberry plants are those related to the cabbage.

Cabbage Family (Brassica oleracea) – Avoid planting strawberries near members of Brassica oleracea. The cabbage family plants will have their growth impaired by strawberry plants close by. The major members of the cabbage family include: broccoli, brussels sprouts, cabbage, Chinese cabbage, cauliflower, collard greens, kale, kohlrabi, and Romanesco broccoli.

Verticillium-Susceptible Species – The most common of these plants are tomatoes, potatoes, eggplant, and peppers, as they are all host to Verticillium wilt. If these plants (or melons, okra, mint, bush or bramble fruits, stone fruits, chrysanthemums, and roses) have been grown in the same spot recently (within 5 years), it is best to grow your strawberry plants elsewhere. Otherwise, the strawberry plants may be infected and die themselves. Crop rotation is key to helping to lessen the threat from Verticillium wilt.

References

How to Plant and Grow Strawberries in Containers by Darcy Logan Darcy http://www.doityourself.com/stry/growstrawberries#.U7BFdLFsL0s
Companion planting strawberries http://strawberryplants.org/2011/03/companion-planting-strawberries/
Keep Pests away from Fresh Strawberries Outside by Susan Patterson http://www.doityourself.com/stry/keep-pests-away-from-fresh-strawberries-outside
DIY Planters http://www.lovethispic.com/image/19384/diy-planters

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About Karen Zunckel

I have a passion for sustainability and love to share with others as I grow in knowledge myself. I make it my business to keep my finger on the pulse of who's 'green' in the KZN Midlands. By day I am an Environmentalist, Ecologist and Sustainability Consultant working from home where we are continuously trying to become more self-sufficient. I enjoy being creative and have started a community empowerment project making paper bead craft out of waste. Deep within my soul is a longing for wild places which I seek out as often as I can.

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This entry was posted on August 20, 2015 by in Food, Gardening, Sustainable Living and tagged , , , .
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