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What is pinching out and why do we do it?
You may well have come across the concept of “pinching out” in reference to your tomato crop or your dahlias. It is a common practise among gardeners but using this technique effectively needs a little thought.
In the simplest terms, pinching out is a method of pruning young plants to encourage branching that will eventually bear more fruit or flowers, thereby increasing the yield. By literally pinching off the topmost part of the stem just above leaf nodes or buds, the plant will branch out to create new stems and branches.
There are a couple of other benefits to pinching as well. Firstly, pinching prevents your plants from getting too leggy. By encouraging growth in the branches lower down, you will eventually have a stronger central stem. Secondly, for those plants primarily grown for leaf (e.g. herbs), regular pinching will prevent plants going to seed too soon, so the foliage continues to be lustrous and full. Plants with decorative foliage, such as coleus, can be pinched to achieve the same result.
How to pinch out
Quick Tips for Pinching Out:
- Avoid damaging leaf nodes beneath the pinching point. Pinching with the fingertips is kindest, or finely pointed snips/secateurs.
- Don’t pinch out too soon. Wait until the plant has sufficient growth to withstand the pruning and has reached an appropriate height.
- Know when to stop. The more you pinch out, the longer you’ll be waiting for flowers/fruits. Pinching too much can also lead to very bushy plants that crowd blooms.
Because the young growth is so tender, it is easily removed by pinching between the fingers, but you can use snips if you prefer. Whatever method you use, try to avoid causing damage to the leaf nodes or the plant will struggle to grow new branches. You can repeat this process on the new branches too, if so desired, but don’t get stuck in a pattern that leads to over-pruning. Make sure you pinch close to the leaf nodes to avoid disease getting into the stem.
Stop pinching out once the plant is the desired shape and allow the plants to flower freely. While you are engaged in pinching out, the flowering will be delayed, but this is done in favour of a fuller plant that flowers and fruits for longer for the rest of the season.
Pinching out is best done on young plants, as pinching out on mature plants can be detrimental to their health. Deciding when to pinch out will vary with different plants, so if you’re not sure, it is best to check. Pruning too early can lead to stunted growth in some plants and removing too much foliage from a young plant may leave it destitute – the plant needs to be left with enough foliage to photosynthesise and develop.
Last year, I started pinching out my dahlias far too early and the plants did indeed get bushier, BUT the stems were stunted and the blooms so crowded together that many pests decided to take refuge. Some of the flowers never properly opened up and I spent a lot of time trying to fix my mistake. The moral of the story: don’t pinch too soon and know when to stop!
Pinching Tomatoes, Dahlias & Basil
Pinching is primarily employed for those varieties of plants that usually grow one main stem. Some gardeners’ favourites that are commonly pinched are cordon tomatoes, dahlias and basil. Scroll down for more examples of plants that benefit from pinching out. Here are some tips for the favourites:
Pinching Out Tomatoes
Indeterminate varieties of tomato respond very well to pinching. These are cordon or vine tomatoes, such as ‘Gardener’s Delight’, ‘Sungold’, ‘Beefsteak’ and ‘Sweet Million’.
Start pinching out your tomatoes once there are at least 6 sets of true leaves. You are aiming to cut back the side-shoots, rather than pinching from the top, because you want the main stem to keep striving upwards for a good while. (Put in canes for support to help them on their vertical journey.)
Sideshoots on tomatoes will be those coming at 45o between the main stem and branches. Pinching out sideshoots will force the plant to direct its energy into the main stems and fruits.
Once your cordon tomato plants have reached their maximum height, you can curtail growth in the main stem by pinching off the top below the uppermost blossoms. It is recommended to have a maximum of 7 trusses (stalks with lots of flowers which will turn into fruit ) on the plant to ensure the healthiest harvests.
It’s also important not to go pinching out on all your plants now that you know how. Only certain plants will benefit from pinching out, while others will find it actively detrimental. Determinate tomatoes (or bush tomatoes) will produce fewer fruits if pinched out, so do not pinch back your bush tomatoes!
Pinching out Dahlias
Wait until the main stem is around 12” tall with at least 4 sets of leaves before you commence pinching. Pinching out when the stem is still short will mean a squat and tightly bushy dahlia plant. When the flowers start to emerge, they will crowd each other and a lack of air circulation can result in pests and diseases. The beautiful blooms will also be harder to see.
The rest of the process is exactly the same: pinch out the uppermost tip of the stems just above a set of leaves. Once the flowers are blooming, cutting and deadheading also helps to stimulate strong growth and more flowers.
Pinching out Basil (and some general advice on trimming herbs)
Basil does particularly well from pinching back, as it tends to grow one central stem, but with a little encouragement, can grow bushy and leafy with plenty to use in your cooking.
When harvesting your basil, or any herb, always cut the stem down to just above leaf nodes as with the pinching method. Don’t be tempted to just pull leaves off. Bare stems will simply be a drag on the plant’s resources. Cutting the stem also promotes root growth too.
Herbs are a fantastic group of plants for novice gardeners to learn about pinching. Trimming herb plants regularly is the best way to encourage bushy growth and prevent legginess. Also, any trimmed branches become your harvest for cooking.
Which plants benefit from pinching out?
Flowers
- Dahlias – once the stem is about 1ft tall
- Petunias
- Sweet Peas – once you have 4 sets of leaves
- Fuchsias
- Pelargoniums/Geraniums
- Antirrhinums
- Marigolds
- Snapdragons
- Salvia
- Coleus
- Impatiens
Fruits & Vegetables
- Cordon or Vine Tomatoes (indeterminate varieties) – once you have at least 6 sets of leaves
- Chillies/Peppers – naturally grow 2 stems, but you can still practise pinching out. once the plant is 15-20cm tall. Pinch out tops to encourage better cropping. Pinching side shoots can help produce smaller chillies too.
Herbs
- Basil
- Tarragon
- Thyme
- Sage
- Oregano
- Mint
When Not to Pinch
Not all plants benefit from pinching back, and some can be fatally damaged when pinched to excess.
Plants that grow to be naturally bushy do not need to be pinched out. All you do is slow down the natural growth process and may result in a smaller yield. Determinate tomatoes such as tumbling tomatoes, are a good example of this.
Monocotyledons will not benefit from pinching out and it can actually halt growth or kill the plant entirely. This is because plants of this type store their energies differently and the act of pinching removes the growing tip. Some common monocots are grasses, alliums and most flowering bulbs like tulips, daffodils and lilies. Monocots will usually survive the process of pruning, and send up a fresh stem to replace the one that was cut. But one is all you will get; not bushy growth. In the case of chives, a monocot allium, we must cut the stem to harvest it and then wait for the stem to regrow. The plant continues to grow, but the only way to get a bigger yield, is to wait for the bulb to form offsets that become plants in their own right – or to plant more seeds of course.
NB: Pinching out can be used to intentionally stunt growth in some plants for controlled kinds of growth. For example, you can pinch young sunflowers to get shorter stems for cut flowers. But this is not recommended in most cases.
Some plants to avoid pinching:
Flowers
- Campanula
- Cockscomb
- Delphinium
- Sunflowers
- Larkspur
Fruit & Vegetables
- Bushel Tomatoes
Herbs
- Dill
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