Managing a wild flower roof in summer

Early to midsummer sees the UK’s wildflower green roofs at their very best.  Grasses swaying in the wind, flowers flowering and the wildlife benefitting to the max.  Just like a ground-level garden, maintenance at this time of year will make a big difference to the longevity and sustainability of your aerial wildflower display.

 summer wildflower green roof viewed from above

In this article we are looking at summer maintenance for the different life phrases of a wildflower roof.  Newly planted roofs and established roofs.

Summer maintenance for newly planted wildflower roofs

Whether it has been created using seed, plug plants of Meadowmat wild flower mats, a newly planted wildflower roof needs extra careful maintenance

Watering

The sole most important thing you can do for your green roof at this stage of its life, is manage soil moisture levels.   Until the plants are really well established and have strong root systems, be vigilant with your watering.   Never let the substrate (growing medium) dry out completely.

On a sloping roof, or one that is exposed to high winds, check on a weekly basis that the substrate is still damp.  Rainfall may not be enough to support these young, vulnerable plants.

On a flat roof, provided that the substrate is at least 100mm deep, keep an eye on the weather.  If you’ve had no rain for 2 weeks or more – it’s a good idea to switch on the irrigation and give the roof a good soaking.

At the first sign of plants wilting (looking floppy and sad) give them a really good watering.  Early morning or late evening are the best times of day to irrigate and don’t stop until the water is running off the roof.   Repeat daily until the plants recover.

Weeding

Meadowmat gives a good coverage of plants from day one with little opportunity for weeds to germinate between desirable plants.  You should have little cause to worry about weeding.

Plug plants or seeded areas however, tend to have largish areas of bare substrate between plants – at least in the first few months.   Find somebody who can tell the difference between a weed and the plants you have deliberately placed on the roof.  Then ask them to walk the roof once a month and pull out any unwanted species.  Put weeds straight into a sack and bring them down from the roof.  That way they cannot re-root into the substrate or drop seeds all over the roof.

Mowing

Mowing is an important part of wildflower maintenance and at ground level, wildflower meadows are mown between late June and Mid-August.

On a roof, mowing is best done in autumn time in order to make the most of the insulation properties of all that vegetation.   However, if your newish green roof has got too lush and the leaves are falling over and squishing lower plants – a quick haircut will remedy the situation.

Feeding

Never, ever add plant food to a wild flower green roof.  Wild flowers thrive in low nutrient conditions.  

If the plants are not thriving, check irrigation and drainage; look for pests and then ask yourself if these are the right plant species for the roof aspect.   Sun lovers won’t thrive in shade, tall plants can be buffeted by strong winds, salt laden coastal air doesn’t suit all species.

Summer maintenance for established wildflower roofs

Established wild flower roofs are unbelievable easy to care for.   Simply irrigate when necessary and be prepared to cut the vegetation back in autumn time.

Watering

For irrigation advice – look back to the “new roofs” section of this article.  Basically, if you’ve not had a decent rainfall for the last fortnight, give the roof a good soaking.

Weeding

Once the roof has stabilised and the plants are well established you’ll find that weeds are not too much of a problem.   If the roof has suffered a pest attack or struggled with weather conditions you may find some areas of bare substrate.  It’s possible that weeds will pop up here – if you don’t like the species pull them out.   Come autumn, you can re-seed or re-plant that patch with something you do like.

Mowing

Unless plants are falling over or grasses have dried out so much you feel they are a fire hazard – keep your scythe in your shed until September.  There’s no need to cut back vegetation at this stage.

wildflower green roof in late summer

This wild flower green roof is almost ready for its annual haircut.  As you can see, some of the plants have set seed and are beginning to fall overAnother 2 weeks and this will benefit from a trim and maybe some water to help it make new growth.

Feeding

Don’t do it!  The plants don’t want it, they don’t need it and you’ll upset the ecobalance on the roof.  Save yourself a job!

Help and advice

As always, if you’re in a quandary and need some advice on managing your wildflower roof in summer, talk to the team at Meadowmat.   Contact details are on our website or you can email Chris Carr with pictures of your roof and he will pass your query on to the best person to help you.

 

Case study:  A small wildflower green roof in London

Using Meadowmat to create a wildflower roof:  Written by Production Manager Robert Allen.  This is quite an old article, written before the development of Meadowmat for Roof and Garden.  However it does make some useful points about the weight of a wildflower roof and the importance of choosing the right plant species.

Meadowmat for Roof and Garden:  More about this pre-grown wildflower matting which has been developed especially for creating living green roofs with native plant species.

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