Knowing your climate zone will help you decide the best time to sow the vegetables, herbs and flowers you want to grow, and which varieties should perform well in your garden. Growing plants that are suited to your climate zone will usually give you the best results in your garden.
Purposefully ripping up healthy young plants may seem a strange and destructive thing to do, especially if theyve come from seeds youve sown yourself. But for many plant species its an essential part of successful cultivation. The process is known as thinning or thinning out, and heres why its so important.
Thinning seedlings is a crucial task for any gardener growing plants from seed But what exactly does it mean to thin seedlings? This comprehensive guide will explain everything you need to know about this important gardening practice
What is Thinning Seedlings?
Thinning seedlings simply refers to removing some young seedlings that are growing too close together. It involves cutting off or pulling out the weaker, smaller seedlings to leave only the strongest seedling in a group.
The main reasons for thinning seedlings are
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To prevent overcrowding. Seedlings growing too close together will compete for light, nutrients and space. This leads to spindly, weak growth.
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To achieve proper spacing for healthy growth. Plants need adequate space to develop robust root systems and foliage. Proper thinning ensures proper spacing.
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To allow good air circulation around plants. Crowding causes poor air circulation which can encourage fungal diseases.
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To allow each plant sufficient access to sunlight. Crowded seedlings will be etiolated and leggy as they reach for light.
When to Thin Seedlings
Timing is important when thinning to minimize stress to seedlings. Here are some guidelines:
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Indoors: Thin excess seedlings once they develop 1-2 sets of true leaves. This prevents tangled roots.
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Outdoors: Thin once seedlings are 2-4 inches tall and have 2-3 sets of true leaves. Earlier thinning risks disturbing roots.
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Avoid hot afternoon sun when thinning. Morning or evening is ideal to reduce transplant shock.
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Thin plants with sensitive roots like beans and cucurbits quickly before roots intertwine.
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Wait until soil is moist. Thinning in dry soil can damage remaining seedling roots.
The takeaway is to thin seedlings once they are established but before they become overcrowded.
How to Thin Seedlings
Thinning seedlings is easy to do using the following steps:
1. Decide Which Seedlings to Remove
Scan the group and choose the largest, healthiest looking seedling to remain. Remove weaker, spindly seedlings surrounding it.
2. Use Small Snips for Precision
Avoid tugging seedlings out which can disturb roots. Instead, use micro-tip snips to cleanly cut off unwanted seedlings at soil level.
3. Space Remaining Seedlings Appropriately
Consult seed packet for recommended spacing. Gradually thin to proper spacing over a few weeks.
4. Water Thinned Seedlings
Water thoroughly after thinning to minimize transplant shock. Consider using compost tea to give them a nutrient boost.
Follow these simple steps carefully to successfully thin your seedlings. It may seem harsh at first, but is vital for healthy, productive plants.
Which Plants Typically Require Thinning?
While thinning improves growth for all crowded seedlings, some plants really depend on proper thinning for best results:
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Root crops – Carrots, radishes, beets need wide spacing for straight roots.
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Leafy greens – Lettuce, spinach, kale quickly become overcrowded.
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Vine crops – Cucumbers, melons, squash require room to sprawl.
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Large plants – Tomatoes, broccoli, peppers need space to mature.
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Flowers – Marigolds, zinnias grow and bloom best when thinned.
When in doubt, refer to the seed packet for recommendations on thinning and spacing needs.
Can You Transplant Thinned Seedlings?
Gardeners often ask if it’s possible to save thinned seedlings by transplanting them elsewhere rather than discarding them. This can be risky, but is possible using great care.
Some tips for transplanting thinned seedlings:
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Start with larger, more established seedlings. Young starts are fragile.
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Gently loosen the soil around roots before lifting. Try to keep some soil around roots.
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Move quickly and replant right away to minimize root damage.
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Water transplants frequently for the first week until they recover.
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Not all plants can tolerate transplanting. Focus efforts on resilient veggies like tomatoes.
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Accept that thinning is easier and some transplants will fail. It’s not worth losing everything.
While it takes patience and care, transplanting thinned seedlings can sometimes work, saving you from wasting seeds and plants.
Common Thinning Seedling Mistakes to Avoid
Thinning crowded seedlings is simple, but beginner gardeners often make these mistakes:
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Thinning too early before seedlings are established. Wait for 1-2 true leaves.
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Thinning too late once plants are suffering from crowding. Don’t wait for leggy growth.
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Pulling seedlings out rather than cutting at soil level. This disturbs roots of keepers.
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Not thinning to proper spacing. Ignore seed packet guidelines at your peril.
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Thinning in hot midday sun or dry soil. Time it for cooler part of day when soil is moist.
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Transplanting thinned seedlings improperly. Seedling roots are delicate so take great care.
Avoid these common errors, and your seedlings will thank you for proper thinning care!
Thinning Alternatives to Minimize Waste
For gardeners who hate destroying seedlings, here are two alternatives that can reduce thinning:
Precision Seeding
Carefully space seeds further apart when sowing to minimize overcrowding that requires thinning. This takes more time but can work for larger seeds.
Edible Thinnings
Harvest thinned seedlings for salads rather than composting. Many leafy greens, herbs, and root crops can be eaten when very young.
While thinning is still required for best growth, these methods allow you to get more out of your thinned seedlings.
Thinning seedlings is the process of selectively removing some young plants to reduce crowding and improve growing conditions. Proper thinning results in healthy, productive plants that grow to their full potential.
While it may seem heartbreaking at first to cut off perfectly viable seedlings, remembering the benefits to the remaining plants makes the task easier. With the right technique and proper timing, thinning is a simple way to ensure your plants thrive.
Follow the guidelines in this article, and your seedlings will flourish thanks to your careful thinning efforts. Your garden will reap the rewards through robust, bountiful plants.
How to Use Climate Zones
First, find your climate zone using the map or descriptions below. Next, refer to our sowing chart, which provides approximate sowing times for our most popular seeds for each climate zone.
While knowing your climate zone is helpful when planning your garden, there are many other factors that may affect how your plants grow, including unseasonal weather conditions, the specific microclimate of your garden and how you care for your plants. You know your garden better than us, so if a different climate zone seems to ‘fit’ your garden better, go ahead and use it as a guide.
Our climate zones cover huge areas of Australia, so we recommend gardeners also consider their local conditions when planning what and when to plant. For example, gardeners in alpine areas have shorter growing seasons than gardeners in cool coastal areas, even though both alpine and coastal areas are included in our ‘Cool Temperate’ climate zone. We recommend gardeners in cool regions look at the ‘days to maturity’ information provided for each variety and choose those that will mature in a short (6-12 week) growing season.
- Includes: Darwin, Cairns, Townsville, Exmouth
- High humidity summers with most rainfall in summer and dry, warm winters. Includes northern Australia from Exmouth (WA) across to south of Townsville (Qld).
- Set as my climate My climate
- Includes: Alice Springs, Mildura, Albury-Wodonga, Shepparton, Wagga Wagga, Dubbo
- Hot dry summers, winters can be warm or cool depending on the region. Includes a large area of central Australia from the WA coast to Charleville (Qld), Tamworth (NSW) and Albury-Wodonga (NSW/Vic).
- Set as my climate My climate
- Includes: Brisbane, Bundaberg, Coffs Harbour, Gold Coast, Hervey Bay, Mackay, Rockhampton, Sunshine Coast
- Warm humid summers with high summer rainfall and mild winters. Includes coastal Queensland and northern NSW from north of Mackay to just south of Coffs Harbour.
- Set as my climate My climate
- Includes: Sydney, Perth, Adelaide, Newcastle, Toowoomba, Central Coast NSW, Wollongong, Bunbury
- Moderate humidity and reliable rainfall, with four distinct seasons. Includes coastal areas from north of Port Macquarie to south of Woollongong in NSW, coastal SA and the southeastern coast of WA.
- Set as my climate My climate
- Includes: Melbourne, Canberra, Hobart, Launceston, Ballarat, Bendigo, Geelong, Mt Gambier
- Low humidity with most rainfall in winter; hot dry summers and cold winters. Some regions will experience frosts and snow. Includes coastal areas of south-eastern Australia and alpine areas of Victoria, NSW and Tasmania.
- Set as my climate My climate
What if I can’t find my climate zone? If you can’t locate your zone from looking at the map or the descriptions on this page, we suggest that you think of an area that has a climate that’s similar to yours and use the zone for that area as a guide.
What if I live on the border of two zones? If you live near the border between two zones we suggest you read the descriptions for both zones and decide which best describes the climate where you live. Depending on the microclimate in your garden, you may be able to grow a wider range of plants over a longer season than others in your zone. Lucky you!
What is a microclimate? A microclimate is a small area where the temperature or humidity differs to the climate of the surrounding area. For example, if you live in a climate zone where frosts are common but your garden is protected by buildings or large trees, your garden may be frost-free. Similarly, if you live in a warm temperate zone but your garden is at a high altitude your microclimate may have more in common with the cool temperate zone, so use this as a guide when deciding which zone is relevant to you.
Can I grow varieties not listed for my climate zone? While our climate zones and sowing chart will help you decide what is suitable to plant in your garden, they provide general guidance only. We recommend you start by sowing seed that’s recommended for your climate zone; once you get a few successes under your belt you can experiment with varieties in neighbouring zones and see how you go – gardening is all about experimenting after all!
Purposefully ripping up healthy young plants may seem a strange and destructive thing to do, especially if theyve come from seeds youve sown yourself. But for many plant species its an essential part of successful cultivation. The process is known as thinning or thinning out, and heres why its so important.
Why Do Some Seedlings Need Thinning?
In the wild, plants have only one goal in life: to produce the seeds that will form the next generation. Any desirable side effects such as tasty fruits or spectacular floral displays are secondary to this purpose, and are largely the result of human-influenced selective breeding down the centuries.
The problem comes when a plant doesnt have the right conditions to grow at its own pace. When resources are short for whatever reason, the plant will push all its energies into forming those essential seeds, and the desirable side effects will be lost. The harvest will be poor or non-existent, the flowers will be fleeting and unimpressive, and so on. For example:
- Stressed radishes wont form the crispy, spicy roots most gardeners grow them for.
- Nutrient-starved lettuces will head straight to setting seed without providing lush leaves for the kitchen along the way.
- Ornamental plants may be tall and spindly rather than bushy and luxurious.
One of the main reasons for a lack of resources is when plants are grown too closely together. Overcrowding means theyre fighting for room in a small patch of soil, depriving each other of nutrients, water, and sunlight. Thinning out is the simple method of reducing the number of plants in any one space, so that each can take the resources it needs to grow healthily.
Thinning Seedlings! ✂️ // Garden Answer
FAQ
How do you thin seedlings?
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Wait for true leaves:Thinning is best done once the seedlings have developed their first set of “true leaves” (not the seed leaves).
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Check seed packets:Refer to your seed packet for recommended spacing, as different plants have different needs.
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Look for strong vs. weak seedlings:Once the seedlings have grown a few true leaves, you’ll be able to see which ones are the strongest and which are weaker.
What happens if you don’t thin out seedlings?
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Competition for Resources:When seedlings are too crowded, they struggle to access the resources they need to grow strong and healthy.
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Stunted Growth:Overcrowding can lead to stunted growth, where plants become tall and thin (leggy) instead of bushy and robust.
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Reduced Yield:Weakened plants may not produce as many fruits, vegetables, or flowers as they would if they had adequate space and resources.
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Increased Susceptibility to Pests and Diseases:Stressed plants are more vulnerable to pests and diseases, further impacting their health and productivity.
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Root Damage:If you wait too long to thin seedlings, their roots may become entangled, making it difficult to separate them without causing damage.
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Maximize Yield:Thinning allows you to select the healthiest seedlings and give them the space they need to thrive, ultimately leading to a better harvest.
How is thinning done?
In agricultural sciences, thinning is the removal of some plants, or parts of plants, to make room for the growth of others. Selective removal of parts of a plant such as branches, buds, or roots is typically known as pruning.
How long should seedlings stay in trays?
Typically, your seeds will stay in their seed tray for 4-6 weeks. After this period, you will either need to transplant the new seedlings into larger pots or transplant them outside. Check your seed instructions and pay attention to your frost dates before transplanting young plants outside.