What is the correct pH for growing?

An image of a woman gardening with soil that needs pH testing
Published: 17 July 2022

pH measurement is an integral part of the gardening process to ensure the successful growth of flowers, vegetables, herbs and orchard plants. Regularly using a digital pH soil tester can help you stay within the correct range for higher yields and healthier plants. Read on to learn about the correct pH range for plants below:

How does pH affect plants?

pH is a scale of how acidic or alkaline a material, such as soil, is. 7 pH is neutral, while anything below is acidic and anything above is alkaline. The pH of the soil affects the ability for plants to grow successfully, with pH outside of the ideal ranges for plants potentially causing slow development, lower yield and in some cases, failure to grow. 

pH isn’t a static value, as this parameter can be affected by a wide range of different environmental and artificial changes, including:

  • Climate
  • Weather
  • Other plants
  • Irrigation
  • Soil type
  • Fertiliser
  • Nutrient availability

How do you measure pH for growing?

A digital pH tester or meter for soil is the ideal way to measure pH in your garden, vegetable patch or raised bed. By regularly measuring pH with a suitable soil pH tester, you can get insight into the current condition of the soil, allowing you to make any necessary changes to help your plants to thrive. 

Hanna’s tester range includes easy-to-use soil pH testers such as Halo2, which connects to an app on your smartphone to provide clear records of the pH level in soil over time. To learn more about how to test the pH of soil, see our complete guide here.

How can you change the pH of the soil?

Once you have a digital reading of the pH of your soil, you can choose to introduce different supplements and fertilisers to bring your growing area into the correct range. To reduce acidity, you can use lime and calcium carbonate. Ground-up eggshells are a common choice for gardeners. If the soil is too alkaline, irrigation is one of the most effective methods. Gypsum, iron sulphate, sulphuric acid, or calcium chloride can also be used.

Do all plants need the same pH range?

Plants have varying requirements for pH range, from vegetables like potatoes that thrive in more acidic conditions to sunflowers that prefer a pH closer to neutral. Understanding the preferred pH range for your specific plants can help you make the right choices with the supplements and fertilisers you use. See optimal ranges for some of the most common plants below.

Optimal pH levels of different plant types

Vegetables

Plants pH Range
Artichoke 6.5-7.5
Asparagus 6-8
Barley 6-7
Beans 6-7.5
Brussels Sprout 6-7.5
Corn (Maize) 6-7.5
Cucumber 5.5-7.5
Early carrot 5.5-7
Early potato 4.5-6
Egg plant 5.5-7
Late carrot 5.5-7
Late potato 4.5-6
Lettuce 6-7
Melon 5.5-6.5
Oat 6-7
Onion 6-7
Pea 6-7.5
Pepper 6-7
Pumpkin 5.5-7.5
Rice 5-6.5
Soybean 5.5-6.5
Spinach 6-7.5
Strawberry 5-7.5
String Beans 6-7.5
Sugar beet 6-7
Sunflower 6-7.5
Sweet potato 5.5-6.5
Tomato 5.5-6.5
Watermelon 5.5-6.5
Wheat 6-7

Flowers

Plants pH Range
Acacia 6-8
Acanthus 6-7
Amaranth 6-6.5
Bougainvillea 5.5-7.5
Dahlia 6-7.5
Erica 4.5-6
Euphorbia 6-7
Fuchsia 5.5-7.5
Gentian 5-7.5
Gladiolus 6-7
Hellebore 6-7.5
Hyacinth 6.5-7.5
Iris 5-6.5
Juniper 5-6.5
Ligustrum 5-7.5
Magnolia 5-6
Narcissus 6-8.5
Oleander 6-7.5
Paulownia 6-8
Primula 6-7.5
Rhododendron 4.5-6
Roses 5.5-7
Sedum 6-7.5
Sunflower 6-7
Tulip 6-7
Viola 5.5-6.5

Orchard Plants

Plant pH Range
Apple 5-6.5
Apricot 6-7
Cherry 6-7.5
Grapefruit 6-7.5
Grapevine 6-7
Lemon 6-7
Nectarine 6-7.5
Orange 5-7
Peach 6-7.5
Pear 6-7.5
Plum 6-7.5
Pomegranate 5.5-6.5
Walnut 6-8

Buy garden pH testers from Hanna

Hanna has a wide range of handheld electronic pH testers for gardens, from the Bluetooth-connected Halo2 to simple testers such as the HI-98118 Groline pH tester. Shop the full range of soil testers online today.

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