Strawberries: When And How To Thin To Renew Your Beds

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What a thrill it is to bite into a plump, ripe strawberry and know that the effort you have put into renovating your beds has paid off. For a small, home garden patch, all you need to do is set aside two afternoons and the work is done. 

Everbearing strawberries produce fruit in two flushes, either side of the heat of midsummer. If you live in Zone 8 or colder, you need to thin your beds out between 4 and 6 weeks after the last fruit, in fall. In milder climates, you can wait until late winter, when there is little else to do in the garden. Choose a mild day, when rain or snow is forecast. 

Your first step is to remove all of last season’s foliage, stems and runners, so that you can see the condition of the crowns. Dig up and discard old and infirm crowns and any that are surplus to requirements. Fill in the gaps with runners, crowns that were in the wrong place, or new plants. 

Next, you need to add compost, slow-release fertilizer, and water deeply to encourage root growth. Cover the bed with a layer of mulch, preferably straw, in order to protect the plants until the new foliage appears. 

When do you thin out strawberry beds?

Everbearing strawberries form buds, close to the crowns, twice a year, in summer and autumn. The summer buds produce flowers and fruit in autumn, and the autumn buds produce your spring crop. It is the autumn buds that need to be nurtured over the winter period in order for you to enjoy a bountiful spring harvest. 

Colder climates – Zone 8 and colder 

In colder climates, the plant starts its dormancy phase when the nighttime temperatures fall to around 20°F (-6°C). Renovating your plants when they are dormant reduces the amount of stress associated with the drastic action taken when thinning them out.

The window of opportunity for renovating your beds is during the dormancy period before temperatures fall below 10°F (-12°C). These low temperatures will cause permanent damage to the crowns of your plants if they are not protected. Last season’s foliage will not present enough of a barrier against frost and other damage. 

Warmer zones – 9 and above 

In Zone 9 and warmer, the strawberry plants will also enter a dormancy phase during the winter months. However, the foliage that remains on the plants will provide sufficient coverage of the crowns to prevent damage from the cold. 

Timing is not critical in this type of climate, but renovation needs to be done before the weather warms up and the new season’s growth begins. 

Weather on the day of renovation 

Choose a cool, calm, preferably overcast day, before snow or rain is due, to start the process. You do not want to stress your plants by trimming them harshly on a hot, sunny day. You also do not want the wind to frustrate your efforts to lay down a straw mulch.

Precipitation, shortly after renovation, will provide the added moisture your plants need in order to encourage root growth and will help to weigh down the mulch. It will also help to dilute any fertilizer you apply. 

If you are unable to complete the entire patch in one day, rather opt for completing the renovation process for the area that you can manage. If you leave the crowns exposed overnight, they may suffer damage from the cold. 

How to thin out your strawberry beds

Step 1 – Remove the foliage, stem and runners 

At the end of the harvest, your strawberry beds will be covered with foliage. The leaves are the kitchen of the strawberry plant, where sunlight is turned into food. They also provide shade for the roots and fruit, and to some extent, crowd out weeds. 

When growing everbearing strawberries, it is good practice to remove runners throughout the fruit-bearing phases of the plant. This concentrates the plant’s energy on the more mature crowns which are more likely to produce fruit. There will probably be a few rogue runners that you have not managed to cull.   

If feasible, you can use your lawnmower, with the blades set in the highest possible position, to remove the leaves, stems, and runners. I know, it sounds like a drastic action to take but it speeds up the process. 

Alternatively, if you have limitations such as raised beds, you can remove these using hedge clippers or secateurs. I leave between 2-3 inches of growth on each crown.

Set aside any runners that have an established root system. These may be needed for filling in gaps in the beds later on. Do not remove their leaves as this will cause unnecessary stress to the young plant.  

Step 2 – Check for weeds and pests, and test your soil 

During the defoliating stage, keep an eye out for pests on the plants, and nests or colonies that may have formed in the soil. Remove these and make note of what organic pesticides are needed.

Likewise, this is an opportunity for identifying and removing unwanted vegetation. Add the appropriate organic herbicide to your shopping list. 

Strawberries prefer a slightly acidic soil, around a 6.0 pH level. Now would be the time to determine what you need to add if the level is not correct. There are soil kits available for home users. Alternatively, you could send your soil away to be tested. 

You can correct the soil by adding heavily diluted vinegar directly to the soil. Longer-term solutions include adding pine needles or coffee grounds to your mulch and allowing the acids to leach into the soil with each rainfall and watering. 

Step 3 – Renovate the layout of your bed 

Strawberry plants are usually cultivated as perennials that last up to 5 years. If treated well, the plants will produce the maximum yield from the second to the fourth year. 

To keep your bed producing from year to year, you need to replace the plants that have reached the end of their productive lives. You also want to remove plants that are not healthy. 

Everbearing strawberries are planted, on a mound system, about a foot apart. The mound aids in the drainage of water and the spacing allows each plant to get enough light to produce the food it needs. 

For maximum yield, your plants should be planted on alternative sides of the ridge of a mound, at six-inch intervals, to form equilateral triangles, with sides approximately 12 inches long.  

After all the weeds, pests, and unwanted plant material have been removed, you should only have crowns left in the bed. Identify the younger and more robust crowns and remove the others. Also, remove any crowns that have established themselves outside the desired layout pattern. 

Now you should have an overall view of the layout of your bed. Fill in any gaps with the runners that you have rescued and any healthy crowns that were in the wrong place. 

Alternatively, if you wish to change the mix or ratio of cultivars in your bed, now would be the time to do so. Fill in the gaps with runners or new plants, according to your plan. 

Replenish the ridge of the mound in between your plants, with well-composted organic soil, taking care not to bury the crowns. If the roots are visible, their planting has been too shallow. The crowns should be ‘sitting’ on the ground. 

Step 4 – Fertilise and water 

Strawberry plants have several primary roots that can reach a depth of 4-6 inches. After renovating each bed, water it thoroughly in order to encourage these roots, which are attached directly to the crowns, to grow downward. If you water too little, they will stay at the surface and run the risk of drying out in the future.  

This is an opportunity to add a slow-release fertilizer that will see your plants through to the next spring when you will add nutrient supplements. 

Step 5 – Mulch the plants

Strawberries are so-called because they grow well in straw. If possible, add a 1-2 inch layer of wheat or other straw on top of your plants. This will serve as a blanket during the cold months, protecting the crowns from the damage caused by low temperatures. 

You can also check this article on strawberry mulching options if straw isn’t appealing or suitable for your climate.

In early spring, when the weather starts to warm up, gently rake the straw away from the crowns, allowing any new leaves access to light so that food production can begin.

Repeat this process as the plant grows, ultimately retaining enough straw to provide a resting place for the fruit. The mulch protects it from the moisture of the soil and prevents fungus from growing on the young strawberries. 

FAQs 

How does pruning my strawberry plants differ from thinning them out, i.e. the process described above?

Pruning should be carried out throughout the entire growing season, in order to remove unproductive leaves. For everbearing strawberries, you can also remove the runners that result from the main crowns. 

It is also thought that the size of a flower is indicative of the size of the strawberry it will become. Some people remove small flowers in order to conserve energy for plumper fruit. 

How does the renovation process differ for June bearing strawberries?

The renovation process is the same, however, the timing is different. June-bearing plants all produce their fruit at the same time. You would want to start the renovation process immediately after the last fruit has been picked for the season.