Grow your own kitchen sponges (loofahs)

Loofahs growing in the Kitchen Garden

From May to October head to the Kitchen Garden to see the crop of loofahs growing under shelter ready to be harvested at the start of November. First grown in 2019 this successful crop has helped reduce the use of plastic sponges across Knightshayes and are easy to grow at home as long as you have a greenhouse or poly-tunnel to ensure the fruits ripen fully.

What you’ll need:

Loofah Seeds - We have bought our seeds from lots of different nurseries including:

It's important to get the right variety and the seeds you need are called Luffa cylindrica. If you would like to use seeds from Knightshayes we will have a limited amount in May, just keep an eye out on Facebook for more information.

Compost – We recommend using a good peat-free organic compost like Fertile Fibre or Melcourt Sylvamix, but any good seed or multipurpose compost will do.

Pots - You’ll need some 9cm (or similar size) pots and larger ones for potting up later in the year. The final pot should be at least as large as a bucket.

Labels - We clean and re-use small white plant labels each year, but you can make them from cut up margarine tubs and yoghurt pots, or wooden lolly sticks.

Propagator - Loofah seeds need a pretty high 25 degrees Celsius for good germination so we recommend a small heated propagator box or a heated mat. It’s unlikely that you’ll get high enough temperatures on a windowsill or in an unheated greenhouse. If you don’t have a propagator box, you can maximise the temperature on a sunny windowsill in a nice warm room by making your own mini propagator using two (recycled of course) plastic fruit punnets, just tape them together and cover the holes up for extra warmth and to keep moisture in.

Watering can - You’ll need to keep the compost moist but not saturated. A fine rose on the end of the watering can is recommended to avoid overwatering.

Time to get started

Mid-April: Sowing time

Loofah seeds don’t germinate quite as easily as cucumbers or courgettes, so sow a few extra to be sure to have enough plants. Soaking the seed for a few hours in lukewarm water ahead of sowing can help to encourage better germination. Fill your pots up loosely with compost and tap down lightly once or twice. Hold the loofah seed, sides on, between finger and thumb and push it sideways down into the loose compost, about 1.5cm deep. Tap the pot again to settle the soil over the hole. Make sure you pop a label in to avoid mix-ups later. Then the pots need heat, lots of lovely heat! 25 degrees Celsius of heat. So, putting your pots into a heated propagator box is best for success. We have heated mats with adjustable thermostats in our nursery greenhouse, but you can try making your own propagator box and placing it on your warmest, sunniest windowsill if you don’t have a propagator. Once you’ve sown your seeds and placed them into the propagator be sure to water them water them. Avoid overwatering though, as this can cause the seeds to rot. Try to resist the temptation to keep taking the lid off for a peep, as this will let the built-up moisture out of the propagator. Germination won’t take long at 25 degrees, so check in a week but they may take 2 or even 3 weeks at cooler temperature. Too cool a temperature and the seed may rot rather than germinate, so the warmth is very important.

Mid May: Potting up

Once the roots are starting to show through the holes at the base of the pot it’s time to pot them up. We pot ours into bucket-size pots but if your indoor space is limited you could use smaller ones and increase the size as the plant grows.

Late May: Putting up supports

Now your loofahs are potted up you need to put in some supports for them to grow up. This could be a wigwam of bamboo canes, hazel sticks or even lengths of stout string or thin rope strung from the roof of the greenhouse and dropped down, to wind the plants onto as they grow. The vines grow vigorously so the supports need to be quite strong.

Late May – October: Maintance

The loofah needs a long growing season. To help with fruit ripening there are a few things you can do. Keep the compost moist but not saturated. We recommend a good deep soak to the root zone at the same time each day to keep the compost moist. Don’t overwater, loofahs don’t need as much water as courgettes or marrows. To discourage mildew on the leaves water your loofahs in the morning.  As the fruits begin to form keep an eye on how many there are on each plant, once 3 or 4 per plant have grown to 15-20cm long, remove any other young fruits that form. This will focus the plants energy into ripening those first fruits. Train in the new growth regularly so that you’re getting plenty of light and air to the fruits. Keep an eye out for pests and disease. Aphids can be squished by hand, blasted off with a hose or wait for ladybirds to arrive and eat them for you. If mildew is a problem, cut off and bin any affected leaves. Ventilate the greenhouse on hot days and warm nights, but as Summer goes on into Autumn, shut the greenhouse at night and on cooler days. Loofahs like it warm.

November: Harvesting and processing

In November, the fruits, which have felt spongy and squashy, should start to firm up as the fibres become stronger inside and the colour of the skin will begin to change from green to yellow. This is the time to harvest your loofahs.Cut off the fruit, then gently squeeze the skin all over, becoming firmer until you can feel it separating from the fibres inside. The skin needs to feel loose all over the whole fruit so that you don’t tear the fibres when you pull the skin off, so keep squeezing until you’re sure it’s separated from the fibres. Next, cut off the top and the bottom few centimetres of the loofah. Then get your finger or thumb under the skin and start to gently separate the skin from the fibres by sliding your finger between them. Once the skin is loose, it’s time to rinse out the seeds and any remaining flesh, to leave the fibrous skeleton behind. Put the loofah in a bowl of warm water. Squeeze all over, the loofah will become more flexible as it takes up the water and it will get easier to squeeze and pop the seeds out of one end. Once the loofah skeleton is well rinsed you can hang it up to dry, then cut to preferred size and use for you washing up. The loofah ‘sponges’ last for ages and can be popped into the washing machine or dishwasher as required.