A guide to adopting a tree pit!

Our planet is experiencing a biodiversity emergency. Insects and birds are declining at alarming rates. We need to make our cities more nature-friendly. One small way we can do this is by watering the trees in our streets and planting wild flowers around their base. These will provide food and shelter for bees, butterflies and other insects. The more insects we can attract, the more birds they will support. Please consider adopting a tree pit in a street near your house.

There are 8,000 street trees in Portsmouth so this will make a difference. Watering a street-tree 2-3 times a week during dry weather will make it stronger and healthier. If you do plant the tree pit you will need to tie a sign around the trunk to let street operatives know that you have done so otherwise they may remove or spray the plants. Do share pictures of flowers growing in your tree pit via social media, and if possible share photos of a bee, butterfly, bird or other creature feeding or sheltering in or under the tree.

SAFETY

Wear protective gloves! You are gardening at your own risk. You may encounter discarded sharp items, rubbish, and other unpleasant materials.

SUITABILITY

If the street-trees nearest to your house are large with big roots and/or tarmac near the trunk you can still help the tree by watering the base 2-3 times a week during dry summer months.

TREE PIT PREPARATION

• Remove any rubbish and unwanted plants (“weeds”)
• Use small hand tools to gently loosen the soil, making sure you don’t disturb or damage the tree roots.
• If the level of the soil is below the pavement you can add new clean top soil.
• The final level of the tree pit should be same as the pavement. Raising soil levels can lead to stress to or death of trees and a drop in levels can create a trip hazard.

PLANT SELECTION

• Measure the soil depth of your tree pit.  If your soil is shallow (less than 20 cm) wild-flower seeds will work best.
• Where the soil depth is 20 cm or more wildflower seeds are still a great option because they will attract pollinators and other insects, but you should be able to plant small bulbs, annuals and perennials. Using seeds, plug plants or plants sold in small pots are best. Examples include small daffodils, narcissi, cyclamens, marigolds, geraniums, small periwinkle, salvia, thyme, grape hyacinths, alyssum, snap dragon, pansy.
• Avoid climbing plants and shrubs as they can create competition for water resources with existing trees.
• The best time to plant wildflower seeds is either September, or March/ April. The best time to plant bulbs is in the autumn. Most annual or perennial seedlings are best planted in late spring. Follow the planting instructions on the packet or label.

MAINTENANCE AND WATERING 

• Water both the plants and the tree during summer months – ask neighbours to help. Gently pour a washing up bowl or watering can full of water over the tree base 2-3 times a week whenever the weather is dry and warm.
• Cut back plants that encroach over the footpath
• Keep litter free
• Tie a sign around the tree trunk to inform street operatives that planting has been undertaken. We can provide you with one, if you don’t want to create your own.