On the website of Dialoog you can find plenty of tips to maintain your clothes as sustainably as possible. A few highlights:
Washing ecologically starts with your choice of clothing. Choose items that you can wash easily and that don’t need dry cleaning.
Choose the right products. Some guidelines:

• Detergents:
  • Go for plant-based laundry detergents. Some examples of eco-friendly detergents: Ecover, Sonett, Delhaize Milieuvriendelijk, EcoTip, Biotop and Eco-Lino.
  • If you’re a sucker for traditional products, use a concentrated detergent for colored fabrics and add non-chlorine bleach for white laundry (or buy an all-in-one concentrate for white laundry only).
• Fabric softeners:
  • Not using fabric softeners means going easy on the environment.
• Stain removers:
  • Ox-gall soap
  • Multi Magic by Ecover
  • Stain remover by Treffer
• Follow the instructions on the packaging of your laundry detergent: make sure not to over- or underdose!
• Limit the number of washes you do by only running full loads. Tip: fill the drum for economy, but make sure to leave a gap the size of a fist on top of the dry laundry.
• Lower your washing temperature. Washing at 30° suffices for most normal washes. I Prefer 30 has published a useful PDF that shows you what to wash at which temperature. The website states that 30° is enough for clothes that are only lightly soiled and that you should run a 60˚ wash every 5 cycles to avoid unpleasant smells. Washing at higher temperatures (60°) is only necessary:
  • when dealing with heavily soiled items
  • when dealing with clothes that came into contact with ill persons
  • when you are vulnerable for infections
  • to thoroughly clean kitchen/food preparation textiles
  • to thoroughly clean special items like healthcare uniforms, sportswear or cloth diapers
• Use different techniques or washinnovations

Want to 'buy Belgian', even when it comes to your washing products? Ever since 1980, Ecover has been investing in the development and the production of sustainable, effective laundry and cleaning products made from plant-based ingredients and minerals, nourishing people and the planet. Ecover wants to carry the green theme through to the entire organization and all of its activities. Ecover wants to help employees, clients and consumers get the most of their lives by offering products and services designed to be sustainable and produced in a sustainable way.

The Dutch company ‘Seepje’ sells laundry detergents that are 100% natural and has a an entire webpage with tips on how to wash sustainably. To add a couple of tips to the list above:

• Protect your clothes by washing them inside out. Close all zippers, hooks and buttons. Wash bathing suits and underwear in a separate laundry bag.
• Keep white laundry from turning grey by only washing all-white clothes together. Items that are part colored and part white need to go in with the colored laundry.
• Take care of your wool and silk pieces by using the special delicate wash program or by hand washing them at 20°. High heat and active spinning can cause wool to shrink or fray. Never twist or wring out woolen garments, but leave them to dry lying flat on a towel for instance.

Another Dutch initative is "Bundles". On the one hand, they want to stimulate sustainable laundry behavior, and, on the other hand, encourage manufacturers to go green. Their solution?

• Washing your clothes with someone else’s machine.
• Bundles comes to the rescue, installing a washer and/or dryer at your place.
• A washing-app provides tips and tricks to conserve energy and use less detergents.
• Bundles connects its machines to the internet to monitor each customer’s laundry behavior, so they can give personal advice on green laundry routines. (we all tend to wash at higher temperatures and use way too much detergent).
• Bundles’ washing machines are equipped with an automatic dosage dispenser and a load detector.
• The company offers subscriptions for the machines and their usage. Each month, you get the chance to unsubscribe.
• When the machine needs repairing, Bundles bears the costs.

To conclude, also try to iron less by putting freshly washed clothes on a hanger as quickly as possible (avoiding wrinkles). You can also hang wrinkled clothes in the bathroom when you take a shower. The steam will help lessen the wrinkle (a top tip for travelers!).